bonny Posted July 29, 2008 Report Share Posted July 29, 2008 what are heating time constant & cooling time constant of induction motors. Link to comment Share on other sites More sharing options...
marke Posted July 29, 2008 Report Share Posted July 29, 2008 Hello bonny This varies considerably between motors as is reflected by the maximum Locked Rotor Time of motors. The maximum LR time for some motors can be as low as 5 - 10 seconds, and others as high as 40 - 50 seconds. To accommodate this variation, most good protection relays have a setting that reflects this value. The cooling time constant is likewise very variable and is dependent on whether the motor is running or not. While it is running, there is additional heat input, and additional cooling compared to a stationary motor. Best regards, Mark. Mark Empson | administratorSkype Contact = markempson | phone +64 274 363 067LMPForum | Power Factor | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | Pressure Transducers | Smart Relay | GSM Control | Mark Empson Website | AuCom | Soft Starters Link to comment Share on other sites More sharing options...
SCIM Posted August 14, 2008 Report Share Posted August 14, 2008 From what I know, the cooling time constant is the time required for the motor to cool down to ambient temperature from hot. This information is not critical to motor protection but maybe required as a input to the motor protection module you are using. This cooling time constant can be obtained from your motor manufacturer. It can be something like 60-120mins depending on the design. SCIM Link to comment Share on other sites More sharing options...
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