Physical Test Low voltage cable

Описание: Physical Test Low voltage cable
Physical tests for low voltage cables ensure safety and performance, primarily involving Insulation Resistance Megger tests , Continuity tests, checking for Cross-Phasing/Polarity, and sometimes Low Resistance Ohmmeter DLRO tests for connections, all done with a calibrated Megger before and after installation to verify integrity against moisture and damage.
Key Physical Tests
Insulation Resistance IR:
Purpose: Checks insulation integrity between conductors and to earth.
Method: Apply 500V DC or 1000V DC for 1 minute.
Acceptance: Minimum 100 Megohms, though manufacturer's data is best.
Continuity Test:
Purpose: Ensures all conductors are intact and correctly connected.
Method: Use a low-resistance ohmmeter to check for breaks or shorts in each conductor.
Cross-Phasing/Polarity Test:
Purpose: Verifies correct conductor identification to prevent fault conditions.
Method: Checks for correct color coding and phasing, essential for correct machine rotation.
Low Resistance Ohmmeter DLRO Test:
Purpose: Measures resistance of bolted connections and parallel conductors for high-quality termination.
Method: Use a DLRO to check bolted connections and compare resistance across parallel conductors.
Visual Inspection:
Purpose: Detects physical damage, contamination (e.g., metal oxides at terminations), or incorrect installation.
Method: Check for sheath damage, proper bending, and clean, tight terminations.
Tools Used
Megger: For insulation resistance tests.
DLRO: For continuity and connection resistance.
When to Test
Before installation .
After laying and before final connection/energization.