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Surge Protection Devices for LV Systems
Australasia
A technical overview
© 2007 Eaton Corporation. All rights reserved.
© 2008 Eaton Corporation. All rights reserved.
Last Updated 15/08/07
Who are we, what do we do?
 Part of Eaton group. EPQS / Powerware.
 Was Total Power Systems, acquired by Invensys / Powerware.
 New product design to AS/NZS and IEC standards. Specialising in
TVSS / SPD devices.
 26 man years of TVSS product development and delivery.
 Specialised secure power applications to Navy, Air force, Army, Data
Centres.
 Specialised TVSS solutions to major commercial operations. Optus,
NSW Health, QLD Health, Switchboard manufacturers, Mining
industry. Australia, New Zealand, Vietnam, Sri Lanka, Africa, Europe.
 54 man years in electrical design and manufacture across 2 people
and 5 multinational corporations.
 R&D lab Mascot limit 4kA/8kV 8/20us with access to R&D lab China
up to 120kA 10/350us. 8/20us. 1.2/50us waveforms.
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we blow things
up for a living…
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SPD Industry Myth
Lightning strikes can produce in upwards of 200 000 amps of surge current.
Therefore 200 000 amps can flow into electrical distribution systems.
Fact!
A maximum of 20kV and 10kA gets induced into electrical distribution
systems from a lightning event. Voltages and currents in excess of this will
cause irreparable damage. Cable insulation would fail before the surge
could even get into the building.
Source: ANSI/IEEE C62.41
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What is a Surge?
A surge is a random, short burst of excess electrical energy to a system.
Also referred to as a transient, impulse or spike, these electrical
disturbances can damage or even destroy sensitive microprocessorbased equipment. Its duration is in the micro and millisecond time frame.
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Why do I need surge protection?
 Electrical equipment design moving to reduce costs and relying on
specified mains voltages being maintained to supply standards.
 Most equipment is now designed in accordance with regulated surge
protection standards (especially Europe).
 Utility suppliers can no longer guarantee absolutely error free power.
 Trying to deal with excess energy at the final point of entry into your load
is the wrong place to deal with it.
 Increases the longevity of your investment.
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Where do they come from?
80% of transients are generated from internal sources such as load
switching, motors starting up or even turning on air conditioning systems.
Internal
External
The other 20% of transients are generated from external sources such
as lightning strikes and power company grid switching.
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Causes - Ultimate sources
 Lightning strikes
 Electrical switching
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Standards.
 There is a standard for everything. No need to re invent the wheel.
Let the standards do the work for you.
 Starts with EN LV directives, then flows to surge risk assessment
standards, then to equipment standards, then to test standards, then to
reporting standards.
 Some standards you may here about are:
 ANSI/IEEE C62.41. Low voltage surge protection, waveform, test
and current standards and limits.
 Test waveforms. Each Category / Class type has a different
standardised test waveform.
 10/350us is Class I
 8/20us is Class II short circuit.
 1.2/50us is Class II open circuit.
 100khz Ring wave is Class III only.
 Equipment standard will determine the correct waveform to be used.
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Standards.
 AS/NZS1768 Region-specific standards - Risk assessment.
 IEC61643, UL1449 Equipment standards.
 AS/NZS 3000:2007 Wiring rules. Appendix F.
 They do overlap but don’t confuse them.
 In Australia, New Zealand and most of Asia, AS/NZS1768,
IEC61643-1 and ANSI/IEEE C62.41 are all you will ever need.
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Protection Zones (ANSI/IEEE)
Category C (15kA)
Point-of-Entry / Service
Entrance
Category B (3kA)
Major sub mains & short
final sub circuits
Category A (200A)
Long final sub circuits &
power outlets
There are two more
categories, which simply
extend the Category C
Category D (30kA)
High exposure such as
elevated overhead lines
Category E (70kA)
Elevated very high
exposure & critical load
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Solutions
Protection zones – IEC61000 series European
standards
Class I – Outdoor, “direct strike” Class I devices. Extreme to high risk zone.
