ELECTRICAL TEST HIGH VOLTAGE CABLES (5KV-15KV-35KV)
Visual and Mechanical Inspection of High Voltage Cables
- Verify cable reel assignments and cutting schedules.
- Verify cable pulling schedule for direction of pull and method of pulling in conduit for medium voltage cable.
- Verify arrows on cable reels for direction for pulling off reel.
- Verify for correct cable test voltages, minimum pulling temperature and type of pulling compound.
- Inspect cables for jacket damage.
- The conductors are identified as per specification and drawings.
- Cable ends sealed after cutting.
- Verify all water and debris was removed from underground conduit before pulling cable. Verify sweet sand was laid in trench and pulling rollers were appropriately placed before cable was installed.
- Cable supports and spacing as per specifications and drawings.
- Cable supports are adjacent to terminal fittings.
- Conduits clean, stub-ups protected, open ends plugged, damage during construction repaired.
- Field bend radius correct per specification and codes. Bends free of deformities.
- Expansion joints as shown on drawings.
- Spacing between instrument and power conduit and /or cables as per specifications.
- Spacing from hot pipes and from hot surfaces maintained.
- Proper fittings are installed with threads fully engaged, proper sealing compound is used, there are no wrench cuts and conduit ends have bushings and covers installed.
- Seals and drains are installed per drawings.
- PVC or PVC coated conduits are installed where specified on drawings.
- Metal junction boxes leveled and supported per drawings with proper hubs, locknuts and bushings installed.
Seals poured.
ELECTRICAL TEST HIGH VOLTAGE CABLES (5KV-15KV-35KV)
- Cables on reels must be isolated and meggered before unreeling.
- Prepare installed cables for test by ensuring the circuit is de-energized , remove any temporary grounds and disconnect cable form equipment. If equipment cannot be disconnected, a reduced voltage should be used for the test.
- Insulate cable cores from ground.
- Erect safety barriers and post safetyman at cable end remote from the test equipment.
- Check the insulation resistance of the cable using a megger tester. The test voltage should be 5000 volts for 5000 volt and above cables. Measure the insulation resistance of each core and any metallic armor or sheath grounded at one end only.
- Each cable shall be high potential tested as follows: each core to ground, with the shield, other cores and any metallic armor or sheath grounded at one end only.
- For commissioning new cables, the final D. C. test voltage is the 80% test voltage in the tables below.
- For commissioning new cables that are spliced to old cables, and for testing old cables, the final D. C. test voltage shall be determined by the proponent of the cables, and should not exceed the 65% test voltage in the tables below (40% of these values is recommended after 5 years ). A voltage equal to 1.7 X the operating voltage is recommended for extremely old cables with low megger readings.
- The D.C. high voltage shall be applied in a minimum of four steps ( each step approximately equal to the rated rms voltage of the cable) of one (1) minute duration each except for the final test voltage which shall be maintained for fifteen (15) minutes.
- On completion of tests the cable shall be left with all cores and shields grounded for one hour to allow the residual charge to dissipate.
XLPE OR EPR CABLES MANUFACTURED TO AEIC CS5 OR CS6.
XLPE OR EPR CABLES MANUFACTURED TO IEC-502
NOTES: 80% and 65% refer to percentages of the factory test voltages specified in AEIC CS5 and CS6. AEIC CS5 and CS6 permit testing at the 65% test voltage “at anytime during the period of the guarantee.”
Maximum test values for cables older than 5 years are listed in the 40% column.
CABLE TEST RECORD
