Question
Download Solution PDFThe current plug settings usually range from 10% to 70% in steps of _________ for earth leakage relays.
This question was previously asked in
NHPC JE Electrical 5 April 2022 (Shift 1) Official Paper
Answer (Detailed Solution Below)
Option 3 : 10%
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NHPC & THDC JE Civil Full Test 1
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Detailed Solution
Download Solution PDFEarth leakage relays:
- The earth leakage relay is an electronic device that detects earth failures.
- This device operates by sensing earth leakages and opening a circuit breaker when the leakage current exceeds the preset value.
- The current plug settings usually range from 10% to 70% in steps of 10% for earth leakage relays.
- Earth leakage relays are used in combination with core balance current transformers.
- Under normal conditions, the vector sum of the current flow in phase and neutral will be zero.
- Earth faults cause an imbalance in the current flow in the phase and neutral conductors.
- Core balance current transformers or zero-phase current transformers are used to sense this current imbalance.
- The earth fault relay continuously monitors the output of the core balance current transformers.
- When its output exceeds the present limit, the relay contacts operate.
- These relay contacts are used to activate the trip contacts of the circuit breaker and trip it.
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