Transformer pre-commissioning tests ensure that a transformer is fit for service before it is energized. These tests help identify any issues or faults that may be present, so they can be addressed before the transformer is put into operation. Here are detailed transformer pre-commissioning tests with specific values:
Electrical Tests
1. Winding Resistance Test: Measures winding resistance to ensure correct connections.
- Test voltage: 1-10V DC
- Tolerance: ±1% of rated resistance
We have different models of transformer winding resistance testers, from 10A to 100A, single phase and three phase, to be selected.
2. Insulation Resistance Test: Verifies insulation integrity.
- Test voltage: 500-1000V DC
- Minimum resistance: 100 ΜΩ (megohms)
BC2030 insulation resistance tester can do the test for transformer. It can display the PI&DAR directly.
3. Polarity Test: Confirms correct phase sequence.
- Test voltage: 100-400V AC
4. Ratio Test: Verifies transformer turns ratio.
- Test voltage: 100-400V AC
- Tolerance: ±0.5% of rated ratio
BBC-HI transformer turn ratio tester can do ratio test and polarity test, it can also test the victor group of transformer directly.
5. No-Load Loss Test: Measures transformer losses at no-load.
- Test voltage: Rated voltage
- Maximum loss: As per manufacturer's specifications
RLS-H transformer capacity &No-load loss tester can test this, it need to be matched with voltage regulator when test no-load test.
Dielectric Tests
1. Dielectric Strength Test: Verifies insulation strength.
- Test voltage: 2-3 times rated voltage (50/60 Hz)
- Test duration: 1 hour
Our AC/DC hipot tester can do the dielectric strenght test for transformer, you can choos the suitabe model based on the test requirement.
2. Partial Discharge Test: Detects insulation defects.
- Test voltage: 1.5-2 times rated voltage
- Frequency: 50/60 Hz
Non-PD test system can conduct the offline PD test for transformer
3. AC Voltage Withstand Test: Verifies insulation withstand capability.
- Test voltage: 2-3 times rated voltage (50/60 Hz)
- Test duration: 1 hour
Our AC/DC hipot tester can do the dielectric strenght test for transformer, you can choos the suitabe model based on the test requirement.
Transformer Oil Tests
1. Oil Dielectric Strength Test: Measures oil insulation strength.
- Test voltage: 30-50 kV
- Minimum dielectric strength: 30 kV
Our JYY-HI Oil BDV tester has single cup and the voltage is up to 80KV.
2. Oil Moisture Content Test: Measures oil moisture content.
- Maximum moisture content: 2% (by weight)
YWS-2 oil moisture content tester has high accureny and performance, easy to operate and portable.
3. Oil Acidity Test: Measures oil acidity.
- Maximum acidity: 0.5 mg KOH/g
We have the YSZ-H oil acidity tester to test the acid value of transformer oil. It is easy to operate and high performance.
Physical and Visual Tests
1. Visual Inspection: Checks for physical damage or defects.
2. Tightness Test: Verifies electrical connections.
3. Transformer Oil Level Check: Ensures adequate oil level.
4. Cooling System Check: Verifies cooling system functionality.
Control and Protection System Tests
1. Protection Relay Test: Verifies protection relay functionality.
2. Control Circuit Test: Tests control circuit operation.
3. Alarm and Interlock Test: Verifies alarm and interlock functionality.
Safety Tests
1. Earth Fault Test: Verifies earth fault protection. You can use DER2571 earth resistance tester to check, or use earth fault detector
2. Lightning Arrestor Test: Tests lightning arrestor functionality. FC-2GB lightning components tester can be used.
3. Grounding Test: Verifies grounding system integrity.
Standards Compliance
1. IEC 60076-1 (Power Transformers)
2. IEC 60076-2 (Temperature Rise)
3. IEC 60076-3 (Insulation Levels)
4. IEEE C57.12.00 (Standard for General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers)
5. ANSI/IEEE C57.13 (Standard Requirements for Instrument Transformers)
Pre-Commissioning Checklist
1. Review the manufacturer's documentation.
2. Check electrical connections.
3. Test control and protection systems.
4. Perform visual inspection.
5. Conduct safety tests.