MTB_Hardtail
Member
We have 4 Inbound Carton Conveyors (same design) in our warehouse. 3 have been running for years with minimal issues. All have a Gapper Bed run by a 1HP 460V motor (1.7 FLA). VFDs are Powerflex 40, with 150 ohm Dynamic Brake Resistors. Overload current is set to 2.1A (125% of FLA)
Recently, #4 has been getting frequent JAMs, and has been faulting. PF40 Fault Queue shows 4, 5, 4 - Undervoltage and Overvoltage. Also getting occasional Current Overload. VFD failed and we replaced it. Same symptoms. Replaced the motor. Same symptoms.
Meggered the motor (500V), got 200+ Megohms per phase. Lifted the motor leads at the VFD, and meggered there. Similar readings.
PF40 HMI in current mode shows total motor current ranging from 2 Amps up to 4 Amps, with some excursions up to 4.3 Amps, followed by a fault.
Here is the interesting part: At the main panel, 100 ft away, we used a current coil ammeter, and got a reading on each of the 3 phases: 1.4A - 0.8A - 2.2A - So clearly, the VFD is giving us good Amp readings.
Question is, what could be the cause of such an extreme spread of current per phase? Especially given the VFD and motor were replaced with new? TIA - Jim
Recently, #4 has been getting frequent JAMs, and has been faulting. PF40 Fault Queue shows 4, 5, 4 - Undervoltage and Overvoltage. Also getting occasional Current Overload. VFD failed and we replaced it. Same symptoms. Replaced the motor. Same symptoms.
Meggered the motor (500V), got 200+ Megohms per phase. Lifted the motor leads at the VFD, and meggered there. Similar readings.
PF40 HMI in current mode shows total motor current ranging from 2 Amps up to 4 Amps, with some excursions up to 4.3 Amps, followed by a fault.
Here is the interesting part: At the main panel, 100 ft away, we used a current coil ammeter, and got a reading on each of the 3 phases: 1.4A - 0.8A - 2.2A - So clearly, the VFD is giving us good Amp readings.
Question is, what could be the cause of such an extreme spread of current per phase? Especially given the VFD and motor were replaced with new? TIA - Jim