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Servomotor temperature warning

Created by: leq1890 at: 1/15/2013 3:35 PM (7 Replies)

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1/15/2013 3:35 PM	Rate (0)
leq1890 Posts: 24 Rating: (0)	Hello, From some time we have problem with exceesed temperature on oneof our motor (motion control, servo). Torque (k241)is about 40%, OutPutAmps (k242) is about 30%. What we check: - Current is symetricall for all phases (measured with clamp) - All the mechanical devices (gearbox, process settings) were checked and are ok. - Servo is brand new - exchanged because of this problem. - SBM card was exchanged (it happen on another motor that sbm was cheating) External measurment confim high temperature Exceesed means: up to 120. To run, we blow motor with compressed air. Thanks for any advice
leq1890 Posts: 24 Rating: (0)
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1/17/2013 7:47 PM	Rate (0)
DenisMor Posts: 344 Rating: (50)	The motor is designed in such a way as to dissipate heat generated by torque generating current. As long as constant current (or RMS equivalent for variable load cycle operation) is below motor rated value, then the motor will produce less heat then it can dissipate. The following factors can have an effect: - Ambient temperature - Torque generating current above MOTOR rated values Is 40% torque, 30% current are relative to the rated value of the drive or the motor? What is the absolute value of torque and current produced by the drive relative to motor rated values? - Tuning If the motor is tuned "too hot" there may be oscillations present in the current loop resulting in excessive RMS current to the motor.
DenisMor Posts: 344 Rating: (50)
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1/18/2013 10:59 AM	Rate (0)
leq1890 Posts: 24 Rating: (0)	Hello, thanks for reply Ambient temp.is stable - other motors works in the same area without problems. Torque - K241= r007 = % refered to reference torque p354=14Nm (motor: 1FK7103-5AF71: Mn=14) Currnet - K242 = r004 = A (about 30% on trace), motor: 1FK7103-5AF71: In=12 (measured with clamps I=4A)
leq1890 Posts: 24 Rating: (0)
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1/18/2013 2:32 PM	Rate (0)
DenisMor Posts: 344 Rating: (50)	Does the current trace look stable, no oscillations?
DenisMor Posts: 344 Rating: (50)
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1/18/2013 3:33 PM	Rate (0)
leq1890 Posts: 24 Rating: (0)	I have attached trace For me it is quite stable Attachment trace.zip (446 Downloads)
leq1890 Posts: 24 Rating: (0)
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1/18/2013 4:33 PM	Rate (0)
DenisMor Posts: 344 Rating: (50)	Current trace does look stable. I would change encoder and power cables then. It's a long shot, but could be a bad temperature connection or loose power connection. As far as analyzing temperature, what was the temperature reading on the motor outer casing vs what the drive is measuring? There will be a difference, because temp sensor is in the motor winding. I would compare this difference to the motor that is running ok. Is there some natural air circulation around the motor? If the motor is enclosed in a box, for example, that would impede it's cooling ability. Other then that, the only thing would be left is to replace the power section of the drive in case it's a problem with the firing circuit (also not very likely).
DenisMor Posts: 344 Rating: (50)
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1/23/2013 11:58 AM	Rate (0)
leq1890 Posts: 24 Rating: (0)	Tomorrow we will exchange drive unit and see what will happen. Pyrometer: 84 C drive: 98 C Thank you
leq1890 Posts: 24 Rating: (0)
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5/21/2020 1:39 AM	Rate (0)
Sabarikrishnan Member Joined: 12/20/2019 Last visit: 10/16/2024 Posts: 3 Rating: (0)	Hi I am also facing same problem. One of our siemens servo motor is taking high current and torque. Current is oscillating between 0.8A to 7.1A depending on the speed and load. Also torque is getting oscillating between 20% to 100% sometimes which in turns lead to overtemp alarm and stops the motor. recently we replaced its resolver since old one got faulty.

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