A07 TE 6.5 Electrical Distribution.pdf

TE 6.5 Electrical Distribution Maintenance Procedures

TE 6.5 Electrical Distribution Maintenance Procedures 1

ELECTRICAL DISTRIBUTION SYSTEM MAINTENANCE

The Contractor shall complete the following tasks annually in Option Year 2 and 4:

- Inspect (from ground level) poles for leaning, washout, splitting, lightning damage, and bird damage (wood poles only).

- Inspect (from ground level) wood crossarms for twisting, splitting, decay, loose or missing braces, loose pins, and surface tracking or burning.

- Inspect (from ground level) insulators and bushings for cracks, chips, unscrewed from pin, leaning, and cleanliness.

- Inspect (from ground level) lightning arrestors for cracked, chipped, and broken insulators. Check ground connections. Check for cleanliness.

- Inspect (from ground level) guys and anchors for broken strands, corrosion, looseness and slippage, loose clamps, excessive tension, anchor eye above ground, adequate clearance from conductors, and insulators properly located.

- Inspect (from ground level) conductors for being off insulator, broken strands, blisters or burned spots, excessive or uneven sagging, loose connections, horizontal and vertical clearances.

- Inspect (from ground level) hardware for looseness or corrosion.

- Inspect (from ground level) switches and fuses for general condition, broken arcing horns, bent or misaligned arms.

- Inspect (from ground level) connections for evidence of overheating. Use infrared survey.

- Inspect (from ground level) ground wires for breaks and attachment to pole.

The Contractor shall complete the following tasks annually in Option Year 2:

- Tighten (from bucket truck or by climbing) all hardware on poles (including crossarms, braces, clamps, mounting hardware).

The Contractor shall complete the following tasks in twice annually:

- Trim trees around overhead lines in accordance with the following schedule:

Description OV-750V 750-8.7KV 8.7-13.8KV

Minimum clearance from top of tree. 2'10" 5'0" 8'0"

Minimum clearance from overhanging limbs 5'0" 10'0" Not Permitted

Minimum clearance from primary trunk 2'0" 2'0" 6'0" of tree (includes line sag)

Minimum clearance from primary limb 4'0" 4'0" 7''0"

(includes line sag)

Minimum clearance from branches 5'0" 5'0" 8'0"

TE 6.5 Electrical Distribution Maintenance Procedures 2

(includes line sag)

MANHOLE/VAULT MAINTENANCE

The Contractor shall conduct annually the tasks listed:

- Contractor shall pump the water from all electrical manholes. Contractor shall perform inspections and cleaning in conjunction with pumping.

- Contractor shall perform visual and infrared inspections of power cables in electrical manholes/vaults. Inspection shall be performed during duty day under normal load conditions.

The visual inspections shall include inspection for:

Sharp bends

Physical damage

Excessive tension

Oil Leaks

Pits

Cable movement

Insulation swelling

Soft spots

Cracked jackets in non-lead cables

Damaged fireproofing

Poor ground connections

Deterioration of metallic sheath bonding

Weakened cable supports

Continuity of any main grounding system

Terminations and splices of non-lead cables shall be squeezed in search of soft spots and inspected for tracking of signs of corona.

The ground braid shall be inspected for corrosion and tight connections and maintained.

The bottom surface of power cables shall be inspected for wear or scraping, due to movement, at the point of entrance into the manhole and where it rests on the cable supports.

- The cable identification tags or markings shall be checked and maintained.

- Contractor shall perform an inspection of electrical manholes/vaults for spalling concrete or deterioration and leaks. Manhole/vault drains shall be cleaned.

MEDIUM VOLTAGE TRANSFORMER MAINTENANCE

The Contractor shall complete the following tasks quarterly:

- Inspect transformer temperature, pressure and liquid level, if gauges are present.

Inspect for evidence of oil leakage. Check level of oil in pad mounted, ground mounted transformers and platform mounted transformers.

TE 6.5 Electrical Distribution Maintenance Procedures 3

The Contractor shall complete the following tasks annually:

- Inspect all medium voltage transformers for leakage, clean bushings and clean surfaces.

The Contractor shall sample all pad mounted, ground mounted and platform mounted transformer's oil and test as follows.

The Contractor shall complete the following tests annually:

- Dielectric breakdown of the insulating oil shall be measured IAW ASTM D877 or D1816.

