Electrical Drives Troubleshooting Tips

Electrical drives troubleshooting consist of the complete understanding of maintenance. This is one of the area most engineers are not compatible with. While a bad service is certainly a possibility. Electrical drives troubleshooting topic will let you understand this easily. There are several things you can do to insure you’re looking in the right place for the root cause of the problem.

Drive doesn’t run the motor

This is one of the questions we’re most frequently asked. While a bad drive is certainly a possibility, there are several things you can do to insure you’re looking in the right place for the root cause of the problem.

• Line power: Make sure the drive is actually receiving power. The best way to accomplish this is to measure the supply voltage as close as possible to the drive, ideally right at the power input terminals.

• Proper connection of motor: If the motor leads aren’t connected directly to the drive terminals, any device external to the output of the drive can be a potential suspect. Most DC motors have an armature resistance in the 10s of ohms or less. Measure the motor resistance right at the drive. If the measurement shows an open (high ohm value), the problem is not the drive. Check motor relays, plugs, connectors, conduit boxes, etc.

• Make sure the motor is receiving a signal: Measure the voltage at the drive’s output terminals. If there’s a voltage present, then the drive is telling the motor to rotate. If the motor is not moving, then there is something wrong in the motor wiring or with the motor itself.

• Control signal: Make sure the drive is actually receiving a command signal to make the motor run. If using a speed potentiometer, measure across the CCW terminal and the center terminal to see if there is a linear increase or decrease in the command signal as you vary the position of the potentiometer. If an external command signal is being provided, make sure it varies in the way you’d expect.

• Enable/Inhibit: Some applications may use inhibit or enable commands. Make sure the drive is not being commanded to not put out motor voltage. Most drives have Inhibit terminals and some also have Enable terminals.

• Trim pot adjustments: Some adjustments on the drive can cause motor voltage not to be present. A Current Limit pot when set too far CCW can cause the motor to stall as soon as it demands current.

• Input Voltage Selector Switches: While many drives have auto ranging power supplies, some drives may require you to setup the drive to accept either 115VAC or 230VAC.


Exceeding the drive’s current rating or ambient operating temperature can stress the drive to the point of failure.

Current Limitation should be in every drive as per specs, otherwise when overloaded (because of human factors, we are trying to push everything to the very/over the limits), some/all IGBT’s or whatever final power components we have will blow out because of overload/overcurrent…

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