MESSKO® MPREC®

Pressure relief device for transformers and on-load tap-changers

The MESSKO® MPREC® pressure relief device protects distribution and power transformers, electric coils and tap changers reliably and safely in the event of sudden pressure increases. Special variants for directed oil flow and applications fulfill nearly all requirements in the offshore area or in wind turbines. When the defined response pressure (4 to 30 psi) is reached, the valve plates and signal pin lift and the main switching contacts are triggered within 2 milliseconds. The proven design and perfectly coordinated springs ensure that the pressure relief device closes again securely.

Your Advantages at a Glance

Hood with interior micro-switches
Opens within 2 ms; closes within 70 ms
Suitable for wind turbines
Defined valve stroke of approx. 4 mm up to forced activation of the main switching contacts
Weatherproof aluminum signal pin with two notches, self-locking
Steel springs in accordance with EN 10270-1-SH, plastic-coated, customer-specific part painting (KTL)
Seawater-resistant hood

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Product Information

Technical data Pressure range Downloads

Materials
Flange	Seawater-resistant cast aluminum
Standard cover	Seawater-resistant aluminum with RAL 7033 or RAL 7038 powder coating
Oil-directed cover	Seawater-resistant cast aluminum with RAL 7033 or RAL 7038 powder coating
Corrosion protection	In accordance with ISO 12944-9:2018, available in C4H or CX (optional)
Valve disk	Rust-proof steel (1.4301)
Sealing material	Perbunan (NBR) for mineral oils; optional fluorocarbon rubber FKM (Viton®) for alternative insulating media
Springs	Spring steel in accordance with EN 10270-1-SH, plastic-coated customer-specific part painting (KTL)
Indicator pin	Seawater-resistant aluminum, red (mineral oil) or blue (alternative coolant) anodized
Semaphore	Stainless steel with RAL 1026 acrylic resin coating
Vent screw	Stainless steel for oil bleeding in accordance with IEC 60076-22-1
Dimensions
Cover	Ø 291 mm (Ø 11.46"), bolt circle Ø 235 mm (Ø 9.25"); 6 drilled holes each Ø 15.5 mm (Ø 0.61")
Installation height	With standard cover: 234.5 mm (9.23") / with semaphore: 340 mm (13.39")
With oil-directed cover	246.5 mm (9.71") / with semaphore: 442 mm (13.46")
Weight	With standard cover: approx. 6 kg (13 lbs.), with oil-directed cover: approx. 13 kg (29 lbs.)
Mounting gasket (optional)	Ø 200 x Ø 178.5 x 4.25 (Ø 7.87" x Ø 7.03" x 0.17")
Operating Temperatures
Environment	-50°C to + 80°C (mechanical); -40°C to +80°C (micro-switch)
Oil	-30°C to +120°C
MICRO-SWITCHES
Number of switches	Up to 2 switches, 1x NO each, 1x NC each; electrically isolated
Contact load	As per IEC 60947-5-1: AC-15: 240 V / 3 A; 120 V / 6 A; DC-13: 250 V / 1.1 A; 125 V / 2.2 A
Max. continuous current	10 A
Rated insulation voltage	AC: 2.5 kV/1 min.
Degree of protection	IP66
Connection designs	Cable connection with 1x or 2x M20x1.5 cable glands Terminal box with 1x or 2x M25x1.5 cable glands ANSI connector with 16 AWG, SOOW cable; available in various lengths

Type	LMPRD 04	LMPRD 06	LMPRD 08	LMPRD 10	LMPRD 12	LMPRD 15	LMPRD 20	LMPRD 25	LMPRD 30
PSI	4 PSI ± 1	6 PSI ± 1	8 PSI ± 1	10 PSI ± 1	12 PSI ± 1	15 PSI ± 1	20 PSI ± 1	25 PSI ± 1	30 PSI ± 1
Bar	0.28 bar	0.41 bar	0.55 bar	0.69 bar	0.83 bar	1.03 bar	1.38 bar	1.72 bar	2.07 bar
kPa	28 kPa	41 kPa	55 kPa	69 kPa	83 kPa	103 kPa	138 kPa	172 kPa	207 kPa

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MESSKO® MPREC®

Your Advantages at a Glance

Product Information

Materials

Dimensions

Operating Temperatures

MICRO-SWITCHES

Materials

Dimensions

Operating Temperatures

MICRO-SWITCHES

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