The test shall measure the electrical stress that the insulating oil can withstand without failure.

The Contractor shall complete the following tests once annually in Option Year 1 and 4:

- Neutralization number: The acid content of the oil shall be tested in compliance with

- ASTM D974.

- Color: The numerical value of the color of the insulating mineral oil shall be measured in compliance with ASTM D1500.

- Visual test: Visual condition and sediment shall be IAW ASTM D1524.

- Gas chromatograph Test: Gas chromatography tests shall be IAW ASTM D3612.

- Specific Gravity: Specific gravity of the insulating oil shall be measured in compliance with ASTM D1298.

- Interfacial tension between the insulating oil and water shall be measured in compliance with ASTM D971.

- Perform Karl Fisher Moisture Test.

The Contractor shall complete the following tasks annually in Option Year 2 and 4:

Inspect ventilated (indoor) type transformers

Inspections of operating temperature. Reset drag needle. 150 degrees centigrade is maximum operating temperature for transformers rated 80 degrees centigrade rise. If temperature is above range, redistribute load if possible and notify KO/COR. 220 degrees centigrade is maximum operation temperature for transformers rated 150 degrees rise. If temperature is above range, re-distribute load if possible and notify the

KO/COR.

Cleanliness of screens located over or behind ventilation louvers in enclosure. Vacuum screens of dust or lint on outside of screen.

Ventilation fan operation (if so equipped) Check operation of fans with control switch in

"manual" position. Also check alarm contacts for proper operation at excessive temperature levels.

Room ventilation to ensure adequate ventilation system to admit and exhaust air.

Evidence of condensation and water leaks in room.

Inspect all medium voltage dry transformers for cleanliness of screens, room ventilation, and evidence of condensation or water leaks in room and clean as conditions warrant.

TE 6.5 Electrical Distribution Maintenance Procedures 4

The Contractor shall complete the following tasks in once annually in Option Year 2:

Inspect ventilated (indoors) type while de-energized

Remove enclosure covers and clean vent louvers and screens.

Clean insulators, core and windings. Use bottle of dry nitrogen with pressure regulator, hose and small nozzle to blow off dust. Restrict pressure brush to 30 psi max. Clean with soft bristle brush as required.

Interphase barriers should not touch winding.

Wedges and clamping rings. For proper clamping of windings. Tighten as required.

Inspect primary and secondary buses and conductors for tightness of connection.

Tighten as necessary.

Inspect porcelain insulators for chips, cracks, and water streaks.

Inspect insulation materials for surface tracking.

Inspect windings for damage to insulation, including overheating.

MEDIUM VOLTAGE SWITCHGEAR MAINTENANCE

The Contractor shall maintain medium voltage switchgear and conduct the following tasks annually:

- Inspect fronts of circuit breakers. Record number of operations.

- Inspect indicating lights, repair/replace as required.

- Inspect auxiliary devices, wiring and terminal blocks.

- Inspect space heaters.

- Inspect ventilation louvers should be open.

- Clean or replace filters on ventilating louvers.

- Inspect insulators and insulating materials. Clean as required.

- Inspect cable terminations. Observe stress cones for cleanliness and tracking.

- Inspect batteries. Fill if maintainable. Clean connections as required.

- Inspect for evidence of leaks or condensation. Stop leaks and correct sources of condensation.

The Contractor shall maintain medium voltage switchgear while de-energized and conduct the following tasks once annually in the Base Year and Option Year 3:

- Clean, inspect, tighten and adjust all components, structures and enclosures. Wire brush, prime paint, and finish paint rust spots.

- Inspect buses, splices, and bolts. Check bolts and tighten to manufacturer's recommended torque. If inaccessible, check insulation tape, boot or compound box over bus splices for heat deterioration due to loose bolts, etc.

- Inspect insulators and insulating materials. Clean and inspect for surface tracking.

- Inspect meters. Test for accuracy. Adjust, and repair, as necessary.

- Make functional test on controls, interlocks and closing power rectifiers. Adjust, repair or replace as necessary.

- Check fuse clips for adequate spring pressure. Check fuses for proper fuse rating.

Replace as necessary.

- Inspect cable terminations. Observe stress cones for tracking and cleanliness. Clean, repair or replace as required.

- Inspect batteries. Refill if maintainable. Replace as required.

TE 6.5 Electrical Distribution Maintenance Procedures 5

- Functionally trip breakers with relays. Inject test current into CT and relay circuits.

