Hi - Posting in the right discussion forum now:
I would like to know what tests should be performed in a repaired motor to assure the repair was done correctly and motor is running properly. Could you please list a set of tests to be performed/standards of reference. Thanks
Motor is:
2250 HP
50 Hz
3 phase
6 kV
330 RPM

Depends on what was repaired?

Isn't there a standard from IEE on what tests to do after motor overhaul/repair/rewinding?

Two widely available repair standards:

IEEE 1068 - Standard for repair of motors for the Petrochemical Industries.

EASA AR100 - Recommended Practice for the Repair of Rotating Electrical Apparatus - Available for free here:
http://www.easa.com/indus/ar100-2001.pdf#search=%22AR10...te%3Awww.easa.com%22

You can also ask your repair shop what tests they recommend.

ClaudioR

To ensure the motor was wound properly and the insulation is in a good condition a winding resistance test, Meg-ohm, PI, DC Step voltage test, and surge test should be performed at a minimum. I have attached a motor testing guide line for you to get an idea of what voltages should be applied to the motor and pass fail criteria. These tests really do not evaluate the stator laminations although I have heard of motor shops indicating a surge test can find lamination problems. The best test to evaluate the laminations is a core loss test. Another thing I would insist on is making sure that all motors are burnt out with a controlled burn out oven. This will ensure the motor laminations are not damaged during the process.

If the proper care in the motor repair process a motor can be repaired many times with no effect on the motor and if the proper materials are utilized the motor can be better than some new motors.

EASA is a great resource for all this information www.EASA.com and then go to Industry Information. They have a number of articles.

I hope this is of some help

JAG

Baker_Instrument_Off-line_Electric_Motor_Testing_Guidelines.doc (56 Kb, 36 downloads)

ClaudioR:

We just completed setting up these practices through one of my large automotive clients and steel clients. The objective is to have the most effective testing program as well as working closely with the motor repair vendor.

The two standards outlined by ElectricPete are a great place to start. First of all, the AR-100 was developed by the Electrical Apparatus Service Association (EASA) as a standard that covers motor repair excellence that any EASA shop should be able to follow. The IEEE 1068 was developed as a general repair specification that also outlines the appropriate IEEE test standards through the repair process. There used to be an excellent standards collection for rotating machinery (all in one book!), but that has been discontinued.

In either case, part of ensuring that you are getting a good repair from your repair shop is to work with them to ensure that all of the appropriate quality control steps are being followed and that they provide a report showing a complete set of all the tests and their results. That can be used as a baseline to ensure that the repair meets minimum standards (or any other standard that you agree to). You will also want to communicate that you are performing your own inspections on the equipment.

At each of my automotive and steel clients, we have set up inspection requirements for rotating machines that are quite stringent, yet are normally applied by the shipping and receiving departments. Then we have a required repaired/new equipment commissioning best practice.

The receiving departments perform a visual inspection on the equipment and ensure that everything has been returned that was sent out while also looking for cracked, broken or visibly defective parts. They then perform MCA tests, which take about 5 minutes, to evaluate the condition of the equipment electrically and install an 'electrically tested good' tag on the motor. If the motor is going into storage as a spare, then certain requirements are met to ensure that the condition of the equipment is maintained.

One of my real world experiences with the type of tests that Jag outlined is that if something does not pass the tests, many motor repair shops will claim that the company's motor inspector damaged the windings.

Once motors are installed, then an installed commissioning set of inspections and tests are performed. This ensures that the machine was installed properly. Insulation and visual inspections are performed (insulation to ground 'megger' tests) and the equipment is energized. Once energized, then ESA and vibration tests are performed.

We set criticality and size limits on the amount of commissioning and inspection tests that are performed such that you are not expending unnecessary resources while getting an optimum return. The programs have been extremely successful.

Howard

MotorDoc, could you kindly elaborate on what criticality and size limits do you use to ensure optimum commissioning and inpection tests? Have you written an articel or paper on it?

Thanks for the valuable information Folks. I believe I have enough info to start discussing with the repair shop the repair scope and tests protocols.

Regards
ClaudioR