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oper ation, has been set in co-ordination with the P2 potentiometer at
the factory and sealed.
Potentiometer
P2
milliseconds)
pickup
character is tic;
milliseconds)
tend
than
4. 16 milliseconds
the
character is tic.
increase the pickup time delay.
millisecond
(50
Turning the P3 potentiometer clockwise will increase the dropout time
delay.
The test circuit
state pickup time setting.
test circuit of
Figur e 31. ) A dual tr ace oscilloscope should be used with channel "A"
connected to test point "AIN" on the IT card and channel "B" on test
point "OUT" on the IT card.
"CIN" on IT card to "OV" test point on PS card.
the
pickup
time
tur ning
P3
counterclockwise
cycle.
Reduce "VT" until the relay picks up and the output
B)
should go positive 4. 16 milliseconds (50 hertz
after the input
checked, P3 should then be turned clockwise until the output (channel
B)
pr oduces a continuous positive signal.
clockwise for one additional turn.
As a final check on the accuracy of the 4. 16 milliseconds,
hertz - 5. 0 milliseconds)
compared with the desir ed characteristic.
To
check
pr ocedure should be used:
(a)
Remove the CL card
(b) Connect the test circuit of Figure 26
(c) With
normally closed contact.
the
positive 5. 5 milliseconds (50 hertz
millisecond) after the Channel One trace steps positive.
Overcurrent Super vision Tests
6 .
There
are
potentiometers
sensitivity of the overcurr ent supervision signal for each phase pair
as shown in table XVI.
The
test
circuit
super v1s1on
signal
recommended procedure for setting sensitivity is as follows:
a)
Make connections for phase pair AB and adjust current IT to
the
desir ed
load
curr ent
shifter for a phase angle meter reading at 85° .
Potentiometer Pl must not be readjusted.
is
set
for
time.
times longer that 4. 16 milliseconds
to
nar row
(50 hertz
Turning
her tz
6. 0
of
Figure
(The same r esults will be obtained if the
Figure 24 is used
delay,
the
dr opout
so
(channel A)
goes positive.
the mho character istic may be rechecked and
the
tr ansient
oscilloscope
on
for
setting
is
shown
value
of
and
minimum
GEK-49861
a
4. 16
millisecond
The
4. 16
millisecond
the
characteristic
- 5. 0 milliseconds)
the
P2
potentiometer
Potentiometer P3 is set for a five
milliseconds)
31 may
be used to check the steady
in place of
Connect unused inputs "AIN",
time
delay
that
the
output
After the pickup time is
P3 should then be turned
pickup
time
setting,
trigger
The
on
positive
Channel Two trace should step
-
the
SP
car d
sensitivity
in
Figure
24
current
super vision
fault
current) .
2 3
(50
hertz
(50
hertz
(50 hertz
and
times
tend
to widen
clockwise
dropout
time
the
test circuit of
"BIN",
In order to observe
must
be
r educed
resets
each
5. 0 milliseconds)
-
the
following
slope,
open
6. 6 milliseconds)
for
adjustment
of
the
overcurr ent
(or
Figure
31) .
(between
Set
the
5. 0
- 5. 0
shorter
will
delay.
or
by
half
(channel
(50
the
(±0. 1
of
the
The
maximum
phase
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