*
TYPE IRQ R ELAY
VOLTAGE
o20 VOlT
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184A599
Fig. 12. Test Diagram for Checking Maximum Torque Angle
ancl Min imum Voltage for Contact Closure of the
D irectional Unit.
The above quantities are determined as
follows : V A2 = Neg. Sequence Voltage
V A2 = .!._ (VAN + az VBN + a VcN)
3
V A2 = __!_
<3_
V AB -
..!:_
a2 V AB - ..!:_ a V AB)
3 3
3
3
v
= V AB
(�
_
.!._
az
_
.!._
a)
A2
3 3
3
VAB
V A2 =
for V AB = 0 . 57 volts
VA2
=
0 . 1 0 volts
IA2 =
..!:_
(IA + az IB + ale)
3
IA2 = .!._
(0
+ az I - al)
3
IA2
for I = 6 .93 amps .
IA2 = 4
should pick up within
±
10% of the above input volt
age to the relay.
3.
Spurious Torque - With the relay connected
in the test diagram as above, remove the input volt
age and connect terminais 14, 15, and 16 together.
Remove the phase-angle meter.
With 80 amperes
single-phase current applied, there should be no
spurious closing torque.
T i m e O ve r c u rrent U n i t (C O )
1 . Contacts - The index mark o n the movement
frame will coincide with the
"0"
mark on the time
dial when the stationary contact has moved through
approximately one-half of its normal deflection. There
fore, with the stationary contact resting against the
backstop, the index mark is offset to the right of the
1 0
"0"
mark approximately . 020" . The placement o f
the various time dial po�itions i n line with the index
mark will give operating times as shown on the re
spective time-current curves.
2.
Trip Current - Set the time dial to
position 6 with the auxiliary switch (C&- 1) contacts
blocked closed, alternately apply tap value current
plus 3o/c and tap value current minus
3o/c.
The moving
contact should leave the backstop at tap value cur
rent plus
3%
and should return
to
the backstop at
tap value current minus 3%.
3.
Time Curve - Table 1 shows the time curve
calibration points for the various types of relays.
With the time dial set to the indicated position, apply
the current specified by Table 1 ( e . g. for the IRQ- 2 ,
3
and 20 times tap value current). And measure the
operating time of the relay.
The operating times
should equal those of Table 1 plus or minus 5 p ercent.
For type IRQ- 1 1 relay only, the 1..30 times tap
value operating time from the number 6 time dial
position in 54.9 ±5o/c seconds. It is important that the
1.30 times tap value current be maintained accurate
ly. The maintaining of this current accurately i s ne
cessary because of the steepness of the slope of the
time-current characteristic (Fig. 2 1) . .
A 1o/c variation
in the 1 . 30 times tap value current (including mea
suring instrument deviation) will change the nominal
operating time by approximately 4o/c.
I n sta n t a n eo u s O ve r c urrent U n i t
(I)
1. Contact Gap - The gap between the stationary
and moving contacts with the relay in the de-ener
gized position should be approximately . 0 20 " .
2 . Minimum Trip Current - The normally-closed
contact of the directional unit should be blocked open
when checking the pick-up of the overcurrent unit.
The pick-up of the overcurrent unit can be check
ed by inserting the tap screw in the desired tap hole
and applying rated tap value current. The contact,
should close within ± 5o/c of the tap value current.
I n d i
ca
t i n g C o n t a c t o r S w i t c h e s ( I C S / 1 a n d ( I C S/ T )
A) Close the contacts of the CO and p ass suf
ficient d. c. current through the trip circuit to close
the contacts of (ICS/T). This value of current should
not be greater than the p articular (ICS/T) tap setting
being used. The operation indicator target should
drop freely, bringing the letter "T" into view.
B) Close the contacts of the instantaneous over
current unit
(I)
and the directional
(D).
Pass suf
ficient d. c. current through the trip circuit to close
the contacts of (ICS/I). This value of current should
not be greater than the particular (ICS/I) tap setting
being used.
The operation indicator target should
drop freely, bringing the letter "I" into view.
C) The contact gap should be approximately
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