Conference Year
2021
Keywords
inverter, BLDC, PMAC, stator, compressor, force failure test, dielectric strength, reliability, product safety
Abstract
(PMAC) Electric motor is used at Variable Speed Refrigeration Compressors. Stator is the stationary part of a PMAC motor and stator wires directly carry the current, which energizes the motor and runs the refrigerator compressors. These wires are wound on stator stack which is made of electrical steel. The windings can be also close to other metal parts of the compressor. Stator stack is connected to compressor metal parts by metal screws. So, if a leakage current occurs through the stator stack, it is directly conveyed to compressor housing and then to refrigerator which can cause electric shock on the customer. That’s why, not only the quality but also the reliability of insulation between stator wires and metal parts is so critical. Standard dielectric strength tests are applied to both stators and compressors during production in order to check the insulation quality for product safety in the field. But it is not possible to detect the weakness and aging in this way. Most insulaton faults arise in time by repetitive voltage increase, thermal, mechanical, environmental and electrical stresses. This study explains the test which is carried out to detect potential electrical safety, leakage current and compressor failure problems which can occur on inverter stators in process of time. The development of Forced Failure Dielectric Test for the stators aims to uncover the insulation weakness which cannot be find out by Quality Tests and which can cause functional and safety problems in the field.