TY P E S I RP, I R C AND I R D
1 .
The upper bearing screw shoul d be screwed
down until there is approximately
.0 25
clearance be
tween it and the top of the shaft bearing. The upper
pin bearing shoul d then be securely locked in position
with the lock nut.
2.
Contact gap adjustment for the directional
unit is made with the moving contact in the reset
position, i . e. , against the right side of the bridge.
Advanc e the right hand stationary contact until the
contacts just clo se. Then advance the stationary
contact an additional one-half turn.
Now move in the left-hand stationary contact until
it just touches the moving contact. Then back off the
stationary contact
3/4
of one turn for a contact gap
of
. 0 20 "
to
. 0 24".
The cl amp holding the stationary
contact housing need not be loo sened for the adjust
ment since the clamp utilizes a spring-typ e a0tion in
holding the stationary contact in po sition.
3.
Insert tap screw of overcurrent unit in highest
tap. The sensitivity adjustment is made by varying
the tension of the spiral spring attached to the mov
ing element assembly, The spring is adjusted by plac
ing a screwdriver or similar tool into one of the
notches located on the periphery of the spring ad
juster and rotating it. The spring adjuster is located
on the underside of the bridge and is held in place
by a spring type clamp that doe s not have to be
loosened prior to making the necessary adjustments.
The spring is to be adjusted such that the con
tacts will clo se as indicated by a neon lamp in the
contact circuit when energized with the required
current and voltage as shown in Table
1.
This tabl e
indicates that the spring can be adjusted when the
phase angle relationship between the operating cir
cuit and the polarizing circuit is at the maximum
torque angle or when the circuit relationship has the
operating and polarizing circuits in phase.
4.
The magnetic plugs are used to reverse any
unwanted spurious torques that may be present when
the relay is energized on current
or voltage
alone.
The reversing of the spurious torques is accom
plished by using the adjusting plugs in the following
manner:
a)
Voltage circuit terminal s on the voltage polar
ized relays (IRP and IRD voltage polarized unit) are
short-circuited.
b) The polarizing c ircuits of the current polar
ized relays (IRC and IRD current polarized unit) are
open-circuited.
Upon completion of either •a" or ''b" current is
applied to the operating circuit terminals as per
26
Table
2.
Plug adjustment i s then made per Table
2
such
that the spurious torques are reversed. The plugs are
held in position by upp er and lower plug clips, These
clips nee d not be disturbed in any manner when mak
ing the necessary adjustment.
The m agnetic plug adjustment may be utilized to
po sitively close the contacts on current alone. This
may be desired on some installations in order to in
sure that the relay will always trip the break er on
zero potential .
Time Overcurrent Unit (CO)
1.
Contacts - The index mark on 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
"0"
mark by approximately
. 0 20".
The placement of
the various time dial positions in line with the index
mark will give operating times as shown on the re
spective time-current curves.
2)
Minimum
Current - The adjustment of
the spring tension in setting the minimum trip current
value of the relay is most conveniently made with the
damping magnet removed.
With the time dial set on
"0 " ,
wind up the spiral
spring by means of the spring adjuster until approxi
mately
6-3/4
convolutions show.
Set the relay on the minimum tap setting, the
time dial to position
6.
With the auxiliary switch (CS- 1) contacts blocked
closed, adjust the control spring tension so that the
moving contact will leave the backstop at tap value
current
+ 1 . 0%
and will return to the backstop at tap
value current
- 1 . 0%.
3)
Time Curve Calibration - Install the perma
nent magnet.
Apply the indicated current per Tabl e
3
for perma
nent magnet adj ustment ( e . g. IRP-8,
2
time s tap value)
and measure the operating time. Adjust the permanent
magnet keeper until the operating time corresponds
to the value of Table
3.
Apply the indicated current per Table
3
for the
electromagnet plug adjustment ( e. g. IRP-8,
20
times
tap value) and measure the operating time . Adjust the
proper plug until the operating time corresponds to
the value in Table
3.
( Withdrawing the left hand plug,
front view increases the operating time and withdraw
ing the right hand plug , front view, decreases the
time.) In adjusting the plugs, one plug should be
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