VFD PE leakage current - Page 1
Forum section: electronics / beginners

author: gaminn
author_rank: Frequent Contributor
timestamp: February 27, 2024, 08:13:42 pm
content: Hi,I bought Lenze E82EV751_4C Lenze 400V AC VFDhttps://inverterdrive.com/file/lenze-8200-technical-manualbut I'm unable to run it in my workshop as my 20mA residual-current circuit breaker (ground fault circuit interrupter) triggers everytime I turn the VFD on. I tested that with 75 VAC power supply, I get 20 mA leakage current via PE, so with 400 VAC power supply the leakage current is probably more than 100 mA. Is that normal or is my VFD damaged?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 27, 2024, 11:03:03 pm
content: The leakage could be from the motor. I actually always find some current in the ground wire for a VFD. So perhaps you should use another circuit breaker.

author: gaminn
author_rank: Frequent Contributor
timestamp: February 28, 2024, 10:27:02 am
content: There is currently no motor connected to the VFD.I realized that my main problem was that I intentionally connected 400V 3 phase VFD to 2 phase 230 V power supply - I just wanted to test the VFD and set some parameters to it. The VFD with 2 phase 230V connected to it shows under-voltage error but still it is possible to set parameters via its keypad.I experimented a little bit with voltage and number of phases connected to the VFD (L1, L2, L3 terminals). I didn't connect PE of the VFD to PE in my socket.230V 2phase: There is 112V/50Hz between PE of VFD and PE in my socket. Unable to measure current to PE as residual-current circuit breaker triggers immediatelly.400V 2 phases only: 33,5V/150Hz between PEs, 12 mA residual current through PE.400V all 3 phases: 22V/150Hz between PEs, 23 mA residual current via PE.Why 400V power supply shows 150Hz voltage between PEs and why is there much higher PE leakage current for 230V 2 phase power supply?

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 28, 2024, 10:45:33 am
content: Although I use a lot of the Lenze 8200 series, I always connect them to 400V 3 phase and with the motor. I did notice there was some current in the ground wire but otherwise everything worked fine. I never connect them to 230 or single phase power.

author: gaminn
author_rank: Frequent Contributor
timestamp: February 28, 2024, 10:58:20 am
content: Now I know that it is not a good idea to connect 3x400V VFD to 2x230V power supply.I'm just curious what happens inside the VFD that the PE residual current is so much higher at 230V.

author: BeBuLamar
author_rank: Super Contributor
timestamp: February 28, 2024, 05:37:05 pm
content: When you said 230V 2 phase is one of the phase at PE potential that is it's a neutral and the other is 230V to PE? Or both are 115V with respect to PE?

author: gaminn
author_rank: Frequent Contributor
timestamp: February 28, 2024, 06:21:23 pm
content: It is neutral and 230V to PE.

author: sicco
author_rank: Regular Contributor
timestamp: February 29, 2024, 02:46:44 pm
content: VFDs with those ratings typically have EMC filters. Capacitors from all 3 Vin pins to PE and chassis. That makes the RCD’s trip. Sometimes you can disable the EMC filter by removing a screw. At the expense of no longer filtering and thus facing RF interference / compliance issues.