Dependability of MV and HV protection devices

Purpose of the document

This document presents the various factors contributing to dependability of protection devices in Medium and High Voltage networks, together with the methods which can be implemented to meet dependability objectives.

It places special emphasis on:

• taking dependability into consideration at the design stage;
• the quality approach (software, qualification, manufacture) with techniques adapted to the constraints encountered in Medium and High Voltage;
• analysis of experience feedback.

This document complies with the techniques used in the nineties for designing the new Sepam protection range.

Protection devices

The main functions of a protection device are to detect network faults by monitoring various parameters (current, voltage….) and to transmit a circuit-breaker opening order should an abnormal situation be observed. A protection
device generally protects one of the various components of an electrical distribution substation, such as an incomer, a line feeder, a motor or a transformer.

In Medium and High Voltage, these devices are often incorporated in the equipment containing the circuit-breaker. Environmental constraints are then severe (temperature, vibration, electromagnetic disturbances).

AUTHOR: Schneider Electric expert | Marielle LEMAIRE