wadkin lathe motor

[NetBlindPaul]

^+1 to CHJ with regard to discharge times they can hold 800V d.c. (direct c(k)iller) voltage in the bus capacitors for several minutes after shut down. Not all bus voltages are this high, some are only 300V d.c.
There has to be capacitance on the d.c. bus within these units to allow for speed changes and other dymanic responses.

By the way, looking at the contacts on the IMO inverter drawing posted by CHJ, there are no switches shown, there are normally open contacts shown, however, there is no method of actuation shown.
This on advanced industrial machinery may well be via plc outputs.
Other means can be used.
I would use a contactor to switch these inputs, not a switch, ever.

The IMO unit is not my choice and I have quite a lot of experience of inverter type units from most of the major players.
Siemens, Control Techniques, Schneider, Bosch, Refu, IMO, and others whose names escape me now, too late on a Friday afternoon!
Given choice I would use, Bosch Rexroth, CT, Schneider, Siemens in that order as those are the drives I have the most experience with and have programmed up the most times, I also have some of the programming software, & interfaces thus it makes life easier!

 

[wallace]

Hi all, well I left this thread for one night and look what happened, Paul I have no problem with anybody giveing me advice on how best or how to procede in the safest way. I was shop steward and safety rep before I was made redundant last year, so I like to know everything before I attempt things. The chap I know is a very capable 'fitter' and has worked with industrial electrics for a long time. Jack I read your restoration from start to finish yesterday and was hugely impressed. I hope I can do half as good of a job. Most of this electrical talk is going over my head. I'm tempted to fit a converter and just use the belt adjustment on the lathe

 

[tool613]

Jack I read your restoration from start to finish yesterday and was hugely impressed. I hope I can do half as good of a job.

thanks Wallace. they are the best lathe in the world,and worth all the effort.

if you need any help just pm


jack

 

[OldWood]

Sorry to bump this post back up again, but I'm interested in the necessity of an NVR/MC/DOL upstream of an inverter when the box itself can be set up to cut out if there is a mains glitch. I've now reset my own one to do this (didn't think this through properly when I set it up :shock: ) and I've checked that the other ones I have an interest in are set properly.

If the box can do it and isolation exists in the form of a 13A FCU/SKt, is further NVR switch isolation necessary ? It is interesting to note that a Speed Genie package that I installed comes in a wall mounted box with all switching, lights, etc. and it doesn't include an NVR.

Rob

 

[loz]

Rather than "waiting" for capacitors to discharge, perhaps mention of the use of the Brinkley stick might be worthwhile? - Its what i used before entering high power transmitter cabinets.

Regs

Laurence

 

[CHJ]

Sorry to bump this post back up again, but I'm interested in the necessity of an NVR/MC/DOL upstream of an inverter when the box itself can be set up to cut out if there is a mains glitch. ...

Personally, having worked with electronic equipment for some years I would rather rely on a switch that physically breaks a circuit, be it an NVR or a momentarily latched relay that automatically drops out than ever I would trust a transistor/thyristor/triac circuit to prevent power passage.
Having said that I don't trust a standard switch either so I may be over cautious, they have been known to weld shut under fault conditions and always pull a plug out or remove fusing before working on anything.

 

[NetBlindPaul]

I can't comment as my opinions are those of someone professionally involved.



CHJ,
No switch should weld closed if it is correctly selected.







Else,

I don’t know what else I can suggest.
I feel that some of the inverter manuals have been incorrectly interpreted end of.
The NO contacts have been taken as a mechanical switch, where as if you study the data they are almost certainly an NVR contact.
However this is DIY stuff so I know nothing apparently.

 

[CHJ]

..they have been known to weld shut under fault conditions..

And

CHJ,
No switch should ...

Are still enough for me not to trust any switch without checking.

Would you put your hands into a garden shredder, or nearer home for a wood worker, a chip extractor fan to clear a blockage with just the wall socket mains switch turned off for safety?

I've seen single switches fail in Armament and Ordinance circuits where the switches themselves have cost more than most DIY kit.
Many hours are spent just checking that the relays in the circuits are where they should be and not stuck due to spring failure or welded contacts.

Most 'home' or 'DIY' switches rely on the function of a simple spring or an over centre rocking action and where that spring is the beryllium enhanced contact leaf itself, overheating can leave it vulnerable. (how many amps can a 13amp domestic socket switch be subjected to on motor start up ? !!)

Electronic switches (as found in converters) I trust even less as an isolating media.

And getting back to the original cause of these comments about converters and switching. I pointed out that a converter (or its associated wiring) may not be set up to fail safe 'ish', this indeed proved to be a fact in at least one instance, so as far as I'm concerned the comment served its purpose.

Professional expertise is invaluable for finite diagnosis of difficult fault occurences, but some basic practical checks and solutions can often save lives, body parts and a whole lot of unnecessary expense and frustration.