4.4 START TIMER
Before performing any
start
tinier
teS.ts
discharge the memory
by
connecting
a
jumper
across
emergency
restart terminals 3 and 4 for 5 seconds. With the
voltage compensation switch off (Section 3.10) turn on the injection set so that a
balanced overload
is
immediately applied to the relay. This will simulate motor
starting causing both the overload and start lights to come on. The relay should
trip after the time set on the start timer. On start time and overload tests, there will
be a
30
minute lockout before resetting is possible if the injected signal
is
removed
as
soon
as
the relay has tripped. Delaying removal of the applied signal
after a
trip
allows
the relay
to
continue charging
and
may
result
in
a
much
longer
lockout period.
If the voltage compensation switch
is
left on the actual start time will differ from
the dial setting
as
explained
in
Section 3.10.
4.5 UNBALANCE
Unbalance detection is simulated
by
injecting a different current
in
each of
the 3 phases and noting the unbalance control setting at which the unbalance
light comes on. The scale value at this point should correspond to the degree of
unbalance simulated according to the formulae of Section 3.3. For example,
using a 5 amp
CT
relay with the full load control set at
60%
and the unbalance
control at
50%
inject phase currents of 2 amps, 2 amps and 1 amp. Dial the
unbalance control back until the unbalance light comes on. The value at this
point should be approximately
22%
as
determined from:
10n-0avl
·
~~-x100
0FLC
=11-1.661
0.6X5
X
100
=
22%
Unbalance
After about 5 seconds of continuous unbalance the relay should trip.
4.6 UNDERCURRENT
Set the full load control to
50%
and the undercurrent control to
60%.
When the
injected current falls below
60%
of
the
maximum load setting the auxiliary relay
will be activated if this feature has been enabled (Section 3.10). Thus for a 5 amp
CT
relay, when the input current falls below
60%
of (0.5x5
amps)=1.5
amps the
auxiliary relay will
be
activated with the undercurrent light on. Increasing the
current clears the condition automatically.
4.7
GROUND
FAULT
Connect
a single phase through the window of the ground fault current trans-
former
as
shown
in
Figure
4-l
Note
the
required trip current and time from the
yellow product specification card and Section 3.11. Increase the current from
the test set until the relay trips with the ground fault light on. It should require a
current equal to the setting value
+o.
-25%
to cause a ground fault trip. If the
ground fault alarm
is
enabled, the auxiliary relay should activate at a current
approximately one half this value.
32
Courtesy of NationalSwitchgear.com
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