The $64,000 question is. Do you ever use it?
Phase rotation meter ?
- Thread starter Evans Electric
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They use DC for the inter country links to reduce polarisation losses, if you reverse the cable polarity then you have to re-polarise the capacitance every half cycle, this uses energy and is thus a loss.
With DC long distance HV transmission the lines are polarised once and that's it.
AC is used for the UK grid so that it can be transformed up and down to minimise the AC losses, and due to the way that it is distributed a lot, i.e. overhead singles with air as the insulator there is little in the way of polarisation losses.
You do get polarisation losses in underground cables, and that is a cost that has to be borne.
With DC long distance HV transmission the lines are polarised once and that's it.
AC is used for the UK grid so that it can be transformed up and down to minimise the AC losses, and due to the way that it is distributed a lot, i.e. overhead singles with air as the insulator there is little in the way of polarisation losses.
You do get polarisation losses in underground cables, and that is a cost that has to be borne.
My MFT has phase rotation and I also have a separate phase rotation meter.
It's normally the installation guys on CNC machinery that get hung up about it, especially the cheap ones, because they don't fit hose rotation detection to them, so it has to be right, or it screws them up.
The better drives either don't care, or they tell you that it's wrong.
With AC permag servo's it doesn't really matter as they take the 3ph and make DC out of it to chop it up again as a PWM waveform, and the motor rotation is dependent upon which order they fire the output stages anyway, so that's down to the drive control.
I spent several months building CNC machines, what a pain in the arse. The DWP wanted me back in work, eventually they decided I was disabled and gave up.
Very interesting thanks ...something I knew nothing about except that the links exist.
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The image I can see has three Croc clips on it.....strangely Red Black and Green, but Croc clips nonetheless
you dont usually have anywhere to attach the croc clips. mine (martindale) came with 1x croc clip & 2x probes (no idea why), that soon got changed to 3x probes
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i was thinking more down the lines of......could be handy to clip to a motor ( before connecting) to check rotation
Even though you've proved rotation, I'd still always try an run the actual motor to be connected without a load attached. Someone could've messed up at the factory or rewind shop. It does happen.
Yeah it has been done!
If the load won’t suffer any damage and there’s two of us then a quick contactor dab with a driver and a cable tie up it's fan is normally enough!
The non contact phase rotation tester which you sit on the motor & connect to the phases should give you the correct phasing though.
even better when you plug in a TP machine that has 2 motors but 1 is wired wrong...
I’m always wary of rewinds, wrong rotation, reversed windings, even the motor winding leads not connected.
A quick flick to check rotation is not time wasted.
A quick flick to check rotation is not time wasted.
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