I bought a Rexon bench grinder in December. I unpacked it and tested it briefly in the house and left it to one side until I had made a pedestal for it. Well, you know how it goes. I only got round to making the pedestal this week. So I bolted the grinder to the pedestal, plugged it in, switched it on and it barely started to move before it stopped. "Ah", I thought, "start-up current". Checked the garage consumer unit and went to reset the 16A breaker but it hadn't tripped. It took me a few seconds to think what else could have happened and then I looked at the main switch/RCD, which had tripped.
Anyway, I couldn't get it to run without tripping the RCD. I realised that my initial test on arrival was on a supply with no RCD (none on the house consumer unit). So to prove it wasn't a faulty RCD I took it back into the house, connected it through a plug-in RCD and switched it on. It ran for a second, then tripped. Eventually I found that I could get it going by running it up to speed without the RCD and then swapping quickly to the RCD. Even then, it would occasionally trip after running for a while at no-load speed.
Anyway, the point is that I spoke to the supplier and they first suggested that some motors take more than their rated "voltage" while they're starting up (this was a sales guy so I made allowances). When I pointed out that the problem was the RCD and not a circuit-breaker, he said he'd pass it to their technical guy. He wasn't available so the sales guy is now awaiting a response from Rexon.
I can't figure out how a correctly-functioning motor could cause this. It's an induction motor, as far as I can see. There's a starter cap in the base.
I also checked resistance between live, neutral, earth on the plug with the grinder's switch on. There was nothing suspect but I didn't expect it to be as simple as that since it has some dependence on startup.
Anyway, while I wait for a response, is there any likelihood that this device is operating as intended or (as I believe) is it likely to be faulty? I have a few other tools with this type of motor, like the bandsaw and 3hp compressor. Neither of these causes a problem on the RCD.
Anyway, I couldn't get it to run without tripping the RCD. I realised that my initial test on arrival was on a supply with no RCD (none on the house consumer unit). So to prove it wasn't a faulty RCD I took it back into the house, connected it through a plug-in RCD and switched it on. It ran for a second, then tripped. Eventually I found that I could get it going by running it up to speed without the RCD and then swapping quickly to the RCD. Even then, it would occasionally trip after running for a while at no-load speed.
Anyway, the point is that I spoke to the supplier and they first suggested that some motors take more than their rated "voltage" while they're starting up (this was a sales guy so I made allowances). When I pointed out that the problem was the RCD and not a circuit-breaker, he said he'd pass it to their technical guy. He wasn't available so the sales guy is now awaiting a response from Rexon.
I can't figure out how a correctly-functioning motor could cause this. It's an induction motor, as far as I can see. There's a starter cap in the base.
I also checked resistance between live, neutral, earth on the plug with the grinder's switch on. There was nothing suspect but I didn't expect it to be as simple as that since it has some dependence on startup.
Anyway, while I wait for a response, is there any likelihood that this device is operating as intended or (as I believe) is it likely to be faulty? I have a few other tools with this type of motor, like the bandsaw and 3hp compressor. Neither of these causes a problem on the RCD.
