Chester Champion mill 3 phase questions

[martianParticipant @martian]

 

I recently bought a used Chester Champion milling machine of the type pictured below.
I seems that it was originally supplied with a 3-phase motor and Eurotherm drives inverter, power feed and cabinet from Chester.
It was advertised as motor not working and I was expecting to replace it. After some investigation I have found that there is no voltage coming from the inverter, so maybe the motor does work.

Before I buy a VFD how can I test if the motor works?

The data plate on the motor is unreadable so I don’t know exactly what I will need, but the old inverter supplied 0.55/0.75kW 3-phase. Can you recommend a suitable replacement?

Thanks in advance
Martin

[noel shelleyParticipant @noelshelley55608]

How you test it depends on what test gear you have  ? Checking the resistance of the 3 coils and if you can get your hands on an insulation tester (megger )then test the insulation. Is there an unpleasant smell of burnt insulation when you open the terminal box ? It will I expect be wired delta, change to star and try the motor on proper 3Ph or on a converter (transwave or motorun ) also 415V. If your near me I can help. Noel.

[Julie AnnParticipant @julieann]

There are many parameters and VFD inputs that need to set correctly before a VFD will output a waveform. Just because nothing is measured it doesn’t mean the VFD is broken. How you measure the output of the VFD is also important. The output is a PWM signal so if you stick a cheap meter across the outputs it will likely read about zero. Ideally an oscilloscope and a high voltage differential probe are required to measure the output of a VFD running from the mains.

Julie

[FulmenParticipant @fulmen]

If the motor measures OK you can try it on single phase. It won’t self start but with a little assistance it should spin up and run fine, albeit at low power. A better approach would be to wire it in steinmetz delta using a run capacitor:

https://electronics.stackexchange.com/questions/424068/3-phase-motor-running-on-single-phase-using-steinmetz-delta-connection

[Les Jones 1Participant @lesjones1]

Some years ago I was asked to try to test a VFD.  At the time I did not have a three phase  motor so I connected three mains voltage filament lamps (Wired in delta configuration.) to the VFD output. It showed that there was an output between the three phases. I also found that if the frequency (Speed control ) was turned down very low you see the brightness of the lamps changing in a rotating pattern.

Les.

[john fletcher 1Participant @johnfletcher1]

Regarding the motor, an insulation test using a 500volt DC supply, a Megger, or alternative make should be done. Connect one lead to a clean part of the motor frame, the earth, the other lead of the tester, connect it to each terminal inside the connection block, better get your friendly electrician to do it for you. Next, using an ohm meter, a DIY one is OK here, measure the resistance of each winding, they should be the same or near about. That sounds a lot, but 5 minutes, and the motor is checked, and half way there. Regarding the inverter output, in the past have done the same as Les above, and got similar result, now got a small motor. I find the inverter programming confusing, so much jargon.  John

[martianParticipant @martian]

Thanks for your replies. I have done some more investigation and have managed to run the motor connected to single phase with a capacitor.

On the Eurotherm drives 582 inverter there are 5 pots and ten switches that can be set as per the manual. I don’t see anything that would prevent an output.

 

When power is connected only the DC link capacitor LED is illuminated, the other three are off.

[Julie AnnParticipant @julieann]

If I’ve read that correctly LED1 to LED3 are off? If LED1 is off that implies the VFD is not getting power (or the LED is phut), which is pretty fundamental. I’d trace the incoming supply as far as I could; at least to the terminals on the VFD.

Julie

[SillyOldDufferModerator @sillyoldduffer]

Before jumping in at the deep end, assuming the motor is toast and reprogramming the VFD etc, does this machine have safety interlocks?  Look for wires leading to switches on moveable safety screens and doors – these are often arranged to stop the machine if the operator does something unexpected.    There might be an interlock on the perspex spindle screen.  These are often removed leaving the switch in the safe position, and the switch might have been moved since.  I see the mill has a powered traverse; this usually means two interlock switches arranged to stop the motor winding the table off the machine!  Quite often interlocks are arranged in series, so opening any one of them stops play. Not usual for interlock switches to vibrate loose and rotate rather than switch  as expected.  Make sure they are firmly in position.    All interlocks have to be closed, so check them all.

