Published by Megger
October 2010
The industry’s recognised information tool
ELECTRICAL
TESTER
The SMRT way to test relays
protective relay test sets also need
generous short time ratings. The benchmark of performance for an amplifier with
a 30 A continuous rating is a short-time
rating of 60 A, plus the ability to supply up
to 180 A at high power for instantaneous
overcurrent test applications.
So much for the brawn, but what about
the brain? After all, as every protection
engineer knows, power is nothing without
control. Let’s start with the user interface, as
this is what makes the difference between
a test set that’s a pleasure to use, and one
that’s viewed with dread and foreboding.
The gold standard in this area is set by
the latest touch-screen interfaces that
provide a simple way of testing even the
most complex relays. They allow users to
perform manual, steady-state and dynamic
tests quickly and easily, and they have
built-in preset test routines for popular
relays. Naturally, the new generation test
sets also make provision for automatic
testing, using powerful yet intuitive
software running on a PC.
It’s clear that the new generation relay test
sets will handle all of today’s demands
with ease and convenience, but what of
the future? Relay test sets are no trivial
investment, and users rightly expect them
to retain their value and usefulness for
many years.
The secret of testing the SMART GRID revealed!
Stan Thompson
Product Manager
With the challenges of testing the smart
grid just around the corner, and IEC
61850 networking starting to transform
the way substations operate, is now really
a good time to be thinking about buying
a protective relay test set? Surprisingly
perhaps, the answer is yes – provided that
it’s a smart test set that has been designed
with future developments in mind.
The reasons for investing now rather than
waiting are simple: there’s a new generation
of test sets that makes testing easier, faster
and more convenient. And, in today’s highpressure world where time – and downtime
– are everything, which protection engineer
doesn’t need these benefits now rather than
later?
Let’s take a look at what makes these
revolutionary new test sets so attractive.
First of all, they’re light and small. To put
this in perspective, it’s not so very long
Moisture in current transformers
Exploding CTs are a real issue in Europe and
North America. Failure of a substation-type oilimmersed CT can lead to a high-energy release
and thermal runaway, very possibly resulting in
an explosion. At a number of recent failures, the
cause has been linked back to moisture ingress.
In the first of a two part series, we examine how
to identify these possible catastrophes before
they happen with a combination of simple
procedures and a clever test tool. See how it’s
done on page 4.
www.megger.com
ago that a complete three-phase test set
with modest output power weighed in
at around 150 kg, and even today, most
of the instruments on sale tip the scale at
around 25 kg. The new test sets halve this to
12 kg and they are also smaller than their
predecessors, making them much easier
and more convenient to transport and
handle.
Size isn’t everything, however, although it’s
undeniably important! Protection engineers
also need versatility. For testing threephase schemes, three current outputs plus
three voltage outputs are the minimum
requirement, but if numerical current
differential relays are to be tested, six
current channels are needed. The most
convenient and economical way to provide
these is to arrange for the three “voltage”
channels to be convertible, so that they can
be used either for current or voltage, as
required.
With their requirements for size and
versatility addressed, protection engineers
will undoubtedly turn their thoughts to
power. For convenient testing, current
Erratic readings!
Now to avoid errors when tesing in electrically
noisy environments, see page 2.
amplifiers with a constant power output
are highly desirable, and it needs to
be a high constant power to allow the
testing of protection schemes that use
electromechanical relays – we may be
looking to the future, but legacy equipment
is still going to be with us for a very long
time.
Fortunately, despite their small size and
weight, the new generation test sets have
no problems in the power department.
They can offer a full 200 VA up to 30 A,
with a compliance voltage of 50 V at up to
4 A. They even make provision for current
outputs to be series connected to double
the compliance voltage to 100 V and
provide a constant 400 VA output power.
Of course, power is also important for
the voltage outputs and the designers of
the new generation test sets have taken
this into account. From 30 V to 150 V, the
voltage amplifiers can deliver a constant
150 VA, thereby providing high current at
“difficult” low test voltages.
The best of the new test sets fully address
this requirement. Their logic systems
feature high-power processors to take
care of future requirements, and their
functionality can be readily enhanced to
meet changing requirements by means of
firmware upgrades.
But what of IEC 61850? As might be
expected, new generation test sets are
IEC 61850 ready. That is, they can be
supplied now without integrated IEC
61850 functionality, to eliminate the need
for users to pay for features they don’t
currently require, but they can be upgraded
easily and economically to provide full IEC
61850 support as soon as the user has a
need for it.
Hopefully, by now these new protection
relay test sets are starting to sound like a
very attractive investment, but how can
you get hold of one? The answer is simple
– contact Megger. All of the characteristics
and benefits discussed in this article are
embodied in the new SMRT 36 test sets
and, if you would like one, they’re ready
for delivery right now!
Continuous power rating is one thing, but
Safety first
Calling planet earth
There have been too many avoidable accidents
caused by ignorance of basic safety procedures.
It may seem obvious to seasoned electrical
engineering professionals, but insulation testers
can store a lethal static charge in its capacitance
and polarisation of the molecules in the insulation
material. If the instrument is discharged, the
user will not want to be part of the discharge
circuit. If you want to be safe around your test
instrumentation, then reading our article on
page 6 could be a life-saver.
‘So just how do you get your clamp-on earth
tester down a pit when the jaws are the wrong
shape? And what happens when the serrated
jaws get dirty or misaligned? It must seem sometimes like your test tools conspire against you to
make life difficult. The obvious solutions – are
an oval jaw that has the capacity for a normal
cable, and the ability to reach into awkward
places; and flat jaws with some behind-thescenes- complex circuitry to eliminate alignment
issues. Read more on page 3.
Megger ELECTRICAL TESTER October 2010 1
Contents
The SMRT way to test relays.............. 1
Stan Thompson, Product Manager
Keep the noise down!
Paul Swinerd
Product Manager
Electrical noise is the enemy of accurate measurement, and it is often a particularly acute
problem in high-voltage insulation testing. But what exactly is electrical noise, what are
its effects and what can be done about it? Paul Swinerd supplies the answers.
Keep the noise down!......................... 2
Paul Swinerd, Product Manager
What is electrical noise?
The term electrical noise is used to describe a
whole range of phenomena, but the most general
definition is spurious electrical or electromagnetic
energy that produces an unwanted effect. In a hi-fi
system, the unwanted effect might, for example, be
background hiss, but in measurement systems
it most usually manifests itself as inaccurate or
unstable readings.