Class II – Indoor, induced strike Class II devices. High to medium risk zone.
Class III – Final circuit, equipment, Class III devices. Medium to low risk zone.
ANSI/IEEE C62.41. U.S. Standards
Category E – External elevated supply point. Extreme risk zone. Direct strike.
Category D – External supply point. Extreme risk zone. Direct and induced surge.
Category C – Point-of-entry High risk zone. Direct and induced surge.
Category B – Sub-SWB or intermediate circuit. Medium risk zone. Induced surge.
Category A – Final circuit, equipment. Low risk zone. Induced surge.
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Solutions
Protection technologies
Each Category / Class uses different types of technology in different
ways to manage the harmful energy levels .
 Surge diverters – MOV, Spark gaps, Gas arrestors. Usually parallel
connected.
 Surge Filters – creating a a protection zone by limiting current through
inductors and using high frequency clipping via capacitors to improve
noise rejection. Usually series connected
 Each technology has differing electrical attributes and no one
technology can be used in all situations.
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Protection Technologies
Metal Oxide Varistors (MOV)
Gas Discharge Tube
Suit all zones except direct strike.
Suit all zones but must not be
connected across Line –
Neutral or Earth in some
circumstances. Has follow
current.
Silicon Avalanche Diode (SAD)
Suits lower risk zones only
Spark Gaps
Suits high risk zones
only
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Surge Diverters
Surge Diverters are parallel connected devices that provide shunt
diversion only and are typically used at the point-of-entry to a facility.
These devices offer coarse protection, making them suitable as the
primary defense against power surges.
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Surge Filters
Surge Filters are series connected devices that provide fine
protection. They are usually installed closer to the load to act as a
second line of defense, providing further surge reduction, current limiting
& noise filtering for sensitive electrical equipment.
Note: The
inductor
provides current
limiting of
surges to load
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Cascading
•
SPD’s are designed to work as part of a complete protection system.
•
They are typically installed as PRIMARY and SECONDARY devices (
see standards recommendations ). This is known as Cascading and is
an important concept in surge protection. No one device can do
everything from point of entry to final sub circuit.
•
You may have up to 3 levels of protection in a complete system. Ie. A
Class I device at high risk point, Class II device at POE and Class III
device on GPO.
•
In most cases you will need at least 1 x Class II and 1 x Class III device.
OR 1 x Class I and 1 x Class II device.
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Protection modes
•
Protection modes refers to the way in which the SPD controls harmful
energy.
•
There are 4 modes: L-N, L-L, L-E, N-E.
•
L-N & L-L are referred to as Differential modes.
•
L-E, N-E are referred to as Common modes.
•
Choosing the right modes for your application depends on your electrical
system characteristics. Ie TT, TN, TN-C, TN-CS.
•
Most systems in Australia are TN type. Ie Neutral is derived from Earth at
the user point of entry. ( commonly called the M.E.N. link ).
•
Whatever modes you select the harmful energy must make its way
back to Earth SOMEWHERE. So make the control path easy for the
energy to get to earth and dissipate.
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System Design
Installation issues.
1.
Physical location.
2.
Electrical location.
3.
Safety disconnectors.
4.
Cable length and type.
5.
Earthing.
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Installation Issues
Physical location.
1.
As close as possible to Main Switch or metering point – within Main
SWB if possible.
2.
Accessible for maintenance – extra isolation switch.
3.
Environmentally benign – no excess moisture or heat.
4.
Personal safety.
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Installation Issues
Electrical location.
1.
Locate at a point close to the Main Isolating Switch, allowing close
access to all phase and N/PE conductors.
2.
If N/PE is remote from phase conductors, consider extending all
conductors to an intermediate point.
3.
Earthing point (for Main SWBs) must be located within a short
distance.
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Installation Issues
Safety disconnector.
1.
