Voltage Selection Relay Block MVAP22

Type : MVAP22

Features :

1. Detects voltage circuit failures
2. Can be used to switch to an alternative supply if the main supply fails
3. Compact design
4. Mechanically stableApplication :
   1. A typical application as a voltage selection relay is the automatic connection of metering equipment to an alternative supply if the normal or preferred supply fails. As a fuse failure relay it will monitor the output of a voltage transformer and give an alarm or disconnect protection circuits for VT fuse failure.
   2. The relay monitors the three phase voltage supply and operates if the supply is interrupted or becomes
      unbalanced due to failure of the voltage transformers primary or secondary fuses.

   This Voltage Selection Relay block is easily insert in your schematic diagram and connect as you like way.                                                                                                                                                                                                      A is fed from a resistance/ capacitance network which under healthy conditions with negligible harmonics has zero output. An operating voltage appears across the coils of unit A when the secondary voltages become unbalanced due to loss of any one primary or secondary phase. Unit B has six changeover contacts for voltage selection and is normally energised via the normally closed contact on unit A from two phases of the supply. Unit B drops off on operation of unit A, on complete loss of supply, or on loss of two primary or secondary phases. If three limb core type star connected voltage transformers are used, the relay will not operate correctly if the star points of the primary windings are connected to neutral or earth.