Ground test auto................................. 3
Paul Swinerd, Product Manager
The next step in insulation
diagnostics.......................................... 3
Matz Ohlen, Director - Transformer Test Systems
Moisture contect detection................. 4
Diego Robalino, PhD, Applications Engineer
Norwegian Blues................................ 5
Per Vågsether, Applications Engineer
In measurement applications, noise takes the form of voltages and currents induced from adjacent
equipment. This is very common in substations,
and particularly in high voltage substations where
induced noise at power frequencies predominates.
Ask Jowett - Warning - Safety first...... 6
Jeff Jowett, Applications Engineer
The EGIL has landed.......................... 6
Romain Douib, Product Marketing Manager
Magnetic losses, finances and
environment....................................... 7
Dr Stan Zurek, Magnetics Technical Specialist
Q&A.................................................... 8
The story of Multi-Amp...................... 8
Bruce Buxkemper, VP, Megger Dallas
Megger makes beautiful music........... 8
What is the effect of noise?
In insulation testing, electrical noise superimposes an AC signal on the DC test current. This
can cause readings to vary erratically, and can even prevent a reading of any kind being
obtained if the level of noise exceeds the capabilities of the instrument. Many operators
see this as something they have to live with – a form of occupational hazard – but, as we
shall see, this doesn’t have to be the case.
These instruments have a noise immunity
of 4 mA at power frequency, and have
been successfully used in some of the
world’s noisiest switchyards. Nevertheless,
the question remains – can noise levels
exceed 4 mA and if they do, what can be
done about it?
The answer is that noise levels of more
than 4 mA are very rare, but they are not
unknown. They may be encountered for
example, where making connections to
the bushings on the top of a transformer
involves the use of very long test leads,
since these act as effective aerials for
picking up noise. In these circumstances,
the best course of action is to take steps to
minimise noise pick up in the first place.
How can the effects of noise be
reduced?
One of the most effective ways of minimising noise pick up is to take care with
the test lead layout. In particular, keep the
leads as short as possible and route them
near to grounded objects, such as the
casing of a transformer.
One solution of course, is to implement a complete shutdown of adjacent plant to eliminate
the noise source, but this is in many cases both costly and inconvenient. More often, noise
leads to tests being omitted, which is very undesirable since the objective of diagnostic
insulation testing is to prevent expensive and dangerous failures.
How can insulation testers deal with noise?
Noise immunity can be designed into insulation testers and indeed, instruments that are
sold in the EU must meet the EMC requirements of the latest edition of IEC 61326-1,
which came into force in February 2009. Megger has its own EMC laboratory at its Dover
site, which it has used to ensure that all of its latest MIT and S1 5 kV and 10 kV not only
meet this standard, but also conform to the requirements for heavy industrial use.
However, even that is not always enough. Experience has shown that in extreme environments
such as HV substations, instruments can be subjected to levels of noise far in excess of
those laid down in IEC 61326. That’s why it’s essential not only to look for standards
compliance, but also to take into account the noise immunity specification of an instrument.
What do noise immunity specifications mean?
It’s very easy for an instrument manufacturer to say that its HV insulation testers have high
noise immunity, but unless the level of immunity is specified, such claims are worthless.
But exactly how is noise immunity specified?
A typical specification might say that the instrument has an immunity of 2 mA at 50/60 Hz.
This means that if the noise current induced in the test circuit at power frequency is 2 mA
or less, the instrument will give accurate and reliable results.
Adjacent live cables
inducing noise current
A printed newsletter is not as interactive as its
email equivalent so to help you find items quickly
on www.megger.com, we have underlined key
search words in blue.
Adjacent equipment
radiating noise
Test piece
<2 mA Max.
Note from the Editor
Time for your say.
We have introduced a ‘Questions and Answers’
section and would like your input. If you have any
questions or stories that you think we could use,
then please email electricaltester@megger.com
The word ‘Megger’ is a registered trademark
Megger Limited
Archcliffe Road Dover Kent CT17 9EN
T +44 (0)1304 502100
E electricaltester@megger.com
www.megger.com
2
When screened test leads are used, the
screen is connected to the guard terminal
on the insulation tester. This ensures that
noise currents are diverted away from
the measuring circuits and are, therefore,
ignored. The guard terminal is also used in
the normal way to eliminate the effects of
leakage currents.
It is important to note that shielding is only
effective in reducing noise pick up on the
test leads. If noise is picked up on the test
piece itself, as might well be the case with
long overhead power cables, for example,
there is no substitute for using an instrument
with high noise immunity.
‘Views expressed in Electrical Tester are not necessarily
the views of Megger.’
Editor Nick Hilditch.
T +44 (0)1304 502232
E nick.hilditch@megger.com
www.megger.com
Another effective option is to use screened
test leads. The short test lead between the
insulation tester and ground will not pick
up enough noise to cause problems, but it
is often beneficial to use a screened lead
for the longer connection to the equipment
under test. Megger offers suitable leads in
lengths of 3 m, 10 m and 15 m.
Specifying the maximum permissible noise current at power frequency is actually considering
the worst case, as instruments usually incorporate capacitive filtering that increases in
effectiveness as frequency rises. As a result, the noise immunity of the instrument also
increases with frequency. This can be very useful, for example, with corona discharge on
bushings, which typically generates electrical noise with frequencies in the kilohertz range.
While noise immunity of 2 mA is adequate for the majority of applications, there are
extreme environments such as substations operating at 300 kV and above, where even this
isn’t enough. For applications of this type, Megger has produced HV insulation testers that
not only incorporate specially developed input filtration to minimise the effects of high
frequency noise, but also employ firmware filtering to remove low frequency effects.
Megger ELECTRICAL TESTER October 2010
Electrical noise is undoubtedly a troublesome issue in HV insulation testing,
especially in substation environments.
By choosing instruments with high noise
immunity however, and using shielded
test leads where appropriate, it should be
possible to make accurate and dependable
measurements in even the most challenging
of circumstances.
www.megger.com
Ground test auto
Paul Swinerd
Product Manager
For many years, stakeless or clamp-on testing has been
accepted as an established method of testing earth system
resistance, and is now included in the German standard
VDE 0100-600:2008 (appendix B3). This method has a number
of real user benefits, in particular not having to disconnect the
electrode under test, increased user safety and huge savings in
time and aggravation.
However, many users are failing to enjoy the benefits of stakeless testing, and that’s mainly down to two main issues. Firstly
many potential users do not fully understand the testing
technique, and avoid it; secondly many people have found
some problems when testing, resulting in a number of
concerns.
The first issue is easy to solve when you know where to go.
You can find forums and micro-sites such as the one at
www.megger.com/det to help with many of these problems,
or you could phone one of Megger’s regional technical
support offices. Easy, if you have time to stop your work and
do the research!
