Test On 110kV Power Cable After Installation - Part 2

General description of site test procedure

In previous part of this technical article first three procedures were explained. Now the rest will be explained in details:

1. Phase indication test (previous part)
2. DC conductor resistance measurement (previous part)
3. Capacitance test (previous part)
4. DC Sheath test on outher sheath
5. Insulation resistance measurement
6. Cross bonding check
7. Zero sequence and positive sequence impedance test (next part)
8. Earth resistance measurement at link boxes (next part)
9. Link box contact resistance measurement (next part)

4. DC sheath test on outher sheath

The test is applied when the cable sheath can be isolated from the earth to permit a voltage to be applied to the over-sheath to check the integrity of the covering.
This testing is generally applied at certain stages of cable system installation at specified parameter as follows:

1. When the cable is still on reel. The applied test voltage is 10 kV for 10 seconds, if a proper test lead is provided.
2. Once the cable are laid, dressed and tied together in trefoil configuration a test voltage of 10 kV for 30 seconds is applied.
3. Following backfilling sand beddind-2, a test voltage of 10 kV is applied for 1 minute on each cable. This is a formal testing with test records and signed by representatives of the responsible parties as witnesses.
4. Following completion of jointing activities between two cable sections in a joint bay and after backfilling of the joint bay, the jointed cable sections are then tested by applying 10 kV for 30 seconds.
5. Following the completion of cable system installation and prior to acceptance testing, as a pre-check testing a test voltage of 10 kV is applied for 1 minute.

Note – All above mentioned testing will be conducted in presence of project consultant.

References

• IEC 60840 – Power cables with extruded insulation and their accessories for rated voltages above 30 kV
• IEC 60229 – Electric cables // Tests on extruded oversheaths with a special protective function
• TES-P-104.08 – Bonding and grounding of insulated metallic sheath of power cable system

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Test On 110kV Power Cable After Installation - Part 1

Cable selection and application

It is essential to know cable construction, characteristics, and ratings to understand problems related to cable systems. However, to correctly select a cable system and assure its satisfactory operation, additional knowledge is required. This knowledge may consist of service conditions, type of load served, mode of operation and maintenance, and the like.

The key to the successful operation of a cable system is to select the most suitable cable for the application, make a correct installation, and perform the required maintenance.

In this technical article, discussion is based on the correct cable selection and application for power distribution and utilization.

General description of site test procedure

Site test procedure covers all necessary electrical testing for the 110 kV cable and accessories to be carried out during and after installation of the cable system.

This procedure is in line with the requirements of the contract suitable for 110 kV, XLPE cables and accessories and the tests are in accordance with TCSP-104.08, IEC 229, IEC 540 and IEC 840.

110 kV, 115 kV and 132 kV XLPE Cables

(Standard Reference is IEC 60840 and relevant SEC Transmission Specifications 11-TMSS-02, Rev. 0 and TCS-P-104.02, TCS-P-104.03, TCS-P-104.06 and TCS-P-104.08)

1. Mechanical Check and visual Inspection

ITEM	Description	Remark
1	Inspection for physical damage or defects
2	Check tightness of all bolted connections (torque wrench method)
3	Check for proper cable bolted connections
4	Check cable bends to ensure that bending radius is equal to or greater than the minimum bending radius specified
5	Check for proper cable support, clamping, trays arrangements
6	Link box tightness check
7	Verify that shields are terminated as specified (through link box or directly grounded)
8	Verify the exact route length as per approved drawings from terminations to terminations
9	Check that all grounding points are securely connected to ground grid as specified
10	Check that phases are identified and color coded
11	Single core cable connected between power transformer and switchgear shall be single point earthed as switchgear side and at floating side SVL (sheath voltage limiter) should be installed
12	Check single point or both ends, via voltage limiter as per approved design
13	Inspection of label inside link boxes and water proofing
14	Check cable entry path trench as ducts are properly sealed
15	Check irregularities of outer jacket formed by non-uniform shield wire distribution
16	Check/inspect the transposition of cable phases
17	Check the cable outer jacket for any physical damage during and after installation
18	Check for the cross connection of cable metallic sheath in cross bonding system
19	Check the rubber seal in cable clamps to avoid any damage to cable outer jacket
20	Check the insulating shrouds are installed at the base of the cable terminations
21	For accessories (sealing terminations, instrument panels and link boxes) check the following:
	a. Name plates installed and data is correct
	b. Danger signs
	c. Bolt tightness check and paint work conditions

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