MVAJ 10. MVAJ 20

When configured for high burden applications, the burden is

either cut off or is economised to a low figure after a 40-60 ms

time delay. Due to the greater minimum operating current, the

high burden application also permits the use of supervision relays

such as type MVAX 11. where the wiring is at risk. The 40- 60 ms

time delay ensures reliable operation of series elements such as

type MCAA repeat relays.

Type MVAJ 102 relay is specifically designed for applications

requiring a tripping relay which is self-resetting after a nominal

delay of 2.5 seconds. This relay may be used, for example, for

inter-tripping between higher voltage and low voltage circuit

breakers of a large 3-phase power transformer.

This may become necessary when the high voltage circuit

breaker is tripped after a heavy internal fault by protection

which cannot conveniently provide an auxiliary contact with a

dwell time long enough to ensure correct tripping of the low

voltage circuit-breaker.

Typically, the relay is initiated by transformer protection, such as

overall protection, restricted earth fault and Bucholz relays, in

arrangements where both the HV and LV circuit-breakers are to

be tripped simultaneously.

The HV breaker may be expected to trip more quickly than the LV

breaker so the tripping signal is maintained by the delayed reset.

This ensures complete clearance by the LV circuit-breaker, even

though the fault may have been cleared largely by the HV breaker

and the protection has started to reset.