GE MVAJ 31 Tripping and Control Relays

The MVAJ31 is built on similar lines to the MVAA 16 and followed by an MVAA11 using a

mixture of standard  and heavy duty contacts. In order to meet the capacitor discharge

test some resistors and internally  wired contacts  have been added.

Operation

When the relay is switched  the high speed unit will operate inside 4 milliseconds followed

shortly after by the MVAA. The outgoing contacts of the two units are in parallel so to give

high speed and the breaking capacity. By using a low value resistor in parallel the 10 uF

capacitor discharge is overcome. As the MVAA 11 operates it switches out the MVAA16

and parallel resistor to lower the burden to an acceptable level.

Results

Pick up range: 87.5-  137.5V

Pick up time: 4 milliseconds  over voltage range

Drop off time: 15 milliseconds

Initial Burden  180 watts at 137.5 volts for 4 milliseconds  reducing  to 65 watts and finally

6.8 watts after 15 milliseconds.

Case Size

The relay may be housed in either  MIDOS  size 3 or size 4 cases. The heavy duty contacts

are as for the MYAA II  so the same contact duties can be claimed.  All other outgoing

contacts  are as standard  MVAAs.

Key Benefits

• High speed operation

• High and low burden alternatives

• Models surge proof against high capacitance discharge currents in the dc supply system,

are available

• Control relays immune to AC can be supplied