Power Feed failure

[Dave CParticipant @davec87625]

Hi Guys

I am very hopeful somebody out there can offer me some advice regarding my power feed. The feed is on my Bridgeport mill. The mill is 3 phase and I run it through a Jaguar Inverter. The power feed side runs on 110V I power the mill through the inverter and everything still works fine Spindle etc.

I was using the power feed on a job taking medium cuts and all was fine with no issues. I then went to proceed with another cut and nothing ! I wasn't using the power feed to the Y axis but this also now has no power.

Opening the Mains power box shows the ( MCB ) ? has tripped. I can reset this and it remains set but still no power. Looking at the contactor to the left hand side it appears seized . The other contractors allow movement of the part circled in the photo ie spring back when pushed ( Not whilst plugged in I may add ) I don't mess in there under power. I can also see and hear the other contactor move when the on switch of the mill is pressed. The power feed contactor does nothing and as I say appears solid. Is it likely that the contactor is the problem or am I just being very hopeful.

I have found the same contactor on line or at least one looking identical with the same code K2-A9 A10. Am I to assume if this if required it will be the same voltage etc. Or will there be variants of this. I am NO electrician.

There are no in line fuses that I can see. I have an old identical power feed which was removed as it has a damaged gear inside but still worked under power. This has no power either and so I am assuming it isn't a power feed unit fault, Also both axis now no longer work.

Very long winded I know but any help or advice would be very much appreciated.

Edited By Dave C on 10/10/2021 20:10:32

Edited By Dave C on 10/10/2021 20:11:12

Edited By Dave C on 10/10/2021 20:12:19

[Dave CParticipant @davec87625]

[not done it yetParticipant @notdoneityet]

You may well be on the right track but some voltage measurements with a good meter would confirm your suspicion.

[Mike PooleParticipant @mikepoole82104]

You will need to check the coil voltage of the contactor as many options are fitted. DC versions can have a flywheel diode fitted, sometimes it is a separate module as it is not required in all applications. The code on the top of the contactor probably isn’t the full part number, this is usually on a label on the side. The coil voltage may be located on the coil or on part of the coil assembly. A close examination of the contactor should reveal all the details you need for a replacement. Most manufacturers will make an equivalent device but be sure you match the normally open and normally closed contact arrangement.

Mike

[Dave CParticipant @davec87625]

Thanks very much for the help.

I will take the contactor off and get the details from it. For the prise of a new one I will swap it over and hopefully be back in action.

Dave

[Clive FosterParticipant @clivefoster55965]

As Mike says these contactors frequently have lots of options.

Generally, especially industrial rated types, they are built up by mixing'n matching from a wide selection of coils, contact sets and other components to suit various duties. Its likely that the number you see is actually the contact set identifier and the full specification will be on a label stuck to the side. Which do fall off. I've played hunt the label in the bottom of a cabinet a time or three!

For a job like this its usually not too difficult to figure out what goes where and what switches to what so an equivalent can be found. From the looks and application I'd say it's a pretty standard device.

Clive

[noel shelleyParticipant @noelshelley55608]

Do you have a wiring diagram ? This may be a big help in tracing whats what. What model of Bridgeport is it ? Is the fault in the contactor ? has the wiring to the contactor failed, is it the coil, is it the switch to the coil , is it the contacts? IF its the coil you may be able to buy just the coil. Has the 110v transformer gone ? IMO are a common maker so a replacement should be simple matter but make sure you get the right coil voltage – the coil may be supplied seperately. Good luck. Noel

[duncan webster 1Participant @duncanwebster1]

Is the contactor between the motor and the inverter? If so I'm not sure this is a good idea, no doubt others more qualified will advise.

[Robert Atkinson 2Participant @robertatkinson2]

If you are using the VFD to change the motor speed, rather than just single to 3 phase at a fixed 50 or 60Hz you will have problems. The VFD output voltage varies with the frequency (speed). This is to maintain the correct current through the motor. The issu is transformer ratios are fixed regardless of frequency. This means that the contactor coils may be overloaded depending on the exact design and settings.
Many VFD designs also generate high voltage spikes during operation. These can cause insulation breakdown in the contactor coils. These spikes and the waveforms enerated by the VFD also mean you cannot use a common multimeter to measure voltages.
To get accuracy you need a "True RMS" meter accurate to several kilohertz. To safety and to prevent damage to the meter it should be PROPERLY rated as CATIII 100V minimum.

You should re-wire the machine so the control circuits and power traverse are powered from a supply derived from the fixed frequency mains. The VFD shoud power the motor only.

Robert G8RPI.

[Dave CParticipant @davec87625]

OK then

Firstly my apologies for the delay in replying, Work and life got in the way.

The Vfd Is just to convert to single phase.

Speeds are altered with the manual vari speed control.

The transformer still appears to be working fine.

The mill is wired as it came from the dealer and has not been altered by myself. It has however worked perfectly for the last five years or so. The spindle still works fine it is just the 2 off power feed units which now show as having no power ie no green light on the units. These are both powered by a separate 110V transformer.

I have tonight removed the contactor and to my untrained eye the coil appears to be damaged / burnt. Luckily all the information on the unit is still readable if I need to replace with similar from somewhere / somehow. I wouldn't know where to start looking.

I have added photos of the contactor and overall wiring which will hopefully make sense to somebody a lot smarter than me.

I don't have a wiring diagram.

Thankyou to all that have replied with advice and information, it is very gratefully received.

[Robert Atkinson 2Participant @robertatkinson2]

Hi,

I can't tell if the auxiliary contact is Normally Open (NO) or Normally Closed (NC). This is the green terminals at the end. Can you check with a meter?
If they are NO (same as main contacts) this one will do the job:

https://uk.farnell.com/imo-precision-controls/mc10n-s-10110ac/contactor-4kw-10a-110vac/dp/9940472

The coil failure may just be random or the VFD waveform may have been the last straw. Either way replace the contactor and either wait and see if it is OK. Cheking the voltage across the coil.would be a good precaution.
Personally I'd wire the 110V transformer directly to the mans bypasing the VFD. The transformer may have a suitable 240V winding.

Robert G8RPI.

Edited By Robert Atkinson 2 on 12/10/2021 21:08:48

[Mike PooleParticipant @mikepoole82104]

If you dismantle the contactor you may just need a new coil, you mentioned the contactor is jammed and this often happens when the coil overheats and the armature sticks in the coil bobbin that distorts with the heat. The contactor does look a bit past it’s best though so maybe a replacement would be best.

Mike

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