Safety meets competence

Surge tester

So that you do not get wound up in production – the surge tester from SPS electronic.

Only with a surge voltage test it is possible to detect winding shorts and insulation faults in windings. Preliminary damages and thus a failure of winding materials, electric motors and coils of any kind can be prevented. With a surge tester of SPS electronic you can be certain of the safety of your windings.

In short: What is high voltage testing and how does it work?

The surge test is an established practice in the manufacture of winding goods of all kinds used in the maintenance and repair since the early 1950s, this test is now an integral part in the production of engines, rotors and stators, electric valves and coils of all kinds. To ensure quality, the surge voltage test, also called surge test is not replaceable.

During maintenance and repair the insulation of windings which weakens by aging, vibration, humidity and temperature variations is checked to ensure the production quality during production. Even the quality of the enameled copper wire and iron packets are checked. The classic hipot testing only checks insulation defects of the phases one below the other or in lamination bundles. Defects in the windings go undetected. Here, the physical principle of the surge tests offers the only possibility of viewing the insulation of an individual winding. No measure of the resistance or inductivity can give the results of what a surge test can give.

The principle is that a high voltage pulse is generated by a charged capacitor and is fed to the winding and the subsequent oscillation (L = test specimen, C = tester) is analysed. Due to the very short pulse potential differences between the adjacent windings, or layers of coils are produced. Exactly these potentials are the basis of this assessment: In case of error arising changes, although there is still no galvanic contact. The height of the test voltage and the rise time of the pulses are the decisive factors. Both current pulse as well as the impulse response contains information about the test object. Impedance and quality of the winding are included in the test result. Therefore, all errors are detected, which are affected by these parameters. This includes number of windings, winding geometry and wire errors including interturn and location circuits as well as problems in the magnetic core or laminated core. 

An effect in the surge test: The partial discharge

The partial discharge (PD) is present not only in the conventional hipot test. This effect also occurs at the surge test. Due to the increase of frequency converters in motor control units this test has become very important. As the term "partial discharge" suggests, a complete breakdown does not take place here. Only in one section a partial insulation weakness or underperformance manufactured area is available. This weak point can be loaded during operation or testing far in excess. Therefore, this point does not withstand the increased load and there is a partial breakdown, the partial discharge. The other areas of the insulation can withstand the voltage stress and it does not result in a flashover in the conventional sense. The aim should always be to avoid a partial discharge. What matters is the construction of the test sample and the insulation as well as the level of the test voltage. In practice, it is not necessary to measure the partial discharge (in pico Coulomb). It is sufficient to detect the partial discharge. For this purpose, two methods are used:

  • In manufacturing, a wired connection is preferred in surge test. Interference is less of an issue. 
  • Alternatively, the detection of the high frequency signals through antennas is possible. It is important in this solution to place the antenna in proper position and the avoidance of interference pulses.

We have the right surge tester for you

All surge tester of SPS electronic feature a computer which evaluates both the vibration curve and the partial discharge. Several different methods of analysis are available. In addition, you can also find separate devices for partial discharges, for surge test or for the conventional examination with hipot tester in our product range. The devices operate as stand-alone or via interfaces with a PC - the right software can be found in our product range as well. Both the surge test and the measurement of partial discharge can be combined with other tests in a PC-bound test system. The connection to the various terminals of the test sample happens via high voltage relay in 4-wire technique (Kelvin technique).


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