MESSKO® MPreC®
PrESSurE rEliEf DEviCE
SAfETy GuArANTEED.
M ES SKO iN S Tr u M E NTS
MESSKO ® MPreC ®
MESSKO® MPreC® –
SOMETHiNG yOu CAN rEly ON.
MESSKO® MPreC® are pressure relief devices for transformers and tap changers – in
Messko’s reputable high quality. Our objective has to improve and expand existing
functions. Demands on transformer equipment are rising steadily. As operating times
increase, reliable monitoring equipment becomes essential.
For your safety
„The increasing number of spurious release cases and leakage
in pressure relief devices results in a great deal of expenses for
us, through the resulting on-site service.” We have been listening
to such comments during more and more visits to customers
in recent years. That is reason enough for us to provide relief.
Quality you can feel
your fingers can tell you what differentiates Messko pressure
relief devices from the rest. No perceptible sharp edges; perfect
fits; high-quality materials.
Selected material
MESSKO® MPreC® Pressure Relief Device
Each and every part is tested for months and optimised in
our Messko and Mr testing laboratories. Perfectly adjusted
springs, optimised seals, tested components and functional
design demonstrate our know-how.
For more precision
if you want to protect your transformers and tap changers,
you can not settle for less than the highest quality. We
exclusively use high-quality materials – such as saltwaterproof, cast aluminium and anodised aluminium. We make
our KTl-coated springs according to EN 10270-1-SH. We
purposely avoid the use of galvanised, lacquered or plastic
components.
KTL–coated springs
Functionality you can count on.
If the maximum permissible opening pressure in the tap changer or transformer pressure
relief device is exceeded, the cover lifts and the device opens – within milliseconds.
When the pressure falls back below the opening pressure, the device closes once again.
Subsequently, the self-engaging signal pin just has to be pressed back into its normal
position. The optional signalling contacts are also reset.
With self protection
Our pressure relief device protects itself with a saltwaterproof cap. This cap shields all functional components from
external influences. This means that neither damage
nor impurities can influence its release performance.
With optimal characteristics
The internal signalling contacts and the valve disk are
protected from direct environmental influences through
its standard integrated cover. The outlet openings provide
for immediate, downward oil drainage. The indicator
pin is made of weather-resistant anodised aluminium.
It possesses two notches that prevent the pin from
falling back if it has not completely sprung up, e.g. in
the case of weak oil currents. This ensures its clear
release and engagement.
Signal pin, switching contact
During normal operation, a pressure relief device should
have a tight seal. However, in cases of malfunction, it must
release promptly and transmit the corresponding signal.
This prevents the transformer and/or tap changer from
suffering more serious damage. With MESSKO® MPreC®,
we have succeeded in optimising this core function.
For more safety
The switching contacts are situated inside the device; this
ensures absolute stability. In addition, they are also protected
from UV exposure, hail or hot gushes of oil. The internal seals
are slanted toward the valve disk. This enables them to seal
better and prevent spurious releases. Up to two further
contacts can be installed in the device or even retrofitted
without complication. With a reaction time of less than
2 ms – which corresponds to a defined pressure relief valve
lift of approx. 4 mm – the optional switching contacts are
forced to react.
With directed oil flow
The pressure relief device can be optional equipped with a
special cover to direct the hot oil to a containment device
in case of fault condition. The piping can be easy fitted to
the cover via the flanges (welding neck flange and flange
with an internal thread). The „oil directed” version of the
MESSKO® MPreC® helps to ensure employee safety, addresses
environmental concerns and avoid time and cost intensive
cleaning.
MESSKO® MPreC® „Oil directed”
PrODuCTiON WiTH AN EyE
fOr DETAil.
A product is only as good as its components. That’s why we
pay especial attention to detail in the production of individual
parts: We exclusively use high-quality materials and exceptional
production processes for the better protection of your transformer
or tap changer – and thus yourself.
It pays to be precise
Stringent quality testing is an integral part of the assembly
process with regard to the protection area of the transformer
and tap changers: Each device is checked for leaks using helium.
in addition, the „sealing” and „release” functions are inspected
on Messko‘s fully automated test bench. At the site of the final
inspection, multiple activation testing is performed. The response
characte-ristic curve – at the time of delivery and according to
the values specified by the customer – is recorded. These data
are accessible for each device sold even after a period of years.
Computer-controlled pressure test
Each device that leaves our production line has its
own „history”. At the start of each and every assembly
procedure, it is subjected to a helium leakage test.
A tradition of successful applications
The MESSKO® MPreC® pressure relief devices are primarily used
for tap changers or transformers. The MESSKO® MPreC® was
developed over months of dialogue with international OEMs
and end-user. As a result, we have achieved functional improvements in comparison to conventional systems. Whether a large
distribution transformer or a power transformer – the MESSKO®
MPreC® will reliably protect your equipment from extended
downtime. A separate report is written for each individual test.
