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3 - INSTALLATION
Current Transformers
3.7 Current Transformers
3.7.1 CT Mounting
For starters larger than 124 amps, the CTs are shipped loose from the power stack and need to be mounted on the power wiring. Thread
the incoming lead through the CT with the polarity mark towards the line side. (The polarity marks may be a white or yellow dot, an “X”
on the side of the CT, or the white wire.) Each phase has its own CT. The CT must then be attached to the power wiring, at least three
inches from the power wire lugs, using two tie-wraps.
3.7.2 CT Polarity
The CT has a polarity that must be correct for the starter to correctly measure Watts, kW Hours, Power Factor, and for the Power and
TruTorque motor control functions to operate properly.
Each CT has a dot on one side of the flat surfaces. This dot, normally white in color, must be facing in the direction of the line.
CT1 must be on Line L1, CT2 must be on Line L2, CT3 must be on Line L3.
Socket size across flats Tightening torque
inches (mm) Pound-inches (N-m)
1/8 (3.2) 45 (5.1)
5/32 (4.0) 100 (11.3)
3/16 (4.8) 120 (13.6)
7/32 (5.6) 150 (16.9)
¼ (6.4) 200 (22.6)
5/16 (7.9) 275 (31.1)
3/8 (9.5) 275 (42.4)
½ (12.7) 500 (56.5)
9/16 (14.3) 600 (67.8)
z NOTE – For screws with multiple tightening means, the largest torque value associated with the conductor size
shall be marked. Slot length shall be measured at the bottom of the slot.
Table 16: Tightening Torque for Inside Hex Screws
FRONT VIEW SIDE VIEW DETAIL
MUST BE A 3" (MIN.)
SPACE BETWEEN CT
AND TOP OF LUG
CUSTOMER MUST FASTEN CT
TO POWER WIRE WITH TWO 1/4"
NYLON WRAPS TO PREVENT
MOVEMENT DURING RUNNING
Dot, or X,
White Wire
Figure 11: Typical CT Mounting, Input of Starter
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