When replacing the coil, first disconnect the power supply, loosen the coil fixing screw, pull out the old coil, and insert the new coil (note that the voltage code must match).
The DC coil has polarity (+/-), and should not be wired in reverse.
5.3 Auxiliary contacts and timers
Snap on auxiliary contact modules can be used for top or side installation. Up to 2 modules can be installed (each module containing 1NO+1NC or 2NO/2NC).
Solid state timers (connection delay, disconnection delay) can also be mounted on coil terminals without additional wiring.
5.4 Reset Mode Settings
Default manual reset for bimetallic overload (requires pressing the blue reset button). It can be changed to automatic reset by modifying the code (note security risks).
External Reset is a standard configuration (Type 12 casing), and the reset lever extends from the casing. Internal Reset requires specifying the modification code R5.
Short circuit fault: same as the fuse part.

Chapter 6 Common Troubleshooting Guide
6.1 Motor cannot start, contactor does not engage
Possible causes and troubleshooting steps:
Missing or insufficient coil voltage: Use a multimeter to measure the terminal voltage of the coil. Compare the coil code (e.g. A=120V ± 10%). Check if the secondary fuse of the control transformer is blown.
Overload relay tripped: Observe whether the overload reset button pops up (bimetallic) or the LED status of C440 (red flashing indicates a fault). Before pressing the reset button, it is necessary to confirm that the motor is not overheated.
Control circuit wiring error: For models with CPT, check if the primary and secondary wiring of the transformer meets the selected voltage. For forward and reverse control, check if the interlock contacts are stuck.
Emergency stop or safety door lock circuit disconnection: The door interlock of the combination starter (if any) will disconnect the control circuit when the door is opened.
6.2 Contactor engages but motor buzzes and rotates slowly
Possible reasons:
Phase loss: Check if there is an open circuit in one phase of the fuse, circuit breaker, or wiring terminal. C440 solid-state overload will detect phase loss and delay tripping, but the contactor may have already been engaged.
Severe erosion or poor contact of contactor contacts: Disconnect the power supply and check the surface of the main contacts. If the contact pits are too deep or the silver dots are worn to a thickness of less than 1mm, the contactor or contact kit needs to be replaced.
Load mechanical jamming: Disconnect the motor coupling and conduct a no-load test.
6.3 Frequent tripping of overload relay
Bimetallic overload:
Heater selection too small: Check the motor FLA and the rated current of the heater. The heater should be selected at 100%~110% of the motor FLA.
Excessive ambient temperature: Although bimetallic materials have undergone environmental compensation, they still need to be corrected if they exceed the range of -10~40 ℃. The heater should be increased by one step every time it exceeds 10 ℃.
Frequent start stop: The motor starting current (usually 6 times FLA) will cause the heater to accumulate heat. If the start stop cycle is shorter than the cooling time, a larger heater or Class 30 solid-state overload should be used instead.
C440 solid-state overload:
Check if the setting current knob is aligned with the motor FLA (± 1% repeatability).
Check the trip level settings: Class 10 is suitable for light load starting, Class 20 is used for heavy load, and Class 30 is used for high inertia load. Setting too low can cause false jumps.
View fault records: Read the reason for the last trip (overload, phase loss, phase imbalance, grounding fault) through the communication interface. If it is phase imbalance, check whether the three-phase voltage is balanced (allowable difference ≤ 2%).
Ground fault protection (R64 only) misoperation: Check the insulation resistance of the motor and cable, as well as the set value of the ground fault current (adjustable).
6.4 Combination starter fuse frequently blows
Short circuit fault: Check for motor insulation and cable damage. Measure the relative ground and phase to phase resistance with a megohmmeter.
The rated value of the fuse is too low: Refer to the NEMA size selection table to ensure that the correct grade of dual element fuse is used (for example, a 60A fuse clip should be used for size 2, but the rated current of the fuse itself needs to be selected according to the motor FLA × 1.25~1.5 times).
Phase loss operation: After one phase fuse is blown, the increase in current in the other two phases can also cause the fuse to melt. At this point, the cause of the missing phase should be investigated first.
6.5 Unexpected tripping of circuit breaker
Instantaneous trip setting value too high or too low: HMCP's thermal magnetic release is set according to the motor FLA for long delay, and the instantaneous setting value is usually 13 times FLA (used for motor startup). If the trip occurs during startup, the instantaneous value can be appropriately increased (not exceeding 17 times).
Short circuit fault: same as the fuse part.
6.6 Control transformer overheating or smoking