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High Voltage Test Solutions

As part of the commissioning, maintenance or diagnostic procedures, it is typically used on field a high voltage test for condition assessment of the electrical equipment; there are many high voltage test techniques for transformers, breakers, generators, power cables, and other devices designed to operate under medium or high voltage conditions; typical high voltage test applications are for example the insulation resistance testing, dielectric testing, withstand testing, etc.

Consequently, we can find different high voltage test equipment, which are designed accordingly to the specific requirements and different test signals range and type for each device; a high voltage test may be based in AC or DC voltage injection, with different objective sought and techniques to be applied; the following EuroSMC equipment are products which use a high voltage test for different test and measurement purposes.

EuroSMC products suitable for high voltage test applications in transformers, motors and generators

It is typical the use of high voltage tests on transformers to confirm their performance, which leads to get different parameters such as insulation resistance, degradation of the insulation, dielectric rigidity, voltage ratio, magnetizing characteristic, leakage currents, etc.

The following EuroSMC equipment are suitable for high voltage test in transformers, among other applications:

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The CV-05 configuration is the minimum required to perform a high voltage test with the Raptor System, and it is formed by the Raptor Master unit and the high voltage test unit, the Raptor HV.

High voltage test

A typical high voltage test performed in all kind of CTs, VTs and PTs is the dielectric rigidity test, or withstand voltage test, through which is checked that the leakage current is below a preset safety limit for the test voltage signal; it is a non destructive high voltage test which verify the insulation integrity of the equipment and checks if the transformer dielectric strength is in suitable condition for the service, capable of withstanding overvoltages during operation.

The Raptor includes a template for determining the transformer turns ratio in voltage transformers, as well as the polarity, phase angle between primary and secondary, and the connected burden, for which just the Master unit can be used, but the use of higher voltage values in the ratio minimize the errors, so that it is more advisable the high voltage test provided by the use of the Raptor HV unit; similarly, the use of the CV-05 provides lower errors in the measured values in the corresponding test templates for PT voltage ratio test and PT short-circuited test included in the Raptor System.

The CT magnetization automatic test is included in the Master unit up to 200 V, which is sufficient for measuring CTs, but not for protection CTs which may eventually need more than 1000 V to saturate; therefore, for protection CTs it is used the high voltage test capacity up to 2000 V provided by the HV unit, which also requires a much simple connection, just connecting the voltage injection cables in the transformer secondary, since the excitation curve and knee point measurements during the high voltage test are performed by the built-in ammeter and voltmeter of the HV unit.

It is also needed to highlight that the power of high voltage injection of the Raptor HV unit allows for performing Step & Touch voltage measurements in the protective earthing installations of substations and other electrical facilities, and also for performing a high voltage test in voltage sensors and converters which requires that suitable voltage range.

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For more information, please check the related EuroSMC products or contact us.