Preferred to use HRC Gg/Gl fuses, not CBs. CBs break down in
instant high current waveforms. They can either nuisance trip or be
partly damaged causing premature MTBF failure. Fuses are much
better at conducting rapid transients. If you must use an MCB then
be aware that the total circuit performance may not equal that of the
SPD. It will still work, but its not as efficient.
2.
For medium & high-current services (250-3000A), use the maximum
fuse as recommended by manufacturer.
3.
For low-current services (<250A), the fuse rating will limit surge
capacity.
4.
For very low-current services (<80A), it may be necessary to rely on
line fuses.
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Installation Issues
Cable length and type.
Cable voltage drop is the biggest loss.
1kA/1m ~ 150V @ 8/20us >> Cat C (15kA)/1m ~ 2250V @ 8/20us
That’s a lot of stress on the cable BEFORE the SPD gets going. Make
the SPD work for you.
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Installation Issues
Cable length and type continued.
1.
Cable length (inductance) is the biggest issue.
2.
Multiple, small cables better than one large cable.
3.
Busbars are much preferred, where applicable.
4.
Keep total connection length below 0.5m on any cable and always
tie cables tightly together.
5.
Try to keep surge voltage drop to <1kV/cable.
6.
Do not loop extra cable!
7.
Keep input ,“ DIRTY “ power separated from output, “ CLEAN”
power. Do not bundle together.
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Installation Issues
Earthing.
1.
Site earth must be as good as possible.
2.
Busbars should be used for runs >3m (remember 1kA/m = 1kV!)
3.
Use a ‘star’ (or ‘single-point’) earthing system in all cases -do not
daisy-chain earth systems.
4.
Always interconnect sub-SWB earths with adjacent building metal.
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RCD’S in a Surge Circuit
 RCD’s are designed to detect current flow between active conductors
and earth. When a SPD shunts to earth an RCD will most likely trip.
Most L-N shunts should have no impact as long as MEN link is close.
 SPD’s should be installed UPSTREAM of any RCD.
 Latest wiring rules add another level of complexity to the solution.
 There is no avoiding the physics.
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Installation Issues
Why we must try hard(er)
All SPD systems have appreciable losses.
“Weak links” concentrate energy loss.
…because lightning doesn’t care.
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Selecting a TVSS product
Specify what you really need. Avoid ‘cut and pasting’
other manufacturer’s specifications. Let the SPD
equipment standard do the work for you.
 What to look for.
 “Must have” features.
 “Nice to have” features.
 Coordinating with upstream and downstream infrastructure.
… BUT DON’T OVERDO IT!
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Selecting a SPD product
What to look for (questions to ask customers).
Â
Specify a standard. It does the hard work for you. Don’t invent your
own. IEC61643-1, AS/NZS 1768, ANSI/IEEE C62.41 are more than
you will ever need.
Â
Service voltage and type – 1 or 3-phase, 240/415V, local M.E.N.
Â
What are we protecting? – Specific equipment or the entire
building?
Â
Proposed location of SPD – At M.E.N. point or subSWB/equipment?
Â
Maintenance requirements – Repair or replacement shouldn’t
require site to be blacked-out.
Â
Likelihood of damage – if SPD is affected by service faults.
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Selecting a SPD product
“Must-have” features (questions to ask customers).
Â
Look for Vpl, MCOV, Inom, Imax, SCW specs. Make sure they are
quoted in each mode of operation. Lowest, fastest and largest does
not always mean the best. There are traps.
Â
There is a benchmark for each specification.
Â
Service rating determines maximum surge current. Small services
(63-80A) are incapable of Isurge > 40kA without the supply fuse(s)
rupturing. Do not overspecify.
Â
Common-mode protection is only required for applications remote
from the M.E.N. point.
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Selecting a SPD product
“Nice to have” features (questions to ask customers).
Â
Alarms – few people monitor them (except telcos etc.)
Â
Displays – More for show than ‘go’. A clear and concise “Fault”
indication is better than taking bets on longevity.