- Inspect for evidence of leaks or condensation.

The Contractor shall maintain medium voltage metal enclosed switches and conduct the following tasks annually:

Inspect components visible through inspection windows:

Switch contacts

Fuse clips and fuses

Insulators and insulating materials

Space heaters

Cable terminations. Observe stress cones and leakage sections annually for cleanliness and tracking. De-energize and clean as necessary.

Inspect the following:

Loading. Re-distribute loads if possible.

Cleanliness. Moderate amount of dry nonconductive dust not harmful. De-energize and clean as necessary.

Dryness. Evidence of condensation or water leaks. Correct water leaks or source of condensation.

Check for rodents and reptiles. Block openings into switchgear as necessary.

Overheating of parts. Discoloration and/or oxidation indicate possible problem. Use infrared scanning equipment. Switches should be under normal load while being scanned. Repair damaged parts as necessary.

Tracking on insulation surfaces. Make necessary repairs.

The Contractor shall inspect and maintain indoor air metal enclosed switches while de-energized and conduct the following tasks once annually in the Base Year and Option Year 3:

- Verify that no parts or the power or control circuitry are energized by "back feed" from alternative power or control sources. Completely clean inspect, tighten and adjust all components.

- Structure and enclosures. Wire brush and prime paint rust spots. Finish paint.

- Ventilating louvers and air filters. Clean or replace air filters as required.

- Buses, splices and bolts. Check bolts for manufacturer's recommended torque. Tighten as required.

- Insulators and insulating materials. Clean and inspect for surface tracking.

- Space heaters.

- Main switch blades and contacts. Use safety precautions if switch is stored energy type.

Lubricate.

- Arcing switch blades and contacts. Dress or replace if arc eroded.

- Arc huts or interrupter devices. Do not lubricate. Check for condition, alignment and proper operations.

- Switch operating mechanism and linkage. Adjust for adequate contact closure and over travel.

- Switch/fuse door and other interlocks. Make functional check for proper operation sequence.

- Switch disconnect studs and finger clusters (if switch is draw out type). Lubricate, unless manufacturer's instruction specify that they should not be lubricated.

- Cable terminations and connections for tightness and re tighten as required.

TE 6.5 Electrical Distribution Maintenance Procedures 6

- Meters. Check for accuracy and repair or recalibrate.

- Fuse clips and fuses. Check clips for adequate spring pressure, replace if necessary.

Check for proper fuse rating. Refuse if necessary.

- Grounding. Reground as required.

- Potential and control power transformers.

The Contractor shall inspect and maintain indoor air metal enclosed switches and conduct the

Special emphasis on evidence of condensation and water leaks. Rust spots on underside of metal roof indicative of condensate. Correct source if condensation.

Special emphasis on space heater operation.

Ventilating louvers and air filters for cleanliness. Clean or replace air filters as required.

Inspect components visible through inspection windows (if provided):

Switch contacts

Fuse clips and fuses

Insulators and insulating materials

Space heaters

Cable terminations. Observe stress cones and leakage sections annually for cleanliness and tracking. De-energize and clean as necessary.

Inspect conditions:

Cleanliness. Moderate amount of dry nonconductive dust not harmful. De-energize and clean as necessary.

Dryness. Evidence of condensation or water leaks. Correct water leaks or source of condensation.

Check for rodents and reptiles. Block openings into switchgear as necessary.

Overheating of parts. Discoloration and/or oxidation indicate possible problem. Use infrared scanning equipment. Switches should be under normal load while being scanned.

Tracking on insulation surfaces.

The Contractor shall inspect and maintain automatic transfer control equipment while de-energized and conduct the following tasks once annually in the Base Year and Option Year 3:

- Functionally test by placing selector switch in manual position and operating control switches to open and close associated circuit breakers. Remove breakers from service.

- Functionally test by placing selector switch in automatic position and simulating conditions that should cause controls to operate associated breakers, to effect transfer of power. Remove breakers from service.

The Contractor shall inspect and maintain protective overcurrent relays on medium voltage and low voltage switchgear and conduct the following tasks once annually in the Base Year, Option

Year 2 and Option Year 4:

- Brush or blow dust off top edge of relay cover and remove cover.

- Remove relay disconnect device or open relay trip circuit switch and then open supply circuit switches in relay case.

