CL4 VSLK click on down powering

[Deejay]

Afternoon all

A year or so after I bought my lathe, the speed controller failed. Record sent a courier to collect it the next day, repaired it and sent it back. All done FOC under warranty.

I had got into the habit of leaving the mains switched on at the plug after I stopped the lathe via the stop button. I think this burned out the track on the potentiometer, which was replaced.

When it came back, I ran a test, to see if I could find out the reason for the failure.

Switch on, press start the motor spins. Press the stop button the motor stops. If I then switch off the mains at the plug, after about ten seconds I hear a click, as if a relay held in by a charged capacitor has released.

I now disconnect at the socket at the end of a session.

Does anyone else's VSLK behave in this way?

Cheers

Dave

 

[CHJ]

Would not deem anything wrong with your delayed 'click' after removing power source, most invertors hold a significant high voltage charge for one reason or another after power interrupt, indeed you should never touch any invertor wiring for a few minutes after powering down for this very reason, giving time for the inbuilt safety circuits to bleed off the charge.

As far a switching off power at the socket when leaving the machine, no problem with that, indeed the particular invertor fitted to my lathe insists you remove the power feed after an overload shutdown fault (caused by a dramatic catch for instance) and wait for the 'discharge cycle' to complete before it will let you start up again.

 

[Stiggy]

That happens to my CL4 as well - it's normal.

 

[Deejay]

Thanks for the replies

Chas

The ten second delay only starts when you down power at the socket.

I would have thought that everything electrical would be disconnected by pressing the stop button and releasing the NVR switch. In my case it seems that part of the inverter wiring is fed from the supply side of the NVR. Can you suggest a reason why it might be wired that way?

If I wait half an hour before disconnecting the plug, I still have the ten seconds delay before the thing clicks.

Stiggy It may well be normal, but is it right? :lol:

I'll be interested to see if any other owners have the same feature.

Cheers

Dave

 

[Stiggy]

Good question - I don't know if it's right!

I like to unplug everything, or turn off power to the workshop via the consumer unit when I leave my workshop - for safety.

 

[CHJ]

......Chas

The ten second delay only starts when you down power at the socket.

I would have thought that everything electrical would be disconnected by pressing the stop button and releasing the NVR switch. In my case it seems that part of the inverter wiring is fed from the supply side of the NVR. Can you suggest a reason why it might be wired that way?

If I wait half an hour before disconnecting the plug, I still have the ten seconds delay before the thing clicks.

....

Are you sure your Stop switch is an electro/mechanical latched NVR, the simplified wiring diagram I've found for a CL4 shows mains permanently connected to the invertor and the start stop functions appear to be via the invertor circuitry, is yours by any chance the same?

 

[Sheptonphil]

On the Jet 3520b the inverter is the NVR, the switch on the headstock only depowers the motor, not the inverter. It also clicks several seconds after the wall switch is turned off. If the headstock switch is left and when turned off at the wall, it must be turned off and back on to start th lathe. Thus click is normal with inverter (three phase motor from 240v supply) powered lathes, it was the same for the Axi 1628vs.

Phil

 

[Paul Hannaby]

Perhaps you are assuming the stop/start buttons are a NVR switch when they are actually just control switches for the inverter? If the inverter is configured to be in the stop condition when power is first applied (so if there was an interruption to the power, it wouldn't restart when power returned), I guess you could argue there is no need for an NVR switch...

However, this does mean the inverter is on unless you turn it off at the socket and yes, it's common for inverters to take several seconds or longer to discharge.

 

[CHJ]

I personally am never happy to rely on an electronic circuit as a vital safety 'lock out'.
Even an electro/mechanical NVR switch can fail to operate mechanically due to dust etc.
Always at least switch off at source and better still disconnect (unplug) if working on the machine changing components (chucks etc.) or servicing.


I view this 'electronic' blocking of restart as a cost cutting exercise that saves a manufacturer fitting a separate mechanical break in the supply chain.

 

[Paul Hannaby]

The "electronic" blocking could effectively be the equivalent of an NVR switch on the inverter. That could be the clicking relay which is heard when de-energised.

