Please help if anyone can. I must first state that I do not have any sort of vast electronic knowledge. I am a plant manager looking for answers. If your replies are too technical I will be assisted by my maintenance personnel.
I work for a book printer and we have a large fast web press with a 56 kw motor. We had trouble with our Eurotherm drive and had the back up drive installed. That back up was not up to par either so I ordered 2 Siemens Simoreg DC Master Drives (6RA7075-6FV62-0-2). The Eurotherm was out of date and we could only have it rebuilt so I chose to go new. We installed the new drive but had several hours of down time due to parameter settings that were slow coming from Siemens.
Once installed we were off and running. About one month later we started experiencing pre-set speed variation on start up. The press can crawl and run up to 1200 feet per minute. The pre-set speed on start up can be 600 fpm but the press would race to 950 fpm. We called the press manufacturer and they suggested some things to check but we found nothing (power supplies, reference voltage, current). After a couple of months of this speed control problem we started getting motor overheat errors. At times it was so bad the press would slow down and stop when we were running long runs at top speed. The motor is suppose to operate near 40 c and we checked it but it was only 43 c at most. The motor was well maintained, brushes always changed, armature looked good, etc. We even made sure and cleaned off the fan blades and blew out all dust.
The end result was that the manufacturer came in and installed that 2nd Siemens back up drive I purchased. Their claim was that the motor was suspect and could have harmed the drive. They felt there was an issue with the winding's insulation. My question here is that if we have never had a problem with the motor before how do I ascertain if the drive caused the motor to fail or visa versa. A classic, "What came first . . . the chicken or the egg." If I have Siemen fix the drive I will never find out. I feel that since these speed and heat issues did not transpire till the drive was installed that the drive caused the motor's problems therefore adversely affecting the condition of the insulation over a 6 month time span.
Any ideas out there to check in order to prove either way?
[email protected]
I work for a book printer and we have a large fast web press with a 56 kw motor. We had trouble with our Eurotherm drive and had the back up drive installed. That back up was not up to par either so I ordered 2 Siemens Simoreg DC Master Drives (6RA7075-6FV62-0-2). The Eurotherm was out of date and we could only have it rebuilt so I chose to go new. We installed the new drive but had several hours of down time due to parameter settings that were slow coming from Siemens.
Once installed we were off and running. About one month later we started experiencing pre-set speed variation on start up. The press can crawl and run up to 1200 feet per minute. The pre-set speed on start up can be 600 fpm but the press would race to 950 fpm. We called the press manufacturer and they suggested some things to check but we found nothing (power supplies, reference voltage, current). After a couple of months of this speed control problem we started getting motor overheat errors. At times it was so bad the press would slow down and stop when we were running long runs at top speed. The motor is suppose to operate near 40 c and we checked it but it was only 43 c at most. The motor was well maintained, brushes always changed, armature looked good, etc. We even made sure and cleaned off the fan blades and blew out all dust.
The end result was that the manufacturer came in and installed that 2nd Siemens back up drive I purchased. Their claim was that the motor was suspect and could have harmed the drive. They felt there was an issue with the winding's insulation. My question here is that if we have never had a problem with the motor before how do I ascertain if the drive caused the motor to fail or visa versa. A classic, "What came first . . . the chicken or the egg." If I have Siemen fix the drive I will never find out. I feel that since these speed and heat issues did not transpire till the drive was installed that the drive caused the motor's problems therefore adversely affecting the condition of the insulation over a 6 month time span.
Any ideas out there to check in order to prove either way?
[email protected]
Last edited: