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Hardinge HLV-H blowing low voltage fuse

MattS1985

Plastic
Joined
Jul 31, 2020
Hi all,

I have lurked on this forum for many years... And the wealth of information is truly astounding. I have run into a problem with our shops HLV-H that I hope I can get pointed in the right direction with.

The lathe is a Hardinge HLV-H wired for 460v 3ph and powered by our shops 480v 3ph service.

I used the lathe on a Friday and it worked fine, but when I tried to use it on Monday it was completely dead. Over that weekend we did have some fairly decent thunderstorms in the area.

I checked all of the fuses and one of the low voltage fuses was blown. I installed a new fuse and the machine ran for about 15 seconds and blew the new fuse. I checked the ground connection and did a general once over of the mass of wiring (which just looks like wire spaghetti to me) and tried another fuse. Same result except this time I smelled electrical burning.

I did some basic continuity checks and found that the line side of the fuse socket in question has continuity to ground. The load side does not. The fuse socket's load side goes up to the on and off switches and then down to several relays or contactors (I don't know what they are to be honest.)

The Line side of the socket is fed directly from the "X2" (wire is also marked X2) position on the transformer. The transformer indicates that should be 110V output. I put the multimeter across the X2 output lug and a lug right next to it which is wired to ground and there was continuity / 1.2 Ohms resistance.

I'm no electrician but it seems to me like a hot leg from the transformer should not have continuity to ground?

Also a few of the relays/contactors have some burnt spots which may just be from use and age? I really don't know.

I am not opposed to calling someone in to the shop to get this problem sorted but I really don't know who to call... Anyone know what type of electrician does that work?

Thanks for any help or tips!

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I assume by lv you mean the 110v control voltage rather than the 50v lamp supply.

Check the fuse holder, i have seen these arc to the chassis (especially if damp)

Check the wires for chaffing where they pass through the cabinet

Trace the wire from the fuse , measuring the resistance to ground at each point, look for lowest/lower resistance and keep tracking till the resistance increases.

Bill
 
Yes it is the 110v line/fuse that is fed from the transformer in the lower left of the cabinet. I will try to check resistance on the wires and look closer for any damaged wires tommorow when I am back in the shop.

Thanks for the reply and pointers.
 
It is not uncommen to have one line of the transformer connected to ground
If you have the machine under power but furhtermore nothing switched on and in this situation the fuse holds you can assume the transformer is not the cullprit
If you have a electrical diagram any electrical skilled person should be able to solve the matter

Peter
 
John, yes I did get it figured out. I was close to calling a repairman out but took another crack at it and just started taking things apart.

The problem was the gasket for the carriage feed controls was leaking and cutting oil, way oil, etc. had made it's way inside and I believe compromised one of the wires that was touching the oil in the bottom as the wire sheathing was half gone and just fell apart when touched. Pulled the whole mechanism out so the wire was not contacting anything and the machine runs as normal.

It is temporarily electrical taped and I made a new gasket and cleaned out the compartment. I've got some new wire coming that I will run to the controls and probably install a junction box to tie everything together down in the collet cabinet where that wire goes up to the carriage controls.
 








 
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