The second issue is not so easily fixed. Problems experienced
in actual testing are often caused by the abilities – or inadequacies
- of the test equipment. Let’s take a look at these concerns and
see how we can eliminate or maybe get round them.
For obvious reasons, most users have safety as their primary
concern. In substation environments, the stakeless testing
method may be the only method available to you. But what
happens if you are holding the instrument when a massive
fault produces a huge transient on the cable that you happen
to be clamped around? This could also be a concern to users
testing lightning protection; there can be a sudden lightning
bolt that could kill you. The other and maybe less obvious
hazard will present itself if, for whatever reason, the user has
to disconnect one of the electrodes that is being tested. If
there is too much current flowing down the electrode when it
is disconnected, it will quickly turn into a hazardous voltage.
What’s the answer? Firstly, choose an instrument with the
highest IEC safety category; it will have the best isolation
between your hand and what ever you are clamped around.
Secondly choose one that has a current measuring range, then
you can measure whether there is a hazardous level of current
flowing before you disconnect.
If you work in a sub-station environment you may also have
another concern which many users have no doubt experienced. Noise interference in the form of leakage currents
flowing through the electrode under test can result in varying
readings or in some cases actually prevent testing completely.
In this case the solution is to select an instrument with the
highest noise current immunity you can find.
Many electrodes are in difficult to access locations; in boxes,
pits or are just difficult to reach. What can you do in these
situations? Your choice of instrument will directly influence
your success in such situations. Choosing a clamp with a large
jaw capacity is not just about the size of cable it can clamp
around, it will also provide a better angle of approach. Also,
look at the instrument’s body length. The longer it is, the
more instrument there is to accommodate down
an electrode pit. Another feature that will help
with access is to have a jaw head that is slimmer in
profile, and a backlit display will surely help too,
especially in substation basements.
Lets recap and talk about clamp capacity. The
challenge isn’t always to clamp around the large
size of cables, as there may also be a requirement
to clamp around flat earth tapes. In many cases
these flat tapes have to be pried from walls, so a
smaller section clamp will help. However these
tapes are getting bigger, and in some locations
such as on earth systems used on ~400 kV supplies
they can be 50 mm x 10 mm. That really limits
your choice of how to test.
The other burning issue is reliability. Earth testing
clamps get used in tough environments and are
often used in remote locations such as on utility
pole electrodes. Many instruments have interlocking
laminations (or interlocking teeth as they are often
referred to). These ‘teeth’ are easily damaged and
collect dirt which can either produce errors in
measurement, or render the instrument useless and
awaiting a trip to the repair shop. The answer is to
use an instrument with smooth mating jaw surfaces.
That sounds obvious but it is often overlooked.
Also carefully check the instrument’s battery life
and check that there are readily available batteries
in the location where you will be working. In a
remote area, this could be a real concern to the
user.
Stakeless testing has real advantages and specifying
the right instrument will really help get the best
out of the method.
Megger has just launched a new range stakeless
testers specifically designed to overcome the problems
outlined in this article. The new DET14C and
DET24C have these new features:
n
n
n
n
n
n
n
CATIV 600 V safety, with 8 kV of transient isolation
Auto hazardous current warning even on the resistance range, giving you peace of mind, and no need to worry about remembering to measure it
Auto noise filter to provide the best of immunity to noise current
Unique elliptical shape head with a 37 mm x 55 mm capacity and slim profile which
provides excellent access and can clamp around a 50 mm x 10 mm earth tape
Smooth mating jaw surfaces which are easy to clean and have no teeth to bend
Huge battery life from readily available AA batteries, which last 24 hours with a 25 Ω load
Pre-hold function which automatically initiates a test when clamped around an electrode, then The next step
in insulation
diagnostics
Matz Ohlen
A new generation of instruments is now
available which addresses these shortcomings.
To see what these versatile products have
to offer, let’s take a look at one of the latest
12 kV insulation diagnostic systems.
The first thing users are likely to notice is
that it is much more portable than its older
www.megger.com
holds the reading for reviewing when removed from the electrode.
n Backlit display
With all these ground test auto functions, you could find your
worst problems just go away!
The ability of the test set to generate its
own test voltage, which can be varied
in frequency over the range 1 to 500 Hz
not only increases its versatility, but
also ensures that dependable
and repeatable results are
obtained even when
the instrument is fed
from a poor quality
supply.
Director - Transformer Test Systems
High-voltage insulation testing is an essential
tool for condition assessment of almost all
major items of electrical power plant,
including transformers, bushings, circuit
breakers, cables and rotating machines.
Many of the insulation test sets currently
in use, however, have significant shortcomings,
which means not only that they are less
convenient to use than they should be,
but also that the results obtained are less
comprehensive and less reliable.
counterparts
– its two-piece
design weighs a
total of 36 kg,
making it probably the
industry’s lightest
power factor test set.
Another useful benefit
is provision for fully automatic tan delta/
power factor and tip-up testing, which is a
big time saver. Facilities are also available
for manual testing – including the option to
increase the test voltage during the test – to
allow special testing requirements to be
accommodated.
Another benefit
is automatic voltage
dependence detection.
If the instrument
detects, for example,
that the dissipation
factor of the test object
varies with the applied
voltage, which suggests
there is a problem that
requires further investigation,
it instantly provides a user alarm.
The inability to correct accurately for
temperature differences when calculating
results is a weakness of many insulation
test sets currently in use. The new generation
instrument overcomes this by using a
novel method to apply individual and
accurate temperature compensation for the
actual test object. This is based on
carrying out an additional DFR measurement
and mathematically converting data at
different frequencies to data at different
temperatures.
Results analysis is a key aspect of insulation
testing and, in the new instrument, analysis
is facilitated by allowing immediate
comparisons to be made between the
current results and stored data sets.
Comparisons of results of obtained at
different voltages and frequencies can also
easily be made.
The instrument is supplied complete with
powerful industry-standard acceptance
and maintenance test data software, which
not only offers extended test automation
options, but also provides comprehensive
facilities for archiving, analysing and
reporting results.
The instrument described in this short item
is Megger’s recently launched DELTA4000
series 12 kV insulation diagnosis system,
which is supplied with the powerful yet
easy to use PowerDB software package.
Developed after careful analysis of user
requirements in relation to high voltage
insulation testing, this innovative new test
set is a significant step forward in highvoltage insulation testing technology.
