Instruction Manual ct-t1
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- Điều hướng trang này:
- 3.3.3. CT Turns Ratio Test
- 3.3.4. CT Polarity Test
- 3.3.5. CT Excitation Test
- 3.3.6. VT Turns Ratio Test
- 3.3.7. Limitations of Testing
| 3.3.2. CT Demagnetizing
The Raytech CT-T1 demagnetize CT before performing tests and measurements. The method is based on IEEE C57-13-1 standard. This can help to get rid of previously induced magnetization and so measure signals accurately. 3.3.3. CT Turns Ratio Test The Raytech CT-T1 can measures the turns ratio of current transformers from various types. This test can help to prove that the measured ratio is true according to name plate of CT and also can be used to determine that the taps wired and labeled correctly in multi-ratio current transformers. 90225-1.30 Instruction Manual CT-T1 Page 9 of 62 3.3.4. CT Polarity Test CT polarity test in Raytech CT-T1 can be used to determine the direction of secondary current flow for a given direction of primary current flow. Determining polarity is required in cases such as: • current transformers connected together in parallels or in series • secondary currents are summed or compared in differential mode • energy metering systems 3.3.5. CT Excitation Test The Raytech CT-T1 can perform excitation test on current transformers from various types and on both C and T class CTs. Calculated excitation curve and calculated knee points can be used to making comparison between new test data and past test data or factory data in order to: • confirm the CT accuracy rating • find shorted turns in windings • check that there is no wiring or physical short circuits in windings after installation 3.3.6. VT Turns Ratio Test The Raytech CT-T1 can also used to measure the turns ratio of voltage transformers. The measured turns ratio can be compared to nominal turns ratio value in order to determine the correct operation of VT. 3.3.7. Limitations of Testing In general, there are no limitations on testing low or high turns ratio or knee points. The test system is specially designed to test all current transformers and voltage transformers in the output voltage and current ranges specified in Chapter 9. 90225-1.30 Instruction Manual CT-T1 Page 10 of 62 |