Â
IP ratings – if a customer asks for IP65, ask why – pointing out that
SPD equipment should never be ‘stand alone’.
Â
User-replaceable modules – “users” should never work on live
equipment. When damaged, TVSS equipment should be replaced in
it’s entirety, not 1 phase at a time.
Â
SPD certifications – IEC61643-1 should be adequate!
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Selecting a SPD product
Coordinating with upstream and downstream
infrastructure (questions to ask customers).
 If sizing primary protection, what secondary protection (if any) is
intended? Conversely with secondary (sub-SWB) protection.
 Service fusing level and fault rating affect SPD capability.
 Position, position, position – is the device being protected close to it’s
protection? If not, use an auxiliary protector at the load.
 For filters, what is the load? If the load has high current distortion,
consider using shunt SPD instead.
 Filters draw current! Allow for 5% filter current (I.e. 63A filter = 3.15A
>> 66.15A supply current OR 59.5A load current.
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SPD product certification
 Who cares? (You should. Check for standards compliance and test
evidence in specs. IEC standards reflect more closely our low voltage
system than UL standards)
 Be careful about performance claims. Not all claims are valid or even
meaningful.
 Why is UL1449 irrelevant in Australia ?
 Understanding some of the characteristics:
 MCOV, TOV, VPL, Inom, Imax, SCW
 Standardised specifications in IEC 61643-1. This standard covers all
aspects of safety, test waveform compliance, performance reporting
rules etc.
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Load protection guarantee claims
Â
It’s almost impossible to GUARANTEE a failsafe outcome. There are
limits to all semiconductor technologies. Such guarantee’s are really
about RISK REDUCTION. They also have lots of limiting conditions.
And for good reason.
Â
Common installation faults. Devices with multiple ports ( power, data,
phone, video etc ) all rely on common earth point VIA the SPD. If even
one port is not DIRECTLY connected to the SPD then it will almost
certainly fail. RTBM.
Â
Learn to scale your risk. 100kA at a 10A GPO ???
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Good installations vs poor installations
Actually, there are no “really good”
installations…
… but we can try to make them as ‘good’ as
possible.
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SPD Product Range
© 2007 Eaton Corporation. All rights reserved.
© 2008 Eaton Corporation. All rights reserved.
Last Updated 15/08/07
Eaton SPD Products
DIN Rail & Panel
Mount Surge
Protection
Portable
Surge Filters
Dataline & Rack Mount
Protection
Premium 3 Phase
Diverters & Filters
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Surge Diverters
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Three Phase Surge Diverter
MSDi
Key Features:
Â
Surge current rating = 60kA/ph Inom &
200kA/ph Imax
Â
Point-of-entry protection
Â
LED Bar graph display on each phase
Â
Enclosed in IP24 painted steel cabinet
Â
Protection fail alarm relay
Surge Category:
Â
Category E, D & C locations
Â
Class II device
Application:
Â
Main protection for industrial plants, commercial
buildings and process control systems
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QuickmovTM Surge Diverter
QuickmovTM
SPD50NGi
Key Features:
Key Features:
Â
Fits any QuicklagTM load centre
Â
Â
Surge current rating = 30kA
Inom & 60kA Imax
Compact N-E protection
solution
Â
Surge current rating –
50kA Inom & 70kA Imax
Â
Class II device
Â
Compatible with most
switchboards
Â
In-built HRC fuse, with the
added safety of integrated
thermal protection.
