1. Check if Motor Controller’s LEDs are ON.
• Please check the LED’s present on the Motor Controllers to determine if the unit is powered:
2. If no LEDs on, complete a visual inspection of the motor controller for damage:
• Visually inspect a physical damage on the Motor Controllers hardware
• Inspect the Motor controller cover for any burned spot or fumes mark
• Inspect Power harness and 3 phase wiring for any burned marks/spot in cause of short circuit
3. If no damage, verify wires on U, V, and W are properly secure.
• Please make sure to check/verify if the 3 phase line voltage wires terminated at the U, V and W wires are secured/connected properly
4. Verify voltage between U-V, V-W and U-W.
• Voltage measured (line to line) should fall between the NEMA rated specifications:
5. Check Jumper settings for J96 - J5122.
• See 6.4 Motor Controller Jumper Settings to determine the correct settings for P04/P04W and P05
6. Verify wires are on the supply side of the contactor (Line Side).
• Make sure the wires powering the SMC motor controller are on the supply side or the line side of the contactor, so that it gets uninterrupted power all the time
Note: Generally, RTUs turn the motor ON and OFF through the motor contactor based on an input received from the thermostat. The Motor Controller control logic, even though connected on supply/line side and powered ON, always keeps the motor idle. The Motor Controller only allows the motor to run when input from a thermostat is received so as to save energy.
Note: An illustration of Contactor:
7. Verify that no fuses or overload have been tripped/blown on the high power 3-phase powering the Motor controller.
• Please check the fuses or overload, during a short circuit/miswiring or it might have blown or tripped
8. Check for shorts or grounding issues.
• Check for any shorts or exposed wires. Often times a wire’s plastic jacket is striped during install which may cause unwanted shorts
9. Verify power at unit source (Disconnect).
• Please verify the power at the unit’s main disconnect and make sure it is not being disabled by the Buildings electrical room (if applicable)
Note: Only for illustration, model/part may vary on site
10. Is the disconnect making a proper connection. Replace if needed.
• Occasionally, a faulty safety switch may also cause tripping. Most of the time, broken or worn out safety switches will not trip or break circuit
• Check if they are working, and if they get stuck or don’t trip, replace them
• Verify that the blades of the disconnect are not stuck, broken, burnt or bent
11. Verify that the breaker has not been tripped. Reset if needed.
• Check if any other breaker on the upstream 3 phase line has been tripped/faulted and reset it if needed/required
12. Replace the damaged/faulty Motor controller with the spare, if available.