Quantam III dc drive field troublshoot

Is this motor critical to your operation? If so, order a spare, install it when it gets there and then send the old one for a look see at the OEM who built it.

Hello Chy2007

Could you give some details re:

1. Motor make, model, serial#
2. Motor normal voltage and current, as applied to the field winding
3. Motor normal voltage and current, as applied to the armature winding
   
4. Field controller: Make, Model, serial #

You state: "the motor,s field was gnd- to the motor case", do you mean the field winding was broken down = shorted to the Motor casing/Chassis or frame?

If so, was it caused by rodents, ants, water or other?

It's quite difficult to analyse a fault condition, from thousands of miles away, without the necessary facts, every bit helps.

If you are getting that motor field windings re-wound, I would be doing a very careful test of that Field winding Controller, which I am assuming is an electronic Controller, thus will probably have been damaged.

It always pays to keep a good spare of those Controller parts, cost is very small for good spares, when measured against the machinery being out of commission..

Kind Regards, appreciate your reply with........

500v arm, and 300 fieldv, thanks for the reply all info i donot have on hand Normally with this drive trouble with the armature has occured and the result is a shorted scr with a few 450amp fuses Ac power is filtered on main

Your motor field probably failed first, This will clear your field supply fuses, (FS1-2) It may or may not have damaged the field reg board and power cube. If you can power up drive (no motor connected) and fuses do not clear, your power cube is not shorted.

Next step would be to prove field reg board is working when motor is connected. I do not know the Quantum drive specifically. Basically if you power up drive and have output volts close to 300V it is probably OK.

You need to confirm that your drive is properly set up to safely control the motor. You should not be burning up motors if the drive is set up properly. You should confirm the current limits and overload settings. Also confirm that the motor field volts are at nameplate.

Add cooling blower to motor, and if your motor sits idle confirm your motor field has an "economy" or "reduced output" setting to prevent overheating when not rotating.

There are many possibilities, but it sounds like you are over working the motor, or do not have adequate motor cooling.

Thanks for the reply Mevel123 when the drive powered back up the field voltage was high around 600v I think after start-up it will regulate to 300 I believe this was the case another time when we lost a scr or 2 spare motor is around 30,000 so i have ben told there won"t be a spare. thanks for your feedback ang sugestions

600V is very high. Please note that SCR's are used in the armature circuit, as well as in some field supplies. They fail due to over current or over heating. Most drives of your size require a blower on the scr assembly- It is important to have adequate cooling on the scr's as well as the motor. With power off you should confirm the fins on the heat sinks are not clogged with dust. Also confirm your drive's power module fan is working.

You need to confirm that the motor field volts are correct with motor connected. It sounds like your model is a current regulating device. This means without motor connected it will go to full DC volts. With a cold field the volts will be less than rated, and after heating up (the motor field) the output volts should settle at rated. Please note that even 50 extra volts on a 300V field is enough to shorten the life of the motor, and you need to confirm the volts after motor field is hot. Good luck

DC Field are very highly inductive devices, and extremely high inductive overvoltages= L di/dt inductive voltages are developed during switching On , OFF and other normal operations. All DC field windings need to be fitted with permanently connected discargew resistances. These are Voltage dependent resistances VDRs and should have thermal ratings to suit the size of application.Even spark gaps can be fitted in certain installations.In absence of a VDR the Dc field windings can develop interturn shorts .

Subodh Kumar

You are correct, however his DC drive's field regulator has (or should have) similar protection, already built in. Also if the induced voltage caused the input fuses to clear, it would have to of shorted the power cube first, by exceeding it's rated back voltage.
This did not happen. What you say is important if he has been disconnecting the motor field (via switch) with power on, but I am not sure this was the case.