Hi. For a caged induction motor, what is the current at one end of the short circuit end ring i.e. is it the summation of all of the rotor bar currents?
What are the things or calculation you would consider to determine if your motor could operate under fault conditions (e.g line-to-line or earth fault)?
I am assuming that if a phase fault happen, you would get higher negative sequence current as a result of unbalance 3-phase motor. Therefore...
I have read some online references on this topic and the method of calculating the torque and current under short circuit, reconnecting and starting consist of loads of calculus and numerical methods. Is there an easier way to do it so that I could use Excel to display the numbers and plots? I...
Hi. I am a new starter with a company which manufactures water-filled motors. There was an incident on a 6kV motor 400kW 2960rpm motor driving a centrifugal pump. It was summarised that the impeller damaged to the extent of fully worn out. As a result, the rotor shaft became unstable and caused...
Very often during testing while the rotor is locked, reduced voltage is applied to the motor, and current measured.
1. Do you normally use the straight line rule to extrapolate the current to the rated voltage? If it is a curve, what is the relationship, and how do you normally do the...
Imagine you have a piece of long wire that consist of the copper conductor and insulation (EPR or XLP). There was a puncture on a small section of the wire. I have seen an engineer using a Meggar with one probe on the puncture area, and the other probe on the copper conductor to determine the...
I have tested two identical 6.6kV motor, water-filled and windings are XLPE-insulated. One passed, and one failed the test. This is a rare occurence. The failed test has a flashover at 5kV very close to the star point.
Historically, this motor had failed the test once before at the same...
Does the length of a cable has any effect on the insulation resistance?
When an insulation resistance value of a cable is given as 10 G-ohm.meter, does it mean for a 10m cable, the IR is 1Gohm?
Why are there different test voltage for an IR test? Will using a different level of test voltage...
Is the high voltage test and insulation resistance test applicable for a temperature probe (Pt100) which have a rating of 250V, 2 element x 3 core? The temperature detector is for measuring motor cavity water for a submersible motor.
How would you normally do these tests? At what test voltages...
Is the high voltage test and insulation resistance test applicable for a temperature probe (Pt100) which have a rating of 250V, 2 element x 3 core? The temperature detector is for measuring motor cavity water for a submersible motor.
How would you normally do these tests? At what test voltages...
I have a 1050kW 6600V 50Hz motor connected to a gen set for a centrifugal pump testing. The gen set supplier planned to use the frequency start to ramp up the motor to full speed, while varying the voltage accodingly to the speed of the generator. They suggested that the ramp up time would be...
