41-101.3A
Type CKO Overcurrent Relay
20
7.0 TIME OVERCURRENT UNIT (CO)
a. 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. Therefore, with the station-
ary contact resting against the backstop, the index
mark is offset to the right of the "0" mark by approxi-
mately .020". The placement of the various time dial
positions in line with the index mark will give operat-
ing times as shown on the respective time current
curves.
b. Minimum Trip Current
The adjustment of the spring tension in setting the
minimum trip current value of the relay is most con-
veniently 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 approximately
6 3/4 convolutions show.
Set the relay on the minimum tap setting, the time
dial to position 6.
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%.
c. Time Curve Calibration
Install the permanent magnet. Apply the indicated
current per Table 1 for permanent magnet adjust-
ment (e.g., CKO-8, 2 times tap value) and measure
the operating time. Adjust the permanent magnet
keeper until the operating time corresponds to the
value of Table 1.
Apply the indicated current per Table 1 for the elec-
tromagnet plug adjustment (e.g., CKO-8, 20 times
tap value) and measure the operating time. Adjust
the proper plug until the operating time corresponds
to the value in Table 1. (Withdrawing the left hand
plug, front view increases the operating time and
withdrawing the right hand plug, front view, decreas-
es the time. In adjusting the plugs, one plug should
be screwed in completely and the other plug run in or
out until the proper operating time has been ob-
tained.
Recheck the permanent magnet adjustment. If the
operating time for this calibration point has changed,
readjust the permanent magnet and then recheck
the electromagnet plug adjustment.
7.1
Indicating Contactor Switches (ICS/I) AND
(ICS/T)
For proper contact adjustment, insert a .030" feeler
gauge between the core pin and the armature. Hold
the armature closed against the core pin and gauge
and adjust the stationary contacts such that they just
TABLE 1
TIME CURVE CALIBRATION DATA - 60 HERTZ
PERMANENT MAGNET ADJUSTMENT
ELECTROMAGNET PLUGS
TIME-
TIME
CURRENT
OPERATING
CURRENT
OPERATING
OVERCURRENT
DIAL
(MULTIPLES OF
TIME
MULTIPLES OF
TIME
UNIT TYPE
POSITION
TAP VALUE)
SECONDS
TAP VALUE)
SECONDS
2
6
3
0.57
20
0.22
5
6
2
37.80
10
14.30
6
6
2
2.46
20
1.19
7
6
2
4.27
20
1.11
8
6
2
13.35
20
1.11
9
6
2
8.87
20
0.65
11
6
2
11.27
20
0.24
Содержание CKO-5
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