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Newsletter March 2012

Protection Against Permanent Over & Under Voltage
Hello ,

A permanent over voltage on the low voltage installation can occur due to accidental loss of neutral, faulty connection between phases (400Vac) instead of phase to neutral (230Vac) or presence of harmonics.

The permanent over voltage can result in :
  • Equipment failure
  • Overheating (reduction in length of life of equipment)
  • Electrical breakdown (risk of fire)
  • Deterioration in safety and protection of users.

Similarly, a permanent under voltage can also present a risk to the installation and equipment.

The over voltage auxiliary, MZ209, and combined over- and under-voltage auxiliary, MZ214, causes automatic opening of the electrical circuit by tripping the associated protection device (MCB, RCCB, RCBO) if there is a permanent over or under voltage detected on the network.