This is a safety guarantee for our customers that our employees
confirm by signature.
Even more safety with the mobile
MESSKO® MPreC® test bench
MESSKO® MPreC® – mounted on an on-load tap-changer
Messko GmbH developed the mobile MESSKO® MPreC® test
bench as an additional safety package during the commissioning,
inspection and maintenance of pressure relief valves. Weighing
approx. 50 kg [110 lb], it is portable and can be used in the
laboratory, in the test bay and also during commissioning and
maintenance procedures. The test bench tests and logs the
accuracy and functional safety of pressure relief devices on
oil-filled transformers in the disassembled state.
MESSKO® MPreC® test bench
with pressure relief valve installed
MESSKO® MPreC® –
Pressure Relief Device.
Technical Data:
MESSKO® MPreC®
Materials
Flange
Seawater resistant cast aluminum
Standard cover
Aluminium, with powder coating in RAL 7033 or RAL 7038
Oil directed cover
Seawater resistant cast aluminum, with powder coating in RAL 7033 or RAL 7038,
cover and flange sealings Nitrile (NBR), internal sealing Fluorocarbon rubber FKM (Viton®)
Valve head
Stainless steel (1.4301)
Sealing
Nitrile (NBR); Fluorocarbon rubber FKM (Viton®) (optional)
Springs
Spring steel acc. EN 10270-1-SH, synthetic coated (cathodic corrosion protection)
Indicator pin
Seawater resistant aluminum, red or blue anodized
Semaphore
Stainless steel with acrylic coating in RAL 1026, Lime-yellow
Bleed screw
Stainless steel for oil bleeding, optional without bleed screw
Dimensions
Mounting
Ø 235 mm (Ø 9.25”) hole circle with 6 fixing holes Ø 15.5 mm (Ø 0.61”)
Cover
Ø 291 mm (Ø 11.46”)
Height
Position “OPERATION”: 184.5 mm (7.26”); position “ALARM”: 234.5 mm (9.23”)
With semaphore: Position “OPERATION”: 230 mm (9.06”); position “ALARM”: 340 mm (13.39”)
With oil-directed cover: Position “OPERATION”: 196.5 mm (7.74”); position “ALARM”: 246.5 mm (9.71”)
Weight
With standard cover: approx. 6 kg (13 lb)
With oil-directed cover: approx.13 kg (29 lb)
Mounting gasket
Ø 200 x Ø 178.5 x 4.25 (Ø 7.87” x Ø 7.03” x 0.17”), nitrile (optional available)
Operating temperatures
Ambient
–50 °C to +80 °C / -58 °F to +176 °F (mechanical); –40 °C to +80 °C / -40 °F to +176 °F (micro-switches)
Oil
-30 °C to +120 °C / -22 °F to +248 °F
Micro-switches
Housing material
Seawater resistant cast aluminum
Contacts
Per micro-swith 1 x NO, 1 x NC; galvanically isolated
Connection types
Cable gland connection with 1 x or 2 x M 20 x 1.5 cable gland
Terminal Box with 1 x or 2 x M 25 x 1.5 cable gland
ANSI connector with 16 AWG, SOOW cable, available in different lengths
Utilization category
IEC 60947-5-1: AC-15/DC-13
Contact load
As per IEC 60947-5-1: AC: 240 V/3 A; 120 V/6 A
DC: 250 V/1.1 A; 125 V/2.2 A
Max. continious current
10 A
Rated insualtion voltage
AC: 2,5 kV/1 min.
Pressure ranges:
Type
PSI
Bar
kPa
LMPRD 04
4 PSI ± 1
0.28 bar
28 kPa
LMPRD 06
6 PSI ± 1
0.41 bar
41 kPa
LMPRD 08
8 PSI ± 1
0.55 bar
55 kPa
LMPRD 10
10 PSI ± 1
0.69 bar
69 kPa
LMPRD 12
12 PSI ± 1
0.83 bar
83 kPa
LMPRD 15
15 PSI ± 2
1.03 bar
103 kPa
LMPRD 20
20 PSI ± 2
1.38 bar
138 kPa
LMPRD 25
25 PSI ± 2
1.72 bar
172 kPa
LMPRD 30
30 PSI ± 2
2.07 bar
207 kPa
Messko GmbH
Gewerbegebiet An den Drei Hasen
Messko-Platz 1
61440 Oberursel, Germany
Phone: +49 6171 6398 0
fax: +49 6171 6398 98
E-mail: info@messko.com
www.messko.com
Please note:
The information contained in all of our publications
may differ in detail from the actual equipment delivered.
We reserve the right to make changes without notice.
iN2065/06/01 EN – MESSKO® MPreC® –
MS99093105 – 03/15 – ©Messko GmbH 2015