I.L. 32-693 A
Page 8
Effective September 1998
4.10 CHECKING GROUND DELAY TIME
Note: Zone Selective Interlocking essentially disables
Ground Delay Time. This function is provided as a
standard feature on all Magnum Trip Units. To test the
Ground Delay Time when the breaker is removed
beyond the test position in the switchgear, the zone
interlock shorting plug must be utilized (
see Figure 5
).
Without this, all Ground Delay Time values will be
minimum.
1.
Set desired Ground Fault Time setting on Trip Unit.
2.
Set the Test Kit as follows:
2A.
TIMER to “OFF”.
2B.
CURRENT ADJUSTMENT to “ZERO”.
2C.
HI-LO AMPS switch to “LO AMPS”.
3.
If the breaker secondary contacts are not connected to
the switchgear Zone Interlock wiring (breaker is
beyond the test position), install the Zone Interlock
Defeat adapter.
4.
While holding the
GROUND TEST momentary switch
and the
CALIB switch in the down positions, turn
CURRENT ADJUSTMENT knob to get a current above
pickup value (see Table 1 and Step 8 of section 4.9
above).
Note that if the breaker is closed, it will trip.
Do not reclose the breaker until current is adjusted to
the desired value.
5.
Release
CALIB and GROUND TEST switches.
6.
Reset Trip Unit by pressing the “trip reset” pushbutton
on the Trip Unit.
7.
Close the breaker.
8.
Turn
TIMER “ON”. If TIMER does not read zero, push
manual
RESET (Timer) button.
9.
Push
RESET button.
10. While holding
GROUND TEST momentary switch in the
down position, push the
TEST button. Timer will give
an approximate reading of the delay.
11. Remove the Zone Interlock Shorting Plug, and repeat
the test. Time delay should read minimal.
