Drives Service & Support > 1336F > Fault Finder

Fault Number: 09
Fault Display: Open Pot Fault
Fault Name: Open Pot Fault
Description: An external pot is connected and the common side of the pot is open..
Corrective Action: The drive will generate this fault when the voltage between pot leads is greater than 3.9 volts DC. When an external potentiometer is hooked up to the drive, and no analog I/O option cards are installed (LA2, 6, or 7), the potentiometer will most likely be wired to terminals 1, 2, and 4 on TB2. Terminal 1 is a +5 volt DC reference signal. The potentiometer wiper will be wired to terminal 2 (input 0), or could be wired to terminal 3 (input 1). The last of the three potentiometer wires will be connected to terminal 4, or signal common.

Remove the wires from terminals 1 and 4 on TB2. Perform a continuity test, from these two wires. Do not leave them hooked up to the drive, as an inaccurate reading will occur. You should read 10k ohms, which should be the resistance of your potentiometer.

If you read 10k ohms, a bad connection may have been the cause of the fault. Reattach the wires, and check for the fault to occur again. If it does not, then a bad connection was the cause. If the fault reoccurs, then the main control board should be replaced.

If you read infinite resistance, or an intermittant connection, then the wiring and potentiometer should be inspected.

If you read higher or lower than 10k ohms (~10% tolerance), then the wrong potentiometer size is being used. Install a 10k ohm potentiometer.

If you read 0 ohms, or close to 0 ohms, you have shorted wiring or faulty potentiometer.

This fault can be disabled by using parameter 150 (4-20mA Loss Select) by changing bit 0, 1, or 2 to a value of 0.