Testing Procedure and Ideal Result Values for Power Transformer, CT, PT, Lightning Arrester (LA), Isolator, Circuit Breaker, HT & LT Power Panels:
Power Transformer:
Testing Procedure:
- Turns Ratio Test: Measure the ratio of the number of turns between high-voltage and low-voltage windings.
- Transformer Ratio Test: Verify the rated voltage and current ratios of the transformer.
- Short Circuit Impedance Test: Determine the impedance between the high-voltage winding and the low-voltage winding.
- No-Load Loss and Excitation Current Test: Measure the no-load losses and excitation current of the transformer.
- Load Loss and Impedance Voltage Test: Determine the load losses and impedance voltage of the transformer.
Ideal Result Values:
- Insulation Resistance: Typically, the insulation resistance should be greater than 100 megohms.
- Turns Ratio: The measured turns ratio should match the specified ratio.
- Transformer Ratio: The measured voltage and current ratios should be within the specified limits.
- Short Circuit Impedance: The measured impedance should match the manufacturer's specifications.
- No-Load Loss and Excitation Current: The no-load losses should be within the specified range, and the excitation current should be minimal.
- Load Loss and Impedance Voltage: The load losses and impedance voltage should be within the specified limits.
Current Transformer (CT):
Testing Procedure:
- Ratio Test: Measure the ratio of primary to secondary turns using a standard voltage injection method.
- Polarity Test: Determine the correct polarity of the CT with respect to the primary current direction.
- Saturation Test: Apply a gradually increasing current to check for saturation of the CT.
- Burden Test: Verify the accuracy of the CT under different load conditions.
Ideal Result Values:
- Ratio Test: The measured ratio should match the specified ratio within a defined tolerance.
- Polarity Test: The polarity should be correct to ensure the correct phase relationship with the primary current.
- Saturation Test: The CT should not saturate within its specified current range.
- Burden Test: The CT should accurately measure the current under different load conditions within the specified accuracy limits.
Potential Transformer (PT):
Testing Procedure:
- Ratio Test: Measure the ratio of primary to secondary voltages using a standard voltage injection method.
- Polarity Test: Determine the correct polarity of the PT with respect to the primary voltage direction.
- Insulation Resistance Test: Measure the insulation resistance between primary and secondary windings.
- Burden Test: Verify the accuracy of the PT under different load conditions.
Ideal Result Values:
- Ratio Test: The measured ratio should match the specified ratio within a defined tolerance.
- Polarity Test: The polarity should be correct to ensure the correct phase relationship with the primary voltage.
- Insulation Resistance: The insulation resistance should be greater than a specified value to ensure proper isolation.
- Burden Test: The PT should accurately measure the voltage under different load conditions within the specified accuracy limits.
Lightning Arrester (LA):
Testing Procedure:
- Insulation Resistance Test: Measure the insulation resistance of the LA.
- Voltage Withstand Test: Apply a high voltage to check if the LA can withstand the specified voltage.
Ideal Result Values:
- Insulation Resistance: The insulation resistance should be greater than a specified value to ensure proper isolation.
- Voltage Withstand Test: The LA should be able to withstand the specified voltage without breakdown.
Isolator:
Testing Procedure:
- Mechanical Operation Test: Verify the smooth operation of the isolator mechanism.
- Contact Resistance Test: Measure the resistance across the isolator contacts.
Ideal Result Values:
- Mechanical Operation Test: The isol
Isolator should operate smoothly without any jerks or sticking.
- Contact Resistance: The resistance across the isolator contacts should be as low as possible to minimize power loss and heating.
Circuit Breaker:
Testing Procedure:
- Mechanical Operation Test: Verify the smooth operation of the circuit breaker mechanism.
- Contact Resistance Test: Measure the resistance across the circuit breaker contacts.
- Timing Test: Measure the opening and closing times of the circuit breaker.
- Trip Coil Test: Verify the proper functioning of the trip coil.
Ideal Result Values:
- Mechanical Operation Test: The circuit breaker should operate smoothly without any jerks or sticking.
- Contact Resistance: The resistance across the circuit breaker contacts should be as low as possible.
- Timing Test: The opening and closing times should be within the specified limits.
- Trip Coil Test: The trip coil should function properly, ensuring the circuit breaker trips when required.
HT & LT Power Panels:
Testing Procedure:
- Insulation Resistance Test: Measure the insulation resistance between live parts and ground.
- Phase Sequence Test: Verify the correct phase sequence of the incoming supply.
- Busbar Continuity Test: Check the continuity of busbars throughout the panel.
- Earth Fault Loop Impedance Test: Measure the impedance of the earth fault loop.
- Functional Tests: Verify the operation of various components, such as switches, indicators, and relays.
Ideal Result Values:
- Insulation Resistance: The insulation resistance should be greater than a specified value to ensure proper isolation.
- Phase Sequence Test: The phase sequence should be correct to prevent phase reversal issues.
- Busbar Continuity: The busbars should have low resistance, ensuring good conductivity.
- Earth Fault Loop Impedance: The impedance should be within the specified limits to ensure proper operation of protective devices.
- Functional Tests: All components should operate as intended, indicating proper functionality of the power panel.
Note: The ideal result values may vary depending on the specific standards and specifications provided by the manufacturers or applicable regulations. It is important to refer to the relevant documentation for specific tolerances and limits during testing.
Comments