Megger ELECTRICAL TESTER October 2010 3
MOISTURE CONTENT
DETECTION IN OIL
IMMERSED CURRENT
TRANSFORMERS
Diego Robalino, PhD
Applications Engineer
Part I. Measurement Set Up
As discussed in the last issue of Electrical Tester, frequency domain spectroscopy (FDS)
is an invaluable tool for determining the moisture content of the solid insulation in
combined oil-paper insulation systems. In particular, work carried out in North America
and Europe has verified the effectiveness of FDS as way of determining the moisture
content in instrument transformers and, more specifically, in high voltage current
transformers (CTs). This article describes FDS testing of CTs. It includes configuration data
and a step-by-step test procedure using the Megger IDAX 300 test set. Part 2, which will
appear in the January 2011 edition of Electrical Tester, discusses analysis of results using
MODS software and gives recommended values for new and aged units.
The dynamic properties of dielectric materials can be measured in the time and/or
frequency domain. The fundamentals of dielectric response functions and the theory of
dynamic properties of dielectrics are well described in several publications and, in
particular, in a very detailed way in two articles by W S Zeangl, which appeared in the
IEEE Electrical Insulation Magazine Vol. 19, 2003.
The traditional dissipation factor testing technique allows identification of the deterioration
process of the insulation by measuring the changes in the dielectric properties of the tested unit. This approach involves measurements of capacitance and dielectric loss quantified
by the loss or dissipation factor . This type of testing is part of many manufacturing quality
control procedures but it is normally carried out at power frequency only. With FDS,
however, a wide frequency range from 0.001 to 1000 Hz is used, and this allows the
determination of the moisture content in the solid insulation.
Water significantly accelerates the ageing of cellulose. Oil analyses by means of Karl
Fischer titration (KFT) have traditionally been used for the evaluation of moisture content,
assuming existence of equilibrium in distribution of moisture between oil and paper/
pressboard. In reality, the analysis only reflects the moisture percentage in the liquid
insulation and equilibrium curves are required to estimate water content in the cellulose
insulation. The equilibrium curves are a useful reference but their reliability is still a topic
of discussion. Moreover, continual sampling for DGA and water content analysis is not
recommended for CTs due to the small volume of dielectric oil they contain.
“A chain is no stronger than its weakest link”………. [1868 L. Stephen in Cornhill Mag.
XVII. 295]
Failure of a substation-type oil-immersed CT can lead to a high-energy release and thermal
runaway, very possibly ending in an explosion (see Figure 1). Because of the difference in
thermal expansion ratio between the metallic housing of the CT and the relatively fragile
porcelain insulator, mechanical stress builds up, resulting in a blast where fragments from
the porcelain insulator may reach up to 50 m from the location of the unit. Loss of this
important device results in phase to ground fault that will trip the substation, shut down
operation and possibly affect other electrical components in the vicinity.
Figure 2 - Cross Section: CT windings, core & insulation
In some applications, the core housing can accommodate up to six independent multiratio
cores feeding protection relays, or cores feeding a combination of relays and meters,
requiring up to 30 secondary leads. More details of the construction of oil-immersed CTs
can be found on manufacturers’ web sites and literature.
A very real concern
The issue of exploding CTs is currently a very real concern as, in Europe and North
America, there have recently been several catastrophic failures of hermetically sealed units
in sub-station applications. Initial investigations carried out on CTs similar to those that
have failed, using dissolved gas analysis (DGA), have revealed that the failures are due to
moisture ingress, and that many CTs still in service are at risk of similar failures. Regular
CT testing is, therefore, increasingly seen as essential but, as has already been noted, tests
that involve oil sampling, which includes DGA testing, cannot be used regularly on CTs
because of the small volume of oil they contain. FDS testing, which eliminates entirely the
need for oil sampling, is therefore establishing itself as the preferred approach.
Performing FDS tests on an oil-immersed current transformers
First make a visual inspection of the unit and its surroundings. Ensure that local safety
procedures (tag-out/lock-out) have been observed and that the test area is properly
identified and is free of obstacles on emergency evacuation paths.
The procedure for testing a HV CT uses the same configuration as that used to perform
power factor/dissipation factor tests. Thus, the unit must be isolated from the power
system (primary as well as secondary winding) and discharged. If the test is to be
performed after a through fault, it must also be demagnetized. As a general rule, when a
series of tests is to be carried out on an HV CT, DC tests should be performed last.
With a clear area of operation established, confirm that good connections have been
made to the unit under test (UUT), to the substation’s ground system, and from the test
instrument to the same grounding point. Typically, the ground terminal of the test
equipment is connected to the same ground terminal on the secondary box of the CT.
The CT is tested using the standard method. This implies energizing the primary winding and measuring the secondary connected to ground. The recommended test setup is
grounded specimen test (GST) as shown in Figure 3.
Core
Liquid
insulation
Solid
insulation
Low voltage
winding
High voltage
conductor
Figure 3 - GST measuring setup for HV CT
Figure 1 - Failure of a CT in a substation
The internal construction of typical oil-immersed CT is shown in Figure 2. The high
voltage/high current primary winding is a conductor, a bar or a set of conductors passing
through the window of the toroidal core. Engineers or technicians testing the unit should
verify with the manufacturer the construction of the primary conductor, as there are
applications where a single conductor is wound inside the CT to provide multiple turns.
The core is surrounded by the low voltage winding, which is evenly distributed all along
the toroidal core. This is completely covered by solid insulation, which wraps the secondary winding and the core in multiple layers of paper insulation. The core, the primary and
secondary windings and the solid insulation are fully immersed in liquid insulation
(mineral dielectric oil).
4
Megger ELECTRICAL TESTER October 2010
Normally, there is no need to short circuit the primary winding but if, as mentioned earlier, there are several units built in with multiple turn arrangement of primary conductors,
these need to be shorted. Bar-type and single-conductor primary windings do not require
short-circuiting of the P1-P2 terminals.
The UUT should preferably be at thermal equilibrium. The average temperature of the
insulation should be measured or estimated and recorded. One option is to measure on
several positions on the outside of the CT core housing with a pistol grip laser target
temperature gauge or, if the CT has not been in recent operation, the insulation
temperature can be assumed to be the same as ambient temperature.
www.megger.com
Per Vågsether
Sales Engineer, Tormatic AS
Norwegian Blues
Per Vågsether, Sales Engineer at Tormatic AS, a leading supplier of equipment and consultancy
services to Norway’s power industry, provides an overview of the Norwegian energy supply
sector, and explains how global warming is creating problems that are giving electrical utilities
a definite attack of the blues.
Hydro electric power
As might be expected in such a mountainous country, most of Norway’s electricity is generated
by hydroelectric plant. In fact, Statkraft, a power utility which is wholly owned by the
Norwegian government and which supplies much of the country’s power, is Europe’s largest
renewable energy company.
