Click to edit Master title style

Click to edit Master subtitle styleDCT-2000DCT-2000

Digital Current Transformer Reporter

Digital Current Transformer Reporter

CT Purpose

• To accurately reduce the primary current to a value suitable for relays and meters. (5 or 1 amps).

• Provide isolation from the high voltage system.

Testing and Verification

• NETA -National Electrical Testing Association Recommendations:– Perform polarity test.– Perform ratio-verification test using

voltage or current method– Perform an excitation test.– Measure circuit burden.

Ratio and Polarity

• Ratio must be verified so that relays and meters will operate and indicate correctly.

• Polarity must be correct if relays are to “look” in the correct direction, and for meters to indicate correctly.

Ratio and Polarity Errors

• Taps may have been connected to the wrong terminals or may have been labeled incorrectly.

• Wrong number of turns on CT secondary.

• Shorted turns.• Wrong polarity markings.

Saturation Voltage

• Excitation characteristics and saturation voltage must be known to verify that the CT will perform as required by providing required output voltage during fault conditions.

Excitation of Multi-ratio CT

Typical test circuit of variac volt and amp meters

Time Study

• Time to test 5-tap CT (ten ratios and one excitation curve) with older style equipment for:– Ratio– Polarity and phase-angle– Excitation and Saturation– Winding Resistance– Insulation resistance– Time=52 minutes

With DCT-2000x5, time < 5 minutes

Adwel solution

• The DCT-2000 offers the most advanced features in automated multi-ratio CT testing.

• Product available in two models:– DCT-2000x2– DCT-2000x5 – Test Plan Driven

Key Features of DCT-2000x2

• Automated testing of one winding of a CT for:– Ratio– Polarity and phase-angle– Excitation and Saturation– Winding Resistance– Insulation resistance

DCT-2000x2

Test circuit of x2.

Testing Steps of x2

• Enter windings to be tested• Check-off tests to be preformed• Set a voltage limit• Press test• Observe progress• Save test and go the next

winding

Test Screen for x2 ConfiguredNote: x2 does not have test plan

Key Features of x5

• Same as x2 plus:• Automatically tests up to 5 taps

with operator intervention.• Test plan driven.• Provides the ultimate in CT

testing productivity.

DCT-2000x5

Test circuit of x5.

Test ScreenDriven from the Test Plan

Test Plan

The following screens are common to DCT-2000x2 and DCT-2000x5.

CT Info Screen

Extra Results Details

Extra Results Details

Full Graph Screen

Excitation Table Screen

File Manager

Burden Mode up to 20 amps

Other Features

• Saturation voltage (knee point) is calculated.

• Winding resistance is measured• Insulation resistance is measured• Full 75 key keyboard• Store 200 files.• Store 140 test plans in x5.

Other Features

• Up to 2000 Vac output• Up to 2 amps output• Burden output: 20 amp @ 20 volts• Circuit impedance measurement in

burden mode.• Transfer results to PC with USB• Transfer results to memory stick

PC Based Software

• Results stored in database.– Sort on twelve fields.

• Generate full report form including data and color graphs of all curves.

• Files compatible with word processing and spread sheets.

Modes of Operation

• Auto mode:– Allows DCT to automatically complete a

series of tests.

• Manual mode:– Allows operator to manually raise and lower

the voltage to make diagnosis.

• Burden mode:– Current source for secondary injection

Comparison of models

• Both models have identical features regarding tests, output, range, accuracy, keyboard, printer, memory capacity, memory stick, software and database.

• Differences are listed below.

Test Automation

• X2:– Check boxes on test screen are used

to select the tests to be performed in automatic sequence.

• X5:– A test plan conducts the required

tests on up to ten ratios on a multi-ratio CT. Saves 140 plans.

Extent of Automation

• X2:– Completes all selected tests for one

winding.• X5

– Completes all selected tests for up to ten ratios.

Conclusion

• Contact your local representative or Adwel International for questions or further information.