Power Cable Systems (LV/MV/HV)

✅ QA/QC Checks:

Cable Type & Sizing Validation:

Verify against load schedule, voltage drop calculations, and short-circuit withstand (IEC 60287, IEEE Std 835).

Manufacturer’s CoC (Certificate of Compliance):

Confirm conductor material (Cu/Al), insulation (XLPE, PVC), armoring, flame retardance (IEC 60332).

Pre-installation Inspections:

Reel handling, storage (UV protected, upright), cable ends sealed.

Check drum rotation direction (to avoid twist/kink).

✅Testing:

Insulation Resistance Test:

1000V megger for LV, 5kV for MV, before and after installation (as per IEEE 400).

VLF or Tan Delta Testing (MV/HV cables):

Identifies insulation deterioration.

HiPot Test:

Used if required, but caution: it may stress insulation if overdone.

✅Common QA Issues:

Poor gland sealing → Water ingress → Cable failure.

Incorrect bending radius → Micro-cracks in insulation.

Mislabeling → Operational errors.

✅Factory Acceptance Testing (FAT):

Wiring Diagram Verification: Control/schematic drawings vs. actual.

Component Check: Verify compliance with BOQ/spec (brand, type, rating).

Functional Tests:

Breaker tripping curves.

Protection relay operation.

Phase sequence check.

Interlock tests (mechanical/electrical).

✅Field QA/QC Inspections:

IR testing of Busbars: 1kV or 500V depending on panel class.

Torque Testing: As per manufacturer’s recommendation (torque wrench log required).

Thermal Scanning (post-energization):

Detects hot spots, loose terminals.

✅ Common Faults:

Loose CT/PT secondary connections → Incorrect metering/protection.

Underrated busbar size → overheating.

Missing shrouds → Safety violation.

✅ Pre-installation Inspection:

Confirm core and coil insulation resistance.

Check oil BDV (breakdown voltage) > 60 kV is ideal.

Ensure breathers are filled with blue silica gel.

Verify N2 pressure inside sealed transformers (2–6 psi).

✅Site Tests:

IR, Ratio, and Vector Group Test (IEC 60076).

Magnetization Curve & Short Circuit Impedance Test (for critical installations).

Tan Delta and SFRA for high-value transformers.