In recent times Statkraft has diversified its operations, partly for reasons that will become clear
later in this article, and now, in addition to hydroelectric power, it is also involved with wind
power, gas power, solar power and biopower.
In 2008, the latest year for which figures are
currently available, Norway had a total of 737
power stations, of which 691 were hydroelectric, 29 thermal and 17 wind power. The
total installed generating capacity was almost
31 GW. During the year, Norway produced
142 TWh of electricity, almost all of which
was consumed domestically, one of the
largest users being the aluminium industry
that developed in the country principally
because of the availability of cheap electricity.
Norway power stations in 2008
Norway has an open electricity market and it routinely imports and exports energy over direct
power links with countries that include Sweden, Denmark, Germany and the Netherlands.
Since Norway, with its large hydroelectric power base can, for most of the time, generate
electricity at lower cost than its neighbours, energy exports predominate over imports. In 2008,
for example, it exported 17.3 TWh and imported only 3.4 TWh.
Deregulation
Norway’s power distribution companies were deregulated and privatised a few years ago.
Consumers are, however, still tied to their local distribution companies in an arrangement
the Norwegian Ministry of Petroleum and Energy describes as “monopoly regulation”, which
includes an income cap for each network company.
Monopoly regulation is intended to safeguard consumer rights while ensuring a wellfunctioning power market and that the grid is developed and managed efficiently. The
regulatory system has recently been fine-tuned to provide enhanced incentives for investment
and to make it more certain that the benefits of efficiency improvements will be passed to the
customer.
In spite of this arrangement, the privatisation of the power companies and the recent acquisition
of some of them by foreign organisations have brought mixed benefits. These developments
are certainly working well for the owners of the companies, but not necessarily quite as well
for energy users, who are seeing higher prices with no perceptible improvement in performance.
These criticisms may, however, be a little unfair as Norway’s energy prices are still among the
lowest in Europe, and the country’s transmission network already has one of Europe’s highest
uptimes.
The effect of global warming
There is, however, a much bigger cloud on the horizon, one that is certainly significant enough
to create a distinct feeling of “the blues” among energy producers and consumers alike. This
problem is that the amount of energy available from hydro-electric power plants, on which
the country is highly dependent, is falling. And it is by no means certain when, or even if this
decline will end.
It’s not hard to find the reasons for this. Hydroelectric generation depends on water flow and,
in Norway’s case, most of the water comes from melting snow. Because of global warming,
however, much less snow is now falling, so there is much less melt water, which means
significantly reduced generating capacity. With these facts in mind, it’s not hard to see why
ecology and environmental protection are currently such hot topics in Norway.
Of course, the utility companies are responding to this issue, typically by putting research
efforts into alternative green energy sources, such as wind power and wavepower, the latter
being a particularly attractive option given the country’s very long coastline.
There’s a very long way to go before these sources make a significant contribution, but it
is worth noting that Norway was the first country to generate electricity commercially with
seabed tidal power, when a prototype 300 kW plant was brought into service near Hammerfest
late in 2003.
Wind power
The utilisation of wind power in the country is considerably more advanced, with some 913
GWh of electricity obtained from this source in 2008. Nevertheless, there are concerns about
building more on-shore wind farms, not least because, in spite of their excellent carbon footprint, they are thought to adversely affect the environment in other ways, such as disrupting
the breeding of eagles. Offshore wind farms are seen as a more attractive proposition, in spite
of the higher costs and the technical difficulties involved.
Another option under consideration is the building of new gas-fired thermal stations, which
initially seems logical as Norway has access to large reserves of natural gas in the North Sea.
There are very great environmental concerns with this course of action, however, because of
the CO2 emissions that are almost unavoidably associated with hydrocarbon fuels like natural
gas.
For this reason, there are many who suggest that the natural gas should be seen as an export
opportunity and sold to other countries like the UK, where gas-fired power stations are already
www.megger.com
Norway has an ambitious plan to cut greenhouse gases
in widespread use. Unfortunately, this does seem rather like transferring the problem to a
neighbour, rather than genuinely solving it.
Ambitious plan to cut greenhouse gases
However challenging they may be, these issues will have to be addressed promptly as, in
January 2008, the Norwegian government set itself what it describes as “the world’s most
ambitious target for cutting greenhouse gas emissions” – this is to make the country as a whole
carbon neutral by 2030.
The full details of how this is going to be achieved remain a little sketchy, but the plan is not
only to reduce CO2 emissions at home, but also to invest up to 3 billion Norwegian Kroner
(about US$ 0.5 billion) per year to combat deforestation in developing countries and thereby
gain carbon credits.
For decades, Norway has enjoyed cheap “green” electric power, and the country is still well
blessed with renewable and non-renewable energy resources. Nevertheless, as we’ve seen,
there are major issues to be addressed over the next few years and as a result, this will undoubtedly be a very interesting and challenging period for all of those involved in the
country’s energy sector.
Megger ELECTRICAL TESTER October 2010 5
Warning!
Safety first
Jeff Jowett
Applications Engineer
Safety should be the first concern
when preparing to carry out
electrical testing, but all too often
it’s taken for granted. Lack of
attention to safety requirements
and lack of sufficient expertise can,
however, have life threatening
consequences. This two-part
article, the second part of which
will appear in the next issue of
Electrical Tester, explains how
safety requirements should be
systematically and thoroughly
assessed before testing commences.
The first essential for safe testing is to keep
in mind that safety involves equipment,
procedure, and the test item. Each should
be considered in turn. Beware of focusing
entirely on one aspect and letting the
others take care of themselves. Equipment,
for instance, may have adequate or even
superior safeguards while the item being
tested presents an overlooked danger. Of
paramount importance is the degree of
protection against arc flash/arc blast. This
combines elements of all three: the test
instrument, the test item, and procedure.
Arc flash protection is covered by the
standard EN61010-1:2001, issued under
the aegis of the International Electrotechnical
Commission (IEC). The rating defines
the level of spike or surge transient the
instrument has been designed to withstand. Remember, the rating pertains to
transient voltage, not line voltage. Spikes
can be many multiples of line voltage and
can cause test instruments that happen to
be connected at the time to arc internally.
The arc can produce tremendous heat,
violent expansion of air in a small space,
exploding the instrument and exposing the
operator to burns, shock waves and flying
particles. The key to safety is to design the
instrument so as to minimize the risk of
internal arcing, but that isn’t enough. The
operator must understand the rating system
and use the instrument accordingly. The
standard defines clearance and creepage
distances between critical parts within the
instrument. The degree of protection is
interpreted as a Category (“CAT”) rating,
plus a voltage limitation.
