MPreC Pressure Control stands for PRD for transformers and OLTC

  • Hood with inlaid micro-switches
  • Defined valve stroke of approx. 4mm up to forced activation of the main switching contacts
  • Weather-resistant aluminum signal pin with two notches prevents roll-back of an incompletely extended pin
  • KTL-coated springs (cathodic corrosion protection) according to DIN 2095
  • Opens within 2ms; closes within 70ms
  • Seawater-resistant cover


The standard protective cover protects the internal micro switches and the springs against outside influences. In addition, it ensures that the oil flows out in a defined way during operation. The cover is made of sea-water-resistant aluminum. When the operating pressure is reached, the plate lifts up to create an opening through which gas or oil can escape. The aluminum signal pin raises and operates the micro switches. The defined stroke allows the contacts to react within 2 ms. The pin adjusts its position while the pressure relief device closes securely.

Messko Pressure Relief Devices are available in a range from 5 to 30PSI (0.41 to 2.07bar). Electrical connection can be implemented with cable glands or a terminal box. ANSI and Westinghouse connectors are also available for the North American market.

The Pressure Relief Devices is also available with an oil-directed cover.