MEGGER

Current Transformer Testing

The need for a comprehensive current transformer testing regime is evident when the alternative is considered: a catastrophically damaging current transformer fault. A fault leading to an open secondary could cause the primary current to overwhelm the insulation, causing the winding to short circuit. Megger’s range of current transformer test equipment allows you to construct an in depth test and maintenance programme to prevent problems before they occur.

A routine series of diagnostics and testing for your current transformer should include CT saturation testing to identify the knee point against IEEE or IEC standards, CT ratio tests to identify that the voltage ratio is within expected parameters and current transformer resistance testing for both the transformer windings and CT insulation resistance testing.

Saturation testing for a current transformer identifies the rated knee point against IEEE or IEC standards, the point at which the transformer is no longer able to output current in proportion to its specified ratio.

Ratio tests under normal load are achieved by comparing voltage applied to the secondary winding against the resulting voltage produced on the primary winding. Current transformer resistance tests inject test voltage to measure the DC current and calculate the resistance with allowance for temperature. 

BA-185
CURRENT TRANSFORMER BURDEN AMMETER

  • Rugged
  • Portable
  • Multirange ammeter with switch-selected burdens
The BA-185 Current Transformer Burden Ammeter is a rugged, portable instrument, designed to field-test current transformer installations for:
  • Short-circuited secondary turns
  • Short-circuited primary turns
  • Short-circuited secondary wiring
  • High-resistance connections in the secondary circuit
  • Grounding of secondary winding when mounted on a grounded structure
  • Grounding of a normally ungrounded wire

MAGNUS
STEP-UP TRANSFORMER

  • Quick and easy preparation of excitation curves for instrument transformers
  • Demagnetize current transformer cores
  • Conduct turn-ratio tests on voltage transformers
  • Two-hand control enhances personal safety
When power systems are put into operation or when faults occur, it becomes necessary to check the instrument transformers to make sure that they are providing test instruments and protective relay equipment with the correct outputs.

MAGNUS™ permits you to prepare excitation curves for instrument transformers quickly and easily.

MAGNUS is also used to demagnetize current transformer cores and to conduct turn-ratio tests on voltage transformers. Even though it weighs only 16 kg (35 lbs), it provides 1 A at 2.2 kV. Two-hand control enhances personal safety.

As standard, MAGNUS is delivered with a special high-voltage cable and a robust transport case.

MRCT
RELAY AND CURRENT TRANSFORMER TEST SET

  • 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.

MVCT
VT & CT ANALYZER

  • Ability to test both VT and CT
  • Easy to use one-button automated test plans
  • Industry leading test duration using patented simultaneous tap measurements
  • Smallest and lightest unit on the market
  • CT Kneepoints up to 30kV
  • CT grouped testing includes Demagnetization, Knee Points, Ratios, Saturation Curves, Winding Resistances, Polarities and Phase Deviation (on all taps of multi-ratio CTs)
  • VT testing including Demagnetization, Ratio, Winding Resistance, Polarity and Phase Deviation
  • Performs Secondary Burden tests
  • Integrated 1 kV DC insulation test system
The Megger MVCT test set is a lightweight, robust, portable unit capable of testing both current and voltage transformers. At less than 20 lb (10Kg) the MVCT is a highly portable unit that also offers accuracy in testing. Capable of performing saturation, ratio, polarity, winding resistance, and insulation tests on current transformers, the MVCT can also be used for testing metering and protection class voltage/potential transformers. The MVCT provides a microprocessor controlled variable voltage and current output along with precision instrumentation for automatically testing single and multi-ratio CTs and VT’s. The MVCT makes testing CTs easy. It 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. This greatly reduces testing time. The MVCT can be controlled via its large, full color, high resolution, sunlight readable TFT LCD touch screen display. This interface allows the user to perform manual and automatic testing quickly and easily using the manual test screen, or by using pre-constructed test routines. The large color display also permits the user to easily read all pertinent data while the test is being performed and provides the ability to view the results when the test is complete. The unit can also be configured to come without a display and thus be controlled via a laptop utilizing PowerDB or with Megger’s existing Smart Touch View Interface™(STVI). 
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