Description

Megger MCT1605 Current Transformer Test

The Megger MCT1605 test set is a lightweight, robust, portable unit used to automatically or manually perform saturation, ratio, polarity, demagnetizing tests and insulation tests on current transformers. The MCT provides a microprocessor controlled variable voltage output and precision instrumentation for automatically testing single and multi-ratio CTs. The MCT1605 possesses microprocessor controlled output voltage with precision instrumentation and storage, reducing testing time and increasing productivity. The MCT1605 will directly connect to multi ratio CT’s and perform all three tests – saturation, ratio and polarity – on all taps with the push of a button and without changing leads. The MCT1605 has a large display, permitting the user to easily read all pertinent data while the test is being performed and providing the ability to view the current transformer’s saturation curve.

Current transformers can be tested in their equipment configuration, such as being mounted in transformers, oil circuit breakers or switchgear. It is necessary for the equipment to be completely isolated from the electrical system prior to testing.

Saturation Test

With the single push of a button, The MCT1605 performs a CT saturation test and calculates the rated knee point. The saturation test is performed at mains rated frequency of 50 or 60 Hz as required by IEC regulations. The MCT1605 will calculate the rated knee point in compliance with IEEE C57.13.1, IEC 60044-1 or IEC 60044-6. While the saturation test is being performed, The MCT will plot the CT saturation curve on the large graphical display and automatically provide the user with the rated knee point per the desired IEEE or IEC standard. Many substation CT’s include a multi-ratio secondary, therefore the MCT1605 has the ability to plot and simultaneously display up to 10 CT saturation curves.

Ratio Test

Ratio testing is performed by comparing a voltage applied to the secondary winding to the resulting voltage produced on the primary winding. For example, if 1 volt per turn is applied to the secondary winding, the voltage present on the primary winding would be 1 volt. More specifically, if 120 volts were applied to the secondary of a 600/5 current transformer (120:1 ratio), 1 volt would be present on the primary winding. This test is performed automatically during a CT saturation test or manually with the output control knob and metering display. The MCT1605 will also provide the operator with a direct reading ratio, thus removing the need to calculate CT ratio manually.

Polarity Test

Polarity of the current transformer under test is indicated to the operator by a simple “Correct” or “Incorrect” indication on the display accompanied by the measured phase angle.

Demagnetization

Normal operating conditions and typical winding resistance measurements can cause a CT to become magnetized. The MCT1605 has the ability to automatically demagnetize the CT under test. This automatic demagnetization routine is useful to ensure that the CT Saturation test yield correct results. Prior to testing demagnification is recommended per ANSI C57.13.1.

CT Burden Measurement

In addition to performing any required CT test, the MCT1605 has the ability to measure the actual connected Burden. When the actual measured burden is compared against the calculated burden, the user confirms that the CT will operate with published rating.

Insulation Resistance Test

In order to ensure that the CT secondary wiring is properly insulated, the MCT1605 system includes a 500/1000V insulation resistance test system. This test ensures that the CT secondary winding and secondary wiring is properly insulated per ANSI C57.13.1.

The MCT1605 will also automatically switch the test leads to perform all required insulation test. These test include H-L, H-G, L-G Note: Disconnect all electronic loads before performing this test.

Winding Resistance

Measuring the DC resistance of transformer windings will aid in identifying problems such as shorted or open windings as well as loose connections.

Data Storage and Printing

The MCT1605 test system not only permits accurate and automated CT testing, but also catalogues and stores test results within the instrument for simple retrieval by software at a later date. All catalogued test results can be uploaded to Megger’s PowerDBTM Lite for report generation and saturation curve plotting on a computer. PowerDB Lite also has the ability to operate the MCT1605 with no operator intervention, thus providing a completely computer controlled automated test system.