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Relay and current transformer test set


  • MRCT
  • Overview  
  • Application  
  • Downloads  
  • Industry leading test duration using patented simultaneous multi-tap measurements reduces testing time by 20% on multi-tap CTs
  • Accuracy to support testing of metering and protection class CT
  • Integrated single phase relay test system
  • Grouped testing: demagnetization, knee points, ratios, saturation curves, winding
  • resistance insulation and more
  • Measure all ratios and saturation curves on multi-tap CTs with one lead connection
  • Optional DC excitation technique for testing CTs with kneepoints up to 30 kV
  • Optional Integrated VT/CVT test system

The Megger MRCT is a light weight, robust, portable unit used to perform demagnetization, ratio, saturation, winding resistance, polarity, phase deviation, and insulation tests on current transformers. The MRCT automatically calculates ratio errors, saturation curves, and knee points. The MRCT provides a microprocessor-controlled variable voltage and current output and precision instrumentation for automatically testing single and multi ratio CTs, reducing testing time and increasing productivity. The MRCT will directly connect to multi ratio CT’s and perform all tests – saturation, ratio and polarity, winding resistance and insulation – on all taps with the push of a button and without changing leads.

The MRCT can be controlled via Megger’s Smart Touch View Interface (STVI) controller, a full color, high resolution, LCD touch screen which allows the user to perform manual and automatic testing quickly and easily using the manual test screen, as well as using pre-constructed test routines. The large display permits the user to easily read all pertinent data while the test is being performed and provides the ability to view the current transformer’s saturation curve. The unit can also be configured to come without a Megger STVI and can be controlled via a laptop with Megger’s PowerDB software.

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 MRCT performs a CT saturation test and calculates the rated knee point. The saturation test can be performed at frequency of 50 or 60 Hz up to 2,000 volts as required by IEC regulations.

The MRCT will calculate the rated knee point in compliance with either IEEE C57.13.1, IEC 60044-1, IEC 60044-6 or IEC 61869 on both standards as well as of specialized CTs such as PX, TPS, TPX, TPY and TPZ. While the saturation test is being performed, the MCRT will plot the CT saturation curve on the STVI display and automatically provide the user with the rated knee point per the desired IEEE or IEC standard. Many substations CTs include a multi-ratio secondary; therefore the MRCT has the ability to plot and simultaneously display up to 10 CT saturation curves.

Ratio, Polarity Test

Ratio testing can be performed by using the MRCT. The method used by the MRCT compares 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.

Winding Resistance Test

Measures CT winding resistance with the injection of a test voltage, measuring the DC current and calculating temperature compensated resistance.


Normal operating conditions and typical winding resistance measurements can cause a CT to become magnetized. The MRCT 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 demagnetization is recommended per both ANSI and IEC standards.

CT Burden

The MRCT measures the connected CT burden load with direct injection of secondary current to a load that is disconnected from the CT. The MRCT measures the secondary voltage in magnitude and angle of the connected burden in VA and power factor.

Insulation Resistance Test

In order to ensure that the CT secondary wiring is properly insulated, the MRCT system includes a 500 V, 1,000 V insulation resistance test system. This test ensures that the CT secondary winding and secondary wiring is properly insulated per both ANSI and IEC standards .

The MRCT 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.

Data Storage and Printing

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


The MRCT includes the ability to upgrade testing capability. With various configurations and accessories the MRCT system can be upgraded as new testing needs are developed.