Home Forums General Discussion Technical Questions Tripping overload with phase converter

Installing a hydraulic package with Virginia controller - job has single phase coming in so we have a phase technologies solid state phase converter, motor is nidec 230v.... running up the motor is loud as hell, and after about 6-8 seconds my overload trips. Triple checked wiring of the motor with my Mfg and see no issues. When running up and measuring voltage between legs I have a drop on one set that goes down from 240 to 175 and another set goes down to 215. Mfg is at a loss and electrician isn’t much help. My knowledge of electrical and motors is not too advanced so I’m stuck. Not sure if this is a motor problem causing it or incoming power from the phase converter? Appreciate any help or suggestions

Is it running the right direction?

The motor should be inverter rated but that would most likely just affect longevity. I’ve never seen an inverter type phase converter on a hydro. Thyssen just uses capacitor start for single phase jobs. But the inverter on my mill runs the 3 phase motor beautifully. Lots of variables with inverters and single phase power though. What is the incoming voltage phase to phase? What is the model of the inverter?

so i spoke to a few techs on both the motor side and phase converter side. sitting idle i was seeing 240 leg to leg all around, as i ran up i had two drops to 175 and 215 which i thought may be part of the issue. Speaking to the Converter tech he said this is normal it seems because it looks like the motor is pulling too many amps and the phase converter is actually designed so that it drops voltage if greater than 130 amps are being pulled. The controller manufacturer is now having me rewire the Motor Overload relay so that the T3 leg to the motor essentially by passes the overload. Apparently they think the electronic overload is having issues because of the way the phase converter is providing the 3 phase power... or something along those lines. Doesn't make much sense to me, the motor is loud as all hell when running too but apparently they think rewiring this overload will correct that as well.

A static converter might need to be substantially oversized for the motor it's running. I ran into problems running my lathe and mill using a converter I made from scratch. I eventually bought an off-the-shelf rotary converter from Phase-a-matic. You might look at their web page for insight.

A buddy runs his lathe off a static converter that is apparently sized correctly, but his motor takes a long time to get up to speed. One more thing, if you're going to run computer equipment, you'll probably need to be oversized and then filter the output from the converter.

More updates - rewiring the overload did not change anything so now the controller manufacturer is sending a completely different type of overload to replace what is currently there.... they are thinking the current electronic overload is having issues with the 3 phase produced by the phase converter. So im currently awaiting a new overload....strange thing is i have the same set up on another new install i'm doing and did not have these issues....and when i say same set up i mean almost exactly the same. Same phase converter, same elevator controller and same motor, same overload in controller... makes me question the phase converter and how it is wired up at the job im having issues at (electrician there is not the greatest to put it lightly). will try to send an update when i change out that overload

another update for those interested - no change, phase converter tech now sending a new board for the phase converter. Looking to be an issue with the converter not the elevator.

Thanks for the update. Keep us posted.