The importance of these tests is that they are the sole test that can detect turn-to-turn insulation weakness. These problems begin with voltages higher than what the engine’s operating voltage is. These weaknesses could lead to catastrophic problems and shut-down of the motor. The tests for surge are also used to detect hard shorts as well as a variety of other faults in coils and windings.
The majority of winding problems, such as grounded shorts, begin by a weak insulation for turn-to-turn. If the flaw causes turn-to turn arcs, an electrically closed loop is formed. Because of transformer action, current is able to flow within the loop. The current then disperses in the form of heat and forms hotspots. The windings are shortened because of the hotspot, and, in turn, more heat is generated. The winding eventually shortens to the ground.
The tests for surge are referred to as surge tests due to the fact that the outcome of a phase or coil is contrasted with the results of another phase or coil. The coils are made to be similar, therefore the surge test results must be similar. When the windings or phases aren’t identical, or there’s nothing to compare them to, the operators can use the pulse-to-pulse surge test.
For more information about surge testing, read Electrom’s piece published in Pumps and Systems magazine:
WHAT CAN BE TESTED BY A SURGE TESTER?
All kinds of coils are capable of being tested, from tiny antennas, sensors and actuating coils found in solenoids or relays to the largest generators and electric motors. Surge tests are a load-dependent test, so the operator must take into consideration the voltage of test norms.
WHICH ISSUES ARE ONLY FOUND WITH A SURGE TEST?
Surge tests are the sole test that can detect weak turn-to-turn insulation. This is because of the higher levels of voltage used in a test. Tests with low voltages do not test the insulation, and therefore weak spots in the dielectric are not discovered.
An adsorption test (also known as a surge) is the sole test that detects weak coil-to coil as well as phase-to phase insulation. Hipot tests are a Hipot test may be employed in cases where phases and coils are tested separately against other coils and phases, but this is not feasible.
Additionally, certain connection errors are discovered only through the use of a surge test. Inductance tests are sometimes utilized, but only if the resistance is in place.