- Release locking mechanisms, withdraw relay from case, and place on workbench in clean area and adjacent to test equipment. Remove only one relay from service at a time. Clean mechanism with soft, long bristle brush and/or very light air pressure.

TE 6.5 Electrical Distribution Maintenance Procedures 7

Tighten all screws and nuts. Inspect for broken or defective connections.

- Repair or replace relays that do not pass tests required by the electrical code. Inspect and clean dust and iron filing clinging to magnet and in air gap which might restrict rotation of disk.

- Inspect for correct alignment of disk and proper clearance from mechanism, magnet, etc.

Realign as required.

- Using relay contact burnishing tool, burnish contact surfaces and inspect contacts for burning and pitting. Replace contacts if burned or pitted. Inspect disk restraint spring for proper shape, tension, and possible damage from overheating. Adjust or replace spring as required.

- Record "as found" time lever setting on relay test long and temporarily set time lever adjustment on position "10". Turn disk with thumb until relay contacts closed. Release disk and allow it to reset again to "full open" stop device. Watch disk movement to detect if disk slows down or stops before contact bracket rests against the "full open" stop device. If so, make necessary adjustments, repairs, or replacement. Reset time lever to "as found" position. Check current top plug for correct position and tightness. If relay is of the type that is not draw out then disconnect relay wiring from switchboard prior to performing relay calibration and tests.

- Use a relay test set and follow manufacturer's instructions for test set in testing and calibrating relays. Select test points from applicable coordination or instruction sheets and calculate current or voltage to be applied to relay operating coil. Adjust set to apply proper values of test current and/or voltage.

- Test relay pickup point by applying test set voltage or current at which disk begins to run very slowly. After disk begins to turn slowly, lower test current or voltage slightly and check to ensure disk stops turning rests.

- Connect desired relay contact to timer circuit of test set. Adjust test set for current and/or voltage specified to test time contacts of relay. Push "initiate" button on test set and check actual time required for relay time contacts to close.

- If relay is equipped with instantaneous current attachment, adjust test set for current and/or voltage specified for testing same. Apply and check accurate timer for time required for instantaneous contacts to close. Adjust instantaneous contacts to close at current values specified. Test seal in contacts for closing at specified values.

- Check target flags for proper operation each time relay contacts close. Leave all targets in "dropped" position. Reset target flags and check that moderate vibration does not cause a false operation.

- Record "as found" and "as left" settings: Test current values and operating results; and maintenance and corrective action taken.

- Clean and inspect interior of relay case located in switchgear. Clean glass or plastic window in relay cover and check target reset mechanism for free movement.

- Insert relay into its case in switchgear and secure locking devices. Insert connection device or close switches inside relay case. Observe that disk does not begin to rotate.

If it does, remove connection device before contacts close and trip breaker, investigate reason, and make necessary correction.

- Replace relay cover and secure fastenings. Operate target test mechanism to determine that targets reset properly. The same general procedures for non-drawout type induction disk relays apply as for drawout types, except that relays cannot be easily removed from their cases and switchgear. A test receptacle is usually provided in the

TE 6.5 Electrical Distribution Maintenance Procedures 8 switchgear adjacent to each relay to facilitate testing. A suitable isolating jack is connected to the relay test set and inserted into the test receptacle. This disconnects the relay contacts from the breaker trip circuit in the switchgear and connects the test set current and/or potential leads to the proper operating coils in the relay.

The Contractor shall inspect and maintain other relays such as reclosing, synchronizing, and directional power relays on medium voltage and low voltage switchgear IAW manufacturer's instructions for maintenance and calibration.

MEDIUM VOLTAGE BREAKER MAINTENANCE

The Contractor shall inspect and maintain oil immersed drawout type medium voltage circuit breakers while de-energized and conduct the following tasks annually:

- Main contacts for pitting, spring pressure, overheating, alignment, overtravel or wipe.

Adjust or replace accordingly.

- Arc quenching assemblies for alignment, overtravel or wipe and for arc erosion. Adjust or replace accordingly.

- Moving parts and linkages for freedom of movement.

- Tripping mechanism for freedom of movement and reliability to open breaker contacts.

- Interlocks and safety for functional test to prove proper operation.

- Primary disconnect finger cluster for proper adjustment and spring pressure. Lubricate, unless manufacturer's instructions specify that they should not be lubricated.