CAT ratings are assigned from I to IV,
although CAT I is nowadays of little
practical use. Instruments with higher
category ratings have better capacity to
withstand transients. The ratings indicate
the position of the circuit under test “downstream” from the transformer serving the
premises. Energy dissipates with
attenuation and therefore so does risk.
CAT IV is assigned to the utility feed from
the transformer to the service entrance,
CAT III is from the fuse panel to an outlet,
and CAT II is downstream of the outlet.
The rating doesn’t stop here, though, but
also must include a voltage limit for the
rated voltage of any system being tested,
because CAT rating is based on multiples
of system voltage. Some instruments list
a CAT rating but do not specify the voltage.
These should be avoided, as it is an
indication of shortcutting for economy in
design. To ensure safety, the operator
must use an instrument with a CAT rating
matching or exceeding that of the system
being worked on.
A recent study by a utility company has
indicated that using an instrument rated
one category lower than the application
requires increases the chances of an
accident by a factor of 30. Looked at
another way, this means that if 100
operators used instruments of the wrong
rating connected to live systems for one
hour per day over a 200-day year, a
dangerous situation is likely to occur every
18 months. These are not good odds for
anyone intending to spend a career in the
industry!
After CAT rating, it’s time to consider
the many other safety features that are
designed into quality equipment. A worthy
illustration relates to the common practice
of insulation testing. Years ago, poorly
designed test equipment would leave the
operator unprotected, and extra diligence
was required to avoid being shocked, or
worse. Remember, while many in the
industry take non-lethal “shocks” for
granted, they can produce unexpected
consequences like falling from a ladder or
catwalk or jostling a nearby person who
is working close to dangerous machinery.
Better to eliminate the issue altogether than
to try to live with it.
Testers now come with additional safeguards that didn’t exist years ago. A special
safety hazard exists with insulation
testing because the tester will charge up
the capacitance and absorption inherent
in the item being tested. This is a prime
example of how the test item can be an
unrecognized source of danger. Insulation
tests are always performed on de-energized
equipment. Therefore, given the safety
features of the tester itself, it’s easy for the
operator to become complacent and think
that he or she is working in a completely
safe environment. Not necessarily so!
The test item can store a lethal static
charge in its capacitance and polarization
of molecules in the insulating material. At
termination of the test, with the field
gradient provided by the tester now
removed, the charged item will generate
a relaxation or reabsorption current. The
operator does not want to become part of
this discharge circuit!
Older testers at best had a discharge
switch, if any protection at all. Operator
involvement was paramount, as it was easy
to forget to engage this switch. Modern
testers virtually eliminate the chance of
operator error by providing automatic safe
discharge. When such a tester senses
extraneous voltage (not provided by the
tester itself), visual and audible warnings
are engaged, and the actual voltage may
be automatically displayed, with flashing
symbols to ensure the operator’s attention.
A discharge circuit will then safely
dissipate the stored charge and monitor it
on the display, so that the operator will not
get across the terminals until the voltage
falls to less than 50 V. This warning circuit
will of course, operate at any time during
the course of a test, so that if the operator
accidentally connects to a live circuit, or
someone closes a breaker or flips a switch
while the test is in progress, the operator
will be immediately warned. But beware
of fuse protection; make sure it’s properly
integrated with other functions. In some
units, a blown fuse disables the protection
circuits; in others, it doesn’t. If a blown fuse
has disabled the alarms, the operator may
not realize what has happened and not be
warned if the tested equipment becomes
live.
One might also want to consider job
protection along with personal protection.
Before instruments were provided with
modern safeguards, it was common for
operators to cook not themselves but the
tester. Manufacturers of test equipment
were flooded with “warranty” returns that
had burn tracks across the terminal boards.
And their answer was invariably, “Sorry,
the warranty does not cover connection to
a live high voltage circuit.” Operators were
disregarding voltage indications, if they
existed at all, and proceeding to engage the
test button. As soon as they did, the tester
was ruined.
Well-designed modern testers remove this
source of anxiety and embarrassment by
disabling the test circuit in the presence of
extraneous voltage. The operator presses
the test button and nothing happens.
Phew! De-energize the circuit and proceed
with the test! One factor to be aware of,
however, is the possibility of low voltage
background noise, such as crosstalk on
communications circuits. Testing may have
to proceed in the presence of this, so the
tester must have an appropriate threshold
that will not disable it in such situations.
This article is continued in the next issue of
Electrical Tester. The second part will cover
further issues relating to the safe use of test
equipment and will include information
about test leads, multifunction testers and
ground testers.
The EGIL has landed!
Romain Douib
Product Marketing Manager
Featuring compact construction and
straightforward operation, Megger’s latest
EGIL circuit breaker analyser is suitable for
testing timing and travel on all breakers
that have a single interrupter per phase. In
addition, when used in conjunction with
the SDRM option and the new SDRM201
accessory, the instrument can also be used
to carry out static and dynamic resistance
measurements.
Although the EGIL is available at a very
attractive price, no compromises have been
made on its versatility or performance.
It is, therefore, an ideal choice for operators
of small power plants and for the maintenance of simple circuit breakers by power
distribution utilities.
To aid ease and speed of use, the EGIL has
a built-in sequencer that automatically runs
the selected breaker operating sequence
while making the appropriate measurements
and recording the results. In addition,
menu-driven procedures invoke sensible
default settings, thereby eliminating the
6
need for time-consuming pre-setting.
Megger’s EGIL test set offers three timing
channels for the circuit breaker main
contacts. Main contacts and pre-insertion
resistor contacts can be timed on the
same channel, with the results recorded
graphically and numerically on the integral
printed. Results are also shown numerically on
the instrument’s large easy-to-read display.
Two additional galvanically isolated
timing channels are provided for auxiliary
contacts. In addition, an analogue channel
is available as an option. While primarily
intended for monitoring contact motion,
this channel also finds many other
applications.
For EGIL test sets that have the SDRM
option installed, the SDRM201 module
extends the facilities to allow accurate
resistance measurements to be made on
circuit breaker contacts and other lowresistance devices. When used with the
test leads provided, the SDRM201 is
capable of supplying an instantaneous
current of 200 A DC, falling to 140 A after
one second. Multiple tests can be run with
only a short waiting time between them.
Megger ELECTRICAL TESTER October 2010
Used in conjunction with the SDRM201, the
EGIL test set supports dynamic resistance
measurement from 0 to 32 mΩ, and static
resistance measurement from 0 to 2 mΩ.
