Question

Phantom loading for testing of energy meter is used _______.

• A. to isolate the current and potential circuit
• B. to reduce power loss during testing
• C. for meter power loss during testing
• D. to test meter having a large current rating for which loads may not be available

Hint:

Phantom loading = Simulates high load conditions using low power → essential for testing high-current meters.

Answer 1

The Correct Option is D

Step 1: What is Phantom Loading?
Phantom loading, also known as fictitious loading, is a method used in energy meter testing where the voltage and current circuits are energized separately using different sources. The voltage circuit is supplied with rated voltage, and the current circuit is supplied with rated current — but from a low-voltage source.
Step 2: Why is it Used?
When testing high-current meters (e.g., 100 A or more), supplying actual load current from standard testing equipment would require:
- Large power input.
- Significant heating and energy loss.
Instead:
- Current coil is energized at rated current from low voltage (low power loss).
- Voltage coil is energized at rated voltage with small current (again low power loss).
Step 3: Practical Advantage
It allows accurate full-load testing of energy meters without requiring high-power loads, especially useful in labs.
Conclusion:
Option (4) is correct because phantom loading enables testing of high-current meters even when large loads are not practically available.