New Laminations Testing for a Large Industrial Generator Stator

Project Description

NEW PRODUCT DEVELOPMENT
MULTIPLE PRODUCTS
MULTIPLE TESTS
Large corporation needs USA Contract Industrial Laboratory for testing a set of new laminations for a large industrial generator stator. They are thin sheets of metal, about .020 thick, with a thin primary insulative coating of a few microns, and a thicker varnish secondary insulative coating. Overall dimension of each is roughly 12.6 x 30.2.

The types of tests we are looking for are as follows:

1. Interlaminar resistance test
Two segments are used to measure the resistance between them. Stack the two segments on each other and put under a pressure of 1.5 MPa +- 0.1 MPa. Segments shall be insulated from the press. Voltage is applied on a raised corner of each segment from which varnish has been removed. Therefore only 2 layers of varnish are tested. The average interlaminar resistance over the segment surface is measured with a ohmmeter.

Minimum interlaminar resistance criteria for the interlaminar resistance test:
10 000 Ohm.cm2 on at least 90% of samples
1 000 Ohm.cm2 on the 10% remaining

2. Franklin test
Surface insulation resistivity as defined by ASTMA717/A717M.

3. Thickness measurement
Measure the segment insulation thickness on both sides, including the thickness remaining where we have the conveyers marks and scratches. Provide a sketch showing the different thicknesses found, the average, maximum and minimum. The lab shall verify that we still have a fine layer of insulation where we have the conveyer's marks.

4. Varnish curing
Verify varnish curing by rubbing a rag saturated with denatured alcohol (for water based second coating). The varnish shall not be removed after 20 rubbings.

5. Adherence inspection
Varnish adherence shall be tested according to Standard Test Methods for Measuring Adhesion by tape test ASTM D 3359 with acceptance criteria classification 4B.