 

[CHJ]

The "electronic" blocking could effectively be the equivalent of an NVR switch on the inverter. That could be the clicking relay which is heard when de-energised.

It may satisfy the requirement to prevent automatic restart after a power failure in terms of the law, but it's not unknown for electronic components to fail and I'd rather put my safety in the hands of a basic un-energised mechanically latched relay than a powered circuit feed holding something in or clamping an oscillator or Thyristor/Triac circuit .

Would certainly be interested in how such inverters satisfy the NVR requirement.

Where's Myfordman, he may have internals diagram for such.

 

[Deejay]

Morning all

I had another look at the lathe this morning. It looks like the NVR function is done within the 'black box' shown on Chas's diagram.

The start button doesn't lock in. Whatever is behind it, probably a non-locking make contact, sounds like it is operating a relay within the VSLK box. Similarily the stop button stops the motor while making a click, which is possibly the relay releasing.

When the potentiometer failed, I associated it with the mains being left on. Since then I have switched it off at the socket. With the mains off, it can't happen again. Interestingly, RP replaced the carbon tracked pot. with what appears to be a wire wound one.

Thanks again for the replies.

Cheers

Dave

 

[Paul Hannaby]

Chas,
I don't think the mechanically latched relays in an NVR switch are any more reliable than a similar relay arrangement in an inverter. In either case, it's possible for the switch contacts to fuse together so the output is permanently on. Neither type of control should be treated as adequate for isolating the machine for maintenance.

Dave,
It makes sense what you say about the wire wound pot. They have a higher current rating than the carbon track types so it sounds like Record discovered a design problem farther down the line and chose to retrofit a better component. Leaving the inverter powered up shouldn't have contributed to the failure.

 

[CHJ]

....... Neither type of control should be treated as adequate for isolating the machine for maintenance.

......

Fully concur with that, even a domestic style switched mains socket can fail so removing Plug from power socket or the Fusing devices from fixed wiring is a wise precaution before any in depth maintenance involving electrically powered equipment.

 

[andygc]

See my thread about reversing the CL4 which describes the control circuit.

reversing-the-record-cl4-t92686.html

 

[SVB]

indeed the particular invertor fitted to my lathe insists you remove the power feed after an overload shutdown fault (caused by a dramatic catch for instance) and wait for the 'discharge cycle' to complete before it will let you start up again.

I can't add to the electrik pixies debate but this caught my eye - care to expand Chas?!?!? What sort of catch do you need to wipe out an invertor? :shock:

 

[CHJ]

indeed the particular invertor fitted to my lathe insists you remove the power feed after an overload shutdown fault (caused by a dramatic catch for instance) and wait for the 'discharge cycle' to complete before it will let you start up again.

I can't add to the electrik pixies debate but this caught my eye - care to expand Chas?!?!? What sort of catch do you need to wipe out an invertor? :shock:

I have my invertor set to limit motor current very near full mechanical load limits, when I first had machine I took heavy cuts on a test piece to the point motor just objected, and set the current limit to a fraction above. (can't remember what it was now, it was 10 yrs ago.)

If I get a serious catch or fail to notice if the spindle lock has not cleared, the invertor just shuts down and spindle stops immediately. The latter case being the main occurrence.

Just one bad catch in 12 months or so is enough to make me glad it does it.

 

[SVB]

Ah, a very sensible and wise approach.

(I was hoping for a great story of daring-do and battle against uneven odds with good eventually defeating adversity, maybe next time!)

BRgds

Simon.

 

[mpcpba]

Sorry to pick up on an oldish thread- but in summary is there a chance that something will burn out in the control box if i leave my 6 month old CL4 plugged in after use? Quite new to turning and still juggling how the garage workshop will be set up so it would be good to know for sure as getting to the plug every night is not too easy just yet!

Ps I do tend to keep my Record Power bandsaw plugged in all the time I must admit and hope that is okay?

Cheers

 

[Deejay]

Afternoon Malcolm

If you switch it off at the socket or pull the plug, no harm will come to it.

Cheers

Dave