Factory acceptance test 11kV motor 1

[freetown]

Hi all,

We are scheduled to perform a factory acceptance test at a manufacturer for a new slip-ring induction 11kV (3000Kw, 180A, 990 rpm) motor. I am particularly interested in gaining more insight into the following tests:

Withstand voltage tests: According to the IEC standard, the test voltage is defined as 1000 V plus twice the rated voltage, subject to agreement. Does this imply that the customer assumes full responsibility upon agreeing to conduct this test, leaving the manufacturer without liability? The phrase "subject to agreement" is unclear for me in this context.

Rotor stator voltage ratio measurement UR/US : After some research, I couldn’t find the purpose of this test and the acceptable value criteria.

 

[wcaseyharman]

Can’t speak for motors but in the generator space failing a hi-pot during a factory or field acceptance test is on the manufacturer.
In my experience the test value of the withstand test is often discussed and agreed on - usually 2E+1 for the final acceptance but there are intermediate tests during manufacture that can often go higher. We asked and agreed for the coils on a generator to be tested at 2E+3 at the factory before installing - which was fine since when we tested some sample coils to failure they failed at almost 4E.

 

[edison123]

2U+1 AC HV test is a requirement for new motors and rewound motors and the full responsibility lies with the OEM/rewinder.

Partly rewound machines and overhauled machines are AC HV tested at their appropriate values as per standard, but the risk is under the customer. As a rewinder, I advise and take the client's consent with the caveat we will not be responsible any winding failure during this AC HV test since the winding is not ours.

Open circuit test is another requirement to check the rotor induced voltage of the slipring motor, and it should match the nameplate rotor voltage since you will be responsible for the rotor side starter design to match the rotor voltage and current.

 

[Gr8blu]

Agree with Muthu. New windings get tested using an AC voltage at (2x rated volts + 1000) as a standard practice. Alternative conditions - including the use of a DC source - are also possible - but require user agreement/specification up front (meaning before the winding is designed/installed, not just before the test is performed).

Windings that have been "in service" - which includes those that have merely been sitting in storage for an extended period - can be tested at the user request. Typical value is roughly 60-75% of the "new winding" test value. This is called a "maintenance level" dielectric test. This is ALSO included in both the IEC and IEEE standards documentation.

Repair facilities will not take responsibility for testing a "used" winding at elevated conditions. The user must first specify the test as required, and between the two an appropriate test voltage is arrived at given the actual condition of the winding and insulation system(s).