The testing procedure for these tests are the same, but instead of applying a DC voltage, an AC signal is applied to provide better indication of the overall condition of the groundwall insulation. The dissipation factor and capacitance to ground test provide additional indication of the overall condition of the insulation. This test identifies any weaknesses in the groundwall insulation system. NEMA, IEC, IEEE, NFPA provide various tables and guidelines for the recommended test voltage and minimum insulation to ground values dependent on the motors supply voltage. Then measure the insulation resistance value of each lead to ground and verify the value exceeds the recommended minimum value for the motors supply voltage. If any value other than 0 displays, reconnect the test leads to ground and retest until a 0 reading is obtained.ģ) Remove one of the test leads from ground and connect to each of the motor leads. Measure the insulation resistance to ground (IRG).
![3phase motor winding diagram 3phase motor winding diagram](https://slideplayer.com/slide/13342733/80/images/7/Three+phase+AC-Single+layer+wave+winding-24+slot%2C+3phase%2C+4+pole+machine.jpg)
To test the condition of the ground wall insulation measurements are made from the winding leads T1, T2, T3 to ground.īest practices test the winding path to ground. This test provides a DC voltage to the motor winding and measures how much current flows through the insulation to ground:ġ) Test the motor de-energized by using a properly working voltmeter.Ģ) Place both instrument test leads to ground and verify a solid connection to ground of the instrument lead. This creates a safety issue since it provides a path for the supply voltage from the winding to extend to the frame or other exposed parts of the machine.
3PHASE MOTOR WINDING DIAGRAM HOW TO
How to Test Groundwall InsulationĪ ground fault or a short to ground occurs when the resistance value of the ground wall insulation decreases and allows the current to flow to ground or an exposed part of the machine. Knowing how to check your windings will allow your team to be proactive and take the appropriate action to prevent unwanted motor failure. Since most insulation failure occurs over time, MCA technology provides the measurements required to identify these small changes that determine the condition of the winding insulation system. The sudden failure of any part of the motor will cause loss of production, increased maintenance expense, loss, or damage to capital and possibly personal injury. These changes cannot be detected visually, or even with traditional electrical testing instruments like ohmmeters or megohmmeters.
![3phase motor winding diagram 3phase motor winding diagram](https://pengky.cn/zz-generator-principle-and-structure/07-three-phase-ac-motor-winding/03-2-12-ac-motor-winding.jpg)
![3phase motor winding diagram 3phase motor winding diagram](https://www.industrial-electronics.com/images/elec-mtr-cntrl_31-4.jpg)
The polymer material is organic in its chemical composition and is subject to change due to aging, carbonization, heat, or other adverse conditions that cause a chemical composition of polymer material to change. When motor windings fail it’s very seldom that the actual conductors fail, rather it is the polymer coating (insulation) surrounding the conductors that fail. Like any other part of the motor, the winding can fail. Motor windings are conductive wires wrapped around a magnetic core they provide a path for current to flow to create then magnetic field to spin the rotor.