Surge Category:
Â
Category C & B locations
Â
Class II device
Application:
Â
Industrial sites, commercial
sites, factories, schools and
process control systems
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Din Rail Surge Diverters
SPDi din rail series
Key Features:
Â
SPDV60 – 1 Pole 30kA Inom, 60kA Imax
Â
SPD120i – 1 Phase 50kA Inom, 100kA Imax
Â
SPD3i – 3 Phase 20kA/Ph Inom, 40kA/Ph Imax
Â
Alarm contacts as standard
Surge Category:
Â
Category C & B locations
Â
Class II device
Application:
Â
Industrial sites, commercial sites,
telecommunication, medical and
process control systems
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Surge Filters
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3 Phase Premium Power Filter
PPFi
Key Features:
Â
Gear tray versions available
Â
Imax rating up to 240kA
Â
EN certified EMI/RFI Filter
Â
Can be customised to specification
Â
Enclosed in IP24 painted steel cabinet
Â
Panel-mounted mimic display and
alarm relay outputs
Surge Category:
Â
Category D, C & B locations
Â
Class II device
Application:
Â
Multi-storey buildings, hospitals, IT
datacentres and airport facilities.
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1 & 3 Ph 40-63A Surge Filter
MSFi
Key Features:
Â
Surge rating Inom = 60kA and Imax = 160kA
Â
Enclosed in IP24 paint steel housing
Â
Available in 40 or 63 Amp ratings
Â
Protection fail alarm relay
Â
Front panel status indicators
Surge Category:
Â
Category D, C & B locations
Â
Class II device
Application:
Â
Telecommunication systems, process &
control systems, small commercial offices
& industrial sites
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Compact Surge Filters
CSFi
DSFi
Key Features:
Key Features:
Â
3-25Amp 240V AC
Â
5-32Amp 240V AC
Â
Surge rating Inom = 10kA
and Imax = 25kA
Â
Surge rating Inom = 15kA and
Imax = 40kA
Â
Can be used as stand alone
solution for units and small
offices
Â
Dual stage filter
Â
Can be used as stand alone
solution in lightly exposed
sites
Surge Category:
Â
IP20 painted steel housing
Â
Surge Category:
Â
Protection Fail Alarm Relay
Category B & some C
locations
Â
Category B & some C
locations
Application:
Â
Class II device
Â
Application:
Â
Class II device
PLC’s, computer systems,
servers, mission critical circuits
Â
UPS systems, rectifiers, AV
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circuits in
clubs & hotels 45
Portable Surge Filters
POD & POD+
SSFi
Key Features:
Key Features:
Â
60kA surge protection rating
Â
Â
Handles more than 1 Million
surges *(AS1768 Cat A ring wave 200 Amps)
Surge rating Inom = 10kA
and Imax = 25kA
Â
Surge suppression and
filtering in a single
package
Â
Small footprint, modular
design
Â
Enclosed in IP50 painted
metal housing
Â
6 or 8 extra wide socket spacing
Â
Ideal for data, AV, phone line
and Cable TV protection
Surge Category:
Â
Â
Category A locations
(unprotected or lightly protected
sites)
Class III device
Application:
Â
Home, office, entertainment
systems, laboratories, computer
systems
Surge Category:
Â
Category A locations
Â
Class III device
Application:
Â
Industrial printers, servers,
plug-in UPS and POS
systems
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Data and Rack Mount Protection
Rack Mount
Data & Network
Key Features:
Key Features:
Â
Â
Protects all CAT5
network devices
Â
Protects all 8 wires
of a CAT5 cable
Â
Simple to install
Â
Unique
mounting
system
Rigid steel
case
PWSF8R-U
Â
22.5kA Surge
Rating
Â
Does not effect
network traffic
Â
Category A,
Class III
device
Â
Category A.
Class III devices
ECAT6PPC
ERAK16EC5
EMTJPOE60V
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Category C / Class II products
SPDi
SPFi
Category C
(15kA)
MSDi
MSFi
Quickmov
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Category B / Class II products
SPDi
Category B
SPFi
CSFi
(3kA)
MSFi
DSFi
Quickmov
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Category A / Class III products
SSFi
SF8RU
Category A
(200A)
ERAK16EC5
EMTJPOE60V
50
POD
50
If you need assistance or advice on design
or specifications:
Mike Hale. 9693 4350
mikejhale@eaton.com
Ryan Nguyen. 9693 9459
ryannguyen@eaton.com
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