The inaccuracy of static resistance measurements is 2% ±2 µΩ or better.
To complement the latest models of its
EGIL circuit breaker analyser, Megger has
introduced a new version – R03A – of its
CABA Win computer-aided breaker analysis
software. Designed to run under Microsoft
Windows on a standard PC, this adds full
support for static and dynamic resistancemeasurements, new test plans for applications
where the EGIL is used with the SDRM201,
and 19 new timing parameters for multiple
operations.
www.megger.com
Photography by Damon Mount
Dr Stan Zurek
Magnetics Technical Specialist
All electric energy in the national grid is transformed
several times before it is delivered from the power
plant to the final user. The high-voltage power transformers
used are devices of considerable weight, size and cost.
However, the cost of a transformer relates not only to
materials and manufacturing, but also to the energy lost
over its lifetime. Read on to find how magnetic losses
affect economy and the environment.
All transformers dissipate some energy in the process
of transformation. Operating principles dictate that the
magnetic core is always magnetised to the same level,
regardless the load. This means that even when
transformer works with no load, the magnetic losses
are almost the same as when it is operating at full load.
At full load, the efficiency of large power transformers
can be very high – above 99% in some cases. However,
because the magnetic loss is practically fixed, efficiency
reduces with the load. Inevitably, under no load
conditions any transformer operates with 0% efficiency
– it consumes some energy to remain energised, but it
delivers no energy to any load.
The electricity transmission grid and all the transformers
in it are exposed to varying load. At night the load is
relatively light, so the transformers operate at much less
than nominal conditions, but they keep dissipating
exactly the same energy in magnetic losses.
Remembering that a power transformer can have a life
of 20 years or more, let’s now consider the hypothetical
case of a 10 MVA (10 MW) transformer that dissipates 1%
of the energy in magnetic losses. With a simple calculation,
we can conclude that over 20 years 614 MWh of energy
is lost and, if the price is 10p per kWh, the cost of the
losses is £61 k/€73 k/$90 k. This is just for a single
transformer – if we consider the case nationally, not to
mention globally, then we can see that the amount of
energy lost, the money associated with it and the
environmental impact are tremendous.
When transformers were first invented, magnetic cores
were made from so-called “soft iron”. This material was
quite lossy and, ever since, engineers and scientists have
been striving to improve efficiency by introducing a
number of technological modifications – to chemical
structure, mechanical processing, annealing, postprocessing, etc.
The diagram shows how these changes have helped to
reduce losses over time.
Magnetic losses,
finances and
environment
times lower than that of soft steel. This has had a very
significant impact on the overall efficiency of power
transformers.
In some cases, medium voltage power transformers are
still in use after 50 years of operation. Because these old
transformers were made from inferior magnetic material,
their losses are much higher and replacing them with
modern units would most likely bring noticeable savings
in the energy distribution network – a transformer made
50 years ago could lose 5-10 times more energy (for
magnetic loss) than a modern equivalent with the same
rating.
The production of the grain-oriented electrical steel is
a very complex process (perhaps a topic for a future
article). Further improvements are on the horizon, but
currently are too expensive to implement. However,
another approach is possible – different material can be
used.
10
core loss
at 50 Hz
1.5 T
(W/kg)
1
reduced
C
contentlarger
grains high temp.
annealing
decarburistai
addition
on
stress
of Si
Goss
coating domain
structur
refinemen
e
treduced
thickness
Hi-B
amorphous
0.1
1900
1950
2000
In the US many smaller distribution transformers are
made from material called “amorphous”. Its operating
flux density is slightly lower, but the losses are much
lower than in the case of electrical steel.
Amorphous transformers are slightly bigger, heavier, and
more expensive to make, but the energy savings of their
lifetime easily justify the larger capital cost. Yet in Europe
such transformers are still not very popular.
To ensure correct operation, several properties of
transformers must be tested regularly: electric insulation,
degradation of oil, turns and voltage ratio, etc. Higher
losses in the magnetic core can influence to some degree
the voltage ratio or the phase shifts between the test
signals. However, this is usually not a problem because
correctly designed transformer testers can cope with these
effects, even for older transformers.
Study and research continue into the problem of losses
in magnetic materials. Manufacturers of electrical steel
and amorphous ribbon sponsor many of these studies,
and there are a number of international “magnetic”
conferences where the newest developments are presented
and discussed. There is, for example, pressure from
industry for making acoustically quieter transformers.
Also, rapid development in Asian countries is making
electrical steel one of the hottest items on the market, so
that the manufacturers have serious problems in keeping
up with demand, despite the recent economic crisis.
One thing is, however, certain. In future we can expect
even better and more efficient magnetic cores. The
improvements might not be ground breaking, but every
single percentage point counts: for efficiency, for running
costs and for the environment.
Nowadays, the most commonly used material for magnetic
cores of power transformers is electrical steel, which is
a descendant of soft steel. However, the power loss of
the best grade of electrical steel now in use is around 50
www.megger.com
Megger ELECTRICAL TESTER October 2010 7
Q&A
In this issue, experts from the
Megger Technical Support Group
supply answers to the questions
they most frequently receive about
earth testing.
Q: Most of the time I find that clamp-type
testers provide a quick and convenient way
of measuring earth resistance. Where space
is tight, however, I sometimes have trouble
getting the clamp round the cable or earth
strap. Is there a solution?
A: The root of this problem is two fold most earth resistance testers have clamps
with a round aperture and a long body
length. While round clamps make life easier
for the instrument manufacturer, they’re
not really ideal for getting into inaccessible
places, or for clamping round earth straps,
which usually have a rectangular cross
section. However, Megger’s new DET14C
and DET24C models, have elliptical clamps
and a short body length making them
much more versatile. In addition, the
Megger instruments have a pre-hold key,
which makes them easier to use in restricted
locations as the meter can be simply
clamped around the cable or electrode and
then withdrawn before reading the display.
Q: After I’ve been using my earth clamp
meter for a while, especially in harsh
environments, I find that it starts to give
inconsistent and inaccurate results. Why is
this and what can I do about it?
A: This kind of problem is usually an
indication that the jaws of the clamp are
not closing properly. In many earth clamp
meters, the mating faces of the jaws take
the form of laminations that interlock when
the clamp is closed. This arrangement is
particularly susceptible to contamination –
it only takes a small particle of grit or dirt
to prevent the laminations from interlocking
and, when this happens, the meter will
not give accurate or reliable results. The
short-term solution is to carefully clean the
mating faces of the jaws. There is, however,
another problem associated with instruments
of this type – the laminations in the jaw
faces are thin and so are easy to damage.
