PAYESH SANAT KAVIR Condition Monitoring Solutions
The following is an excerpt from William T. Thomson’s book.
It demands more than that and an engineer who intends to apply MCSA should obtain the following competencies
The ability to correctly understand the principles of operation of a 3-phase induction motor during normal operation and to correctly apply the basic equations which are required for MCSA testing.
An understanding of the basic construction of large SCIMs.
An understanding of the implications of DOL starts, the torque versus speed curves of the SCIM and its mechanical loads and how to calculate, for example, the run-up time of the motor when driving a mechanical load such as a compressor or pump.
In which MCSA detected broken rotor bars, were due to the following
Too many sequential (DOL) starts causing inherent high starting currents,outwith the motor’s design capabilities, Richard Nailen [1.51, 1.52], for example, when the end user does not abide by the original manufacturer’s (OEM’s) specification for the time delays between sequential starts.
Incorrect matching of the motor’s torque–speed curve to the torque–speed curve of the load, so that there is insufficient accelerating torque to cope with all the starting conditions, to which the motor may be subjected by the end user.