winding resistance meter, specially designed for field testing as well as factory testing of large transformers up to 500MVA. Winding resistance value of transformer and rotating machine are directly displayed on 5.7” TFT display. TRM25 is designed to work in live EHV switchyard conditions, ensuring operator’s safety and repeatability of results. Maintenance time saving is ensured by one time connection to transformer with simultaneous resistance measurement of three / six windings , measurement of resistances of all taps with automated tap change and demagnetisation facility. The meter is protected against the back-EMF offered by large inductive windings.
- Can measure DC winding resistance of large rotating machines, highly inductive test objects like Transformer, Generators and Motors etc.
- 25 A DC current makes it possible to measure low resistances with high accuracy.
- One time connection to either all windings of primary and / or secondary. Simultaneous measurement reduces connection and measurement time.
- Change in winding resistance, short or open windings can be detected from measured values.
- Automatic temperature measurement and temperature corrected value calculation.
- Measurements of winding resistance of all taps of phases in one go. Recoding, printing and storage of results.
- OLTC contact opening and compete OLTC performance test facility. Testing of either single or three phases in one test. Single report generation.
- To know condition of OLTC contacts, OLTC mechanism, transition resistor.
- Discharges and demagnetizes the object after test
- Uses Kelvin’s 4 wire method for resistance measurement.
- Designed to measure DC winding resistance of highly inductive objects like transformers, generators, motor etc.
- 30V / 50V* DC open circuit voltage.
- Simultaneous measurement of 1 / 2 / 3* windings.
- Quick stabilization of test results
- Direct readings of all channels on backlit LCD
- Automatic back-emf discharge with indication
- Simple setup and use.
- OLTC discontinuity indication
*- Features available only in TRM25
- Displays, prints and stores test reports in the form of text header and tabulated test results.
- Stand-alone & PC control mode
- Managed by powerful CTrans software to configure setup, conduct test, view & analyse results, generate test report.
- Current range selection, enable / disable of channels, printing, downloading etc.
- 25A / 10A / 5A / 1A / 0.1A / 0.01A DC current injection range. Resistance auto-ranging.
- Inbuilt thermal printer for test results.
- Temperature measurement channel and automatic temperature correction for winding resistance for copper & aluminum windings. Supplied with RTD temperature sensor.
- OLTC dynamic test facility available optionally.
Tap changer failures account for more than 40 % of all failures on power transformers. OLTC failures are caused by degradation of OLTC contacts. SCOPE offers dynamic OLTC test facility with TRM 25 to identify weaknesses in OLTC assembly. The test is conducted in PC control mode at higher sampling speed of 10 KHz.
- This test records variation in current flowing through the OLTC against time during tap change.
- Gives % drop in current and transition time
- The drop in current during OLTC transition indicates change in transition resistance.
- I t is also possible to calculate transition time which shows healthiness of mechanism.
- The test is very useful for assessing health of OLTC.
This optional feature extends the capability of the basic instrument making it complete test equipment for testing transformers.
|Temperature Channel||Not Available||Yes|
|Current Ranges||1A, 0.1A, 0.01A||10A, 1A, 0.1A, 0.01A||25A, 10A, 5A, 1A, 0.1A, 0.01A|
|Maximum Resistance Range||2000Ω||2000Ω||2000Ω|
|Accuracy||Value ± 0.5% ± 2 digits|
|O/C Voltage||30V DC||50V DC|
|Protection||Back EMF, Over Temperature, Accidental Disconnection of Lead|
|OLTC Discontinuity indication||Yes|
|Display||4 Line 20 character backlit LCD for Resistance & Test Current||256 X 128 pixel, backlit graphic LCD for Resistance & Test Current|
|Dimension||475 x 405 x 175 mm||475 x 405 x 230 mm||585 x 480 x 195 mm|
|Instrument Weight||10 kg||15 kg||20 kg|
|OLTC Dynamic Test||No||Yes (Optional)|