When this happens, the only certain
remedy is to return the instrument to the
manufacturer for repair and recalibration.
Attempts to straighten the bent laminations
without the proper equipment are likely
to make things worse and, after an ad-hoc
“repair” of this type, there’s no way of
knowing whether the instrument is giving
accurate readings. A better and longer lasting
solution is to choose an earth clamp tester
that has flat jaw faces, as these are much
easier to keep clean and far less susceptible
to damage.
Q: What is the point of the ground leakage
current measurement feature that is offered
by some earth resistance clamp meters?
The story of
Multi-Amp
In the late 1970s, the pioneering SR range
was complemented by the company’s first
solid state relay test set, the SSR-78. This
evolved into the EPOCH series of protective
relay test sets in the 1980s, laying the
foundations for the development of
Megger’s latest MPRT and SMRT testers.
At every stage, the development process
was customer led. Multi-Amp was then –
as Megger is today – committed to talking
to its customers, discovering their needs,
and then applying its technical expertise
to meet those needs efficiently and costeffectively.
Bruce Buxkemper
VP, Megger Dallas
While Megger today is a single organization
that supplies one of the world’s widest and
most innovative ranges of portable electrical
test equipment and measuring instruments,
it continues to benefit greatly from the
unrivalled expertise it has acquired from
the many businesses that have, over the
years, joined the Megger family. One of
these is Multi-Amp, and here we provide a
brief insight into the fascinating history of
this company.
Multi-Amp was founded in 1951 by a
group of utility engineers who realised
that there was a need for reliable portable
instruments for testing at high currents.
This guided the choice of company name
– its products would test at multiple amps!
Among its early offerings was a very
popular, and for the time very compact,
high current test set designated the MS-1,
which was widely used by heavy industrial
companies for testing motor overload relays
and small circuit breakers.
Multi-Amp also introduced primary injection
test sets with current ratings as high as
100,000 A. These units were used principally
for testing large low voltage circuit breakers.
Arguably an even more significant factor
in the success of Multi-Amp was its
A: Measuring earth currents, preferably with
an instrument that gives true RMS readings,
is a good way of pre-empting potential
problems with earth resistance tests, as
large standing earth currents can affect
the accuracy of the results obtained. The
current measurements also provide
a very useful indication of the overall
dynamics of the earth system. In addition,
should it become necessary to disconnect
an electrode, it’s a very good idea to
measure the leakage current flowing.
A high leakage current will become a
dangerous live voltage when the cable is
disconnected. Again, Megger’s DET14C
and DET24C has been designed with this
in mind. The instrument has a very high
resistance to ‘noise’ current, and includes
an automatic firmware filter to smooth out
varying readings. Another additional user
benefit is the automatic current warning
which operates even when in resistance
range – just in case the user forgets to
measure it.
The Multi-Amp® PULSAR® Universal Protective Relay Test System represented the next
generation in protective relay testing.
pioneering work in the field of protective
relay testing. Until the middle of the 1960s,
few utilities recognised the importance
of such testing but then things changed
literally overnight. On November 5, 1965
a huge power blackout left 30 million
consumers in parts of the North-eastern
United States and Canada without electricity.
The initial cause of the problem was a
protective relay that failed to trip. Suddenly
protective relay testing moved to centre
stage.
At that time, Multi-Amp was under the
guidance of Ed Redlhammer, who was
an evangelist for better relay testing and
maintenance. Most relay testing in those
days was done using a variety of variable
autotransformers, resistive loads, ammeters,
voltmeters and other sundry equipment. As
a result, it often took longer to set up the
equipment than to carry out the test itself.
Ed’s insight was to produce a dedicated
relay test set that would eliminate the
need to use many separate items of
equipment, so that the test technician or
engineer could spend more time testing,
calibrating and servicing the relays, and a
lot less time in setting up and taking down
the test equipment.
This approach meant that Multi-Amp was
well placed to respond to the sudden
increase in demand for protective relay
testing after the blackout with its SR-51
protective relay test set. Taking advantage
of successive advances in technology, this
evolved in several stages into the SR-76,
and subsequently, the SR-90, which was
introduced in 1990 and finally discontinued
only this year. Technology moves on, and
even the best of instrument designs
eventually reach the end of their life!
After Ed Redlhammer retired as president
of Multi-Amp in the late 1980s, his role
was taken over by Ruben Esquivel, who
had fled Cuba when the Castro regime
came to power. He joined the company
as an assembler wiring high-current test
sets, and went to night school to earn his
electrical engineering degree. He then
continued his education to earn an MBA,
and ultimately became one of the co-owners
of Multi-Amp.
He retained his share of the ownership
until the company joined, among others,
AVO and Biddle to become part of the
present-day Megger organisation. This gave
the members of the Multi-Amp team access
to the resources they needed to drive their
ambitious development programme forward,
so that the company could continue to
produce equipment that would meet the
ever-increasing expectations of end users.
Megger continues to uphold the proud
traditions established by Multi-Amp, and
to this day retains its position as a leading
innovator and manufacturer of high current
test equipment and versatile protective
relay test sets.
Megger makes beautiful
music
Megger is certainly well known for instruments,
but it’s instruments of a rather different
kind that come to the fore when MELON
is in town! That’s because MELON is the
Megger Electric Light Orchestra – OK, the
N doesn’t actually stand for anything, but it
does provide the group with a catchy name
and a convenient logo!
Based at the Megger site in Taby, Sweden,
MELON is a group of Megger employees
with a shared interest in music, and is in
great demand to perform at sales conferences and other special events. Specialising mostly in popular rock music, though
occasionally writing and performing its
own songs, MELON has now been in the
vanguard of the test gear music scene for
over 20 years.
“There is a lot of interest in music at the
8
Taby site,” said MELON lead vocalist Stefan
Bornholm, “and, in fact, there are several
professional musicians working there. It’s
only natural that some of us should get
together to form our own group to entertain
our colleagues and customers. We toil on
test equipment by day, but by night we
make beautiful music together!”
The present day line up is Matz Öhlen,
Magnus Thieldgard, Stefan Bornholm, Peter
Fagerström, Klas Petterson and Conny
Edholm. Of these, Peter Fagerström and
Conny Edholm are founder members who
still retain their original enthusiasm for
Megger music making.
Megger may not yet be quite as well
known for its musical output as it is for its
test equipment but, given the enthusiasm
of the members of MELON, it is perhaps,
worth remembering that the world is still
waiting for Sweden to produce a worthy
successor to ABBA …
Megger ELECTRICAL TESTER October 2010
www.megger.com