- Secondary (control) disconnect contacts for alignment and spring pressure. Lubricate, unless manufacturer's instructions specify that they should not be lubricated.

- Closing and trip coils for general condition and evidence of overeating.

- Shunt trip device for freedom of movement. Test functionality.

- Undervoltage trip device for freedom of movement. Test functionality.

- Bushings for cracked and chipped porcelain. Condition of surfaces.

- Auxiliary contact for proper operation with closing and opening of breaker.

- Closing (x and y) relays (electrically operated breakers). Contact erosion. Dress or replace as required.

- Current transformers for general condition. Check nameplate ratio.

- Connection bolts. Check for tightness.

- Structure of frame for proper alignment and loose or broken parts.

- Fuses and mountings for general condition.

- Frame grounding device. Connect before and disconnect after primary fingers.

- Position indicators for proper operation.

- Auxiliary wiring for general condition and tightness of terminal screws.

- Arc for broken and missing parts and amount of metal spatter and burning on interior surfaces.

- Operation counter for proper operation.

- Insulators and insulating materials for cracks, breaks, and chips.

- Insulating oil.

The Contractor shall inspect, maintain and repair or replace, as necessary, medium voltage vacuum circuit breakers, Drawout type while withdrawn and de-energized and conduct the

TE 6.5 Electrical Distribution Maintenance Procedures 9

- Check contact erosion mark. Replace vacuum assembly if erosion mark is not visible.

- Open and isolate the breaker and detach the insulator coupler from the lever.

Atmosphere pressure will cause the lever to move. Check that an appreciable closing force has to be overcome when the lever is moved to the "open" position by hand, and that when the lever is released, it automatically returns to the "open" position with an audible sound as the contacts touch. Replace vacuum assembly if this test fails. After checking vacuum, reconnect the lever to the insulated coupler.

- Clean circuit breaker, especially post insulator and insulating couplers.

- Lubricate all bearings and sliding surfaces.

- Check all terminal screws. Tighten as required.

- Check all screw connections and locking devices on mechanism parts.

- Control cables and connections.

- Interlocks and safety devices. Test to prove operation.

- Primary disconnect finger clusters for proper adjustment and spring pressure.

- Spring charging motor and mechanism for proper operation.

- Position indicators for proper operation.

The Contractor shall inspect, maintain and repair or replace, as necessary, medium voltage air circuit breakers, drawout type while withdrawn and de-energized and conduct the following tasks annually:

- Remove arc chutes.

- Inspect main contacts are arcing contacts for pitting, spring pressure, overheating, alignment, overtravel or wipe. Adjust or replace accordingly.

- Test moving parts and linkages for freedom of movement.

- Inspect closing mechanism for quick and positive closing action.

- Inspect tripping mechanism for freedom of movement and reliability to open breaker contacts.

- Test interlocks and safety devices for proper operation.

- Inspect primary disconnect finger clusters for proper adjustment and spring pressure.

Lubricate, unless manufacturer's instruction specify that they should not be lubricated.

- Inspect secondary disconnect contacts for alignment and spring pressure. Lubricate, unless manufacturer indicates otherwise.

- Check closing and trip coils for general condition and evidence of overheating.

- Check spring charging motor and mechanism for proper operation and oil leaks from gear motor.

- Check shunt trip device for operation and freedom of movement.

- Check undervoltage trip device for operation and freedom of movement.

- Check auxiliary contact for proper operation with closing and opening of breaker.

- Check connection bolts for tightness.

- Check structure or frame for proper alignment and loose or broken parts.

- Check fuses and mountings for general condition and tightness.

- Check frame grounding device so that it connects before and disconnects after primary fingers.

- Check position indicators for proper operation.

- Check auxiliary wiring for general condition and tightness of terminal screws.

TE 6.5 Electrical Distribution Maintenance Procedures 10

- Check arc chutes for broken parts, missing arc splitters, and amount of metal splatter and burning in interior surfaces. Snuffer screens must be clean.

- Record number of operations on operation counter.

- Check insulators and insulating material for cracks, breaks, corrosion, tracking, and overheating.

- After above maintenance and testing has been satisfactorily completed, install electrically operated breaker in proper switchgear cell and rack it into the "TEST" position. Operation closing control devices to assure that beaker closed and latches without trip free operations. Operate trip control devices to assure that breaker trips open in a reliable manner. Functionally test all electrical interlock and safety devices.