I recommend debugging from the input end, not back from the motor.  A multimeter is needed, and a circuit diagram is very helpful, plus the VFD manual.

Anyway, is mains reaching the VFD?  If not:

• check fuses, including inside the control box and the VFD cabinet
• The NVR often doubles as an emergency stop: make sure it’s been reset to go.
• check the No Volt Release Switch.  Fairly common for these to fail.  Sometimes the machine will work if the switch is held down manually.   If that happens replace the NVR.

If the VFD has mains power:

• look for loose wires: vibration can loosen terminal screws (likely) and might break crimped/soldered connections (unlikely).
• check for damaged insulation, usually where wires go through a hole or a clamp.
• speed control pots wear out or fill with dirt. (likely)  If the pot fails open circuit the VFD won’t power the motor.  A multimeter should show twirling the speed control varies the voltage control it applies to the VFD.   Probably between 0 and 5vdc.  If the voltage doesn’t vary, fit a new pot, not difficult.
• might be a contactor in the circuit. If so check it for loose wires, burnt out coil or bad contacts

Check all three output wires from the VFD to the motor are firmly connected at both ends.   Very bad things can happen one is loose – it can puncture insulation inside the motor and/or destroy the VFD’s output transistors.   Or, with luck, the VFD is clever enough to detect the fault and refuses to start until the wires are all present and correct.

Do you know the history?   Be good to know if the motor ever emitted magic smoke, or if anyone tried to reprogram the VFD, or has been at the wiring and switches before.   Or maybe used a megger on the motor whilst the VFD was still connected, that being a good way of killing electronics!   If it stopped working after a move, then the fault is probably loose wire simple.  If it failed during a heavy session, then either the VFD or the motor could be cooked, or both.

Les describes the light-bulb method of testing a VFD so try that.  If the bulbs work, then replace the motor. Shouldn’t be difficult – power is known and I;’d bet the farm on it being 230v delta, not 400v.  They have standard mountings, so measure them and compare with a catalogue – MachineMart might do.

If the VFD is deceased, might be worth resetting it (manual required), otherwise replace with a new one.   Not too difficult on a simple machine because most cheap VFDs come with ready to go factory defaults and a basis wiring diagram – not necessary to re-program them.

Advice as for eating an elephant – one mouthful at a time.   Step through logically until something wrong is found, and don’t be afraid to ask again.   Photographs are very helpful.

 

[DiogenesParticipant @diogenes]

I think checking the interlocks is a pretty good shout, if it was supplied to that spec’ by Chester from new, it’ll have been a bl pretty expensive option for a hobbyist, and maybe more likely to be ex-industrial/institutional..

[martianParticipant @martian]

Thanks for all your ideas.

There are no interlocks. The power feed has a separate tranformer that supplies 110v and it works correctly.

The spindle motor (the problem) is on a separate plug. With power on, I get voltage at the inverter input (L1 & L2) and the DC brake connections (+ & -).
LED1 2 and 3 are Not illuminated (the three circle below the pots). The DC link charge indicacator does illuminate.

I have a copy of the manual, it can be found at the link below.
https://www.manualslib.com/manual/1380912/Eurotherm-582.html

I’ll have another look tomorrow but I’m not too confident poking around inside with a multimeter.

Martin

[Nicholas FarrParticipant @nicholasfarr14254]

Hi, this Champion model didn’t have any interlocks, and they seemed to have withdrawn them in 2008/9, as they were not in their 2009 catalogue. The picture that Martin has posted above, is from their 2003 catalogue, and the specs are just the same as my one that I bought in 1997, to the last catalogue it was in, about 2008, the only real difference is mine is green, whereas they are white with the blue cross table by 2002. They were never advertised in their catalogues being fitted with a 3 phase motor and inverter, although they did sell both 3 phase motors and inverters in a different section, so they may have fitted them on request, at a higher price. the machine stand/oil tray were optional anyway.

Regards Nick.

[martianParticipant @martian]

Thanks for all your replies and advice.

The problem turned out to be the old inverter. I got a replacement of amazon, connected it up and it’s working.
Just need to make sense of the instructions now.

 

Thanks
Martin

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