Cutler-Hammer HWT-500, Инструкция по эксплуатации

Страница: 15 / 45

I.B. 35-557
15 of 45
Trip Test – Switch positions
Network protector closed and set for automatic operation
FUNCTION Switch – “RELAY” position
I & PV Switch – AI position
Supp VM Switch – CA position
PHASE switch – 180 position
Single PH Test Switch – OFF position
SUPPLY Switch – 216 or 480 position depending on network system voltage
VARIAC – zero position
By increasing the VARIAC'S position, you can increase the reverse current value to the
desired value or to that value at which the network protector breaker will open its main
contacts. The network protector breaker should be tripped several times to ensure that the
operation is consistent.
When making the overall tripping test on a network protector breaker equipped with an
electro-mechanical de-sensitizing relay, connections to the test set, network protector
breaker, and power source as well as the switch positions remain the same. The reverse
current is slowly increased from zero until the relay trip contact makes. This is the reverse
current required to trip the breaker. As soon as the master relay trip contact makes, the
timing cycle of the time delay relay begins and the timing cycle is completed when the
breaker trips.
NOTE: When using the Type MPC series of solid state relays having a time delay setting,
the reverse current should be adjusted somewhat higher than its setting to ensure that the
trip logic is initiated. Timing should begin after the trip set point has been exceeded on the
Ammeter.