Prosedur Pagsulay sa Low-Voltage Electrical Room: Pag-asekuro sa Estable nga Operasyon sa Sistema sa Kuryente

Pagsulay sa Main ug Control Circuits sa Low-Voltage Switchgear (Pagtangtang sa Dust); Pagsulay ug Maintenance sa Isolators, Circuit Breakers, Contactors, ug Relays

I. Pagpreparar ug Standards Bago ang Maintenance

• Pagpreparar Bago ang Maintenance:

• (1) Working Conditions: Scheduled shutdown ug power disconnection.

• (2) Tools ug Instruments:Measuring instruments ug tools including: insulation resistance tester (megger), clamp meter, multimeter, combination wrenches, voltage tester, electrician pliers, screwdrivers, utility knife, etc.

• (3) Personal Protective Equipment (PPE):Safety helmet, insulating mat, insulating shoes, grounding wires, face mask.

• (4) Materials ug Spare Parts:Conductive grease, sandpaper, clean cloth, wires, blower, replacement components.

• (5) Safety ug Technical Measures:Complete ug issue work permits ug power on/off permits; conduct work content briefing; verify implementation of safety measures; review ug confirm safety precautions.

• Coordination: Shut down equipment ug disconnect power. Verify absence of voltage ug hang "Under Maintenance" signs. For busbar maintenance, install grounding wires, set up warning signs, ug assign a dedicated supervisor during work.

II. Internal Maintenance sa Low-Voltage Switchgear

Bago magsugod sa maintenance, buksan ang cabinet door ug gamit ang blower para tangtangon ang dust nga nakalubog sa loob sa cabinet.

III. Maintenance Standards para sa Main ug Control Circuits

• Inspect busbars ug main terminal connections for discoloration or looseness. Ensure no deformation or bending, ug that electrical clearances meet standards (phase-to-phase >20mm at 380V, phase-to-enclosure >100mm).

• Clean cable trenches—ensure no standing water or debris; supports should be intact, secure, ug free from corrosion; covers must be complete; rodent-proofing at exits leading outdoors must be effective.

• Control circuit wiring must be correct, neat, tight, clearly labeled; fuse connections must show no discoloration or looseness.

• Panel indicators must be intact ug reliable. Use a multimeter to test selector switches ug push buttons—contact resistance should be less than 0.5Ω. Switches ug buttons must operate smoothly without sticking.

• Inspect primary contacts of drawer-type units for burn marks; spring pressure should be even ug contact good. Secondary contacts’ metal spring contacts must not be bent or deformed. Measure contact resistance between secondary plug ug socket—must be less than 0.5Ω.

IV. Isolator Switch Maintenance Standards

• Operating handle should move smoothly ug reliably; linkage base must show no burn or discharge marks; open/closed positions must be fully engaged; set screws, pins, ug rods must be intact ug secure.

• Insertion depth of moving ug fixed contacts must be no less than 2/3 of the blade width; contact area must cover at least 75% of the contact clip.

• Moving ug fixed contact surfaces must be free from burning; contact must be tight. If oxidation is present, clean the oxidized areas ug apply a thin layer of Vaseline or conductive grease to prevent further oxidation.

• Contact pressure: 45–80N for switches below 200A; 75–100N for 250–400A isolators; 150–220N for 500A ug above. Adjust if out of range.

V. Air Circuit Breaker Maintenance Standards

Open the breaker housing ug check incoming/outgoing lines for discoloration or looseness. Main contacts must show no burn marks. Operate the breaker twice—moving ug fixed contacts must engage tightly with even pressure. Measure resistance with a multimeter—should be less than 0.2Ω. Arc chutes must be intact ug undamaged.

After reassembly, the operating handle must move freely without obstruction. Pressing the test button should cause immediate tripping.

VI. AC Contactor Maintenance Standards

• The short-circuit ring on the electromagnetic core must be securely fastened. When energized, the contactor should operate silently. The core surface must be clean ug free from oil; coil insulation must be undamaged; coil surface must show no discoloration or overheating.

• Remove the arc chute ug inspect main contacts—they must make tight contact, show no burns, operate smoothly without sticking, ug have even pressure. Contact gap must be within acceptable limits.

• Components inside the arc chute must be intact; smoke residue must be cleaned. Linkage mechanism must have good insulation, with no deformation, displacement, or loosening.

• Auxiliary contacts must operate smoothly without sticking; normally open ug normally closed contacts must make good contact with no arcing damage.

VII. Relay Maintenance Standards

• Inspect relay appearance—no contact burn marks. Energize the coil at rated voltage—the relay should pull in smoothly without noise or vibration. In the closed position, use a multimeter to confirm all contacts conduct properly.

• For thermal relays, verify setting values are appropriate for the connected equipment. Press the test button ug use a multimeter to confirm auxiliary contact operation is normal.

• Thermal relays must be calibrated ug operate sensitively ug reliably.

• For electromagnetic current relays, error between operating value ug scale value must not exceed ±5%.

• VIII. Post-Maintenance Measurements ug Tests

• After maintenance, count tools ug ensure no tools or debris remain inside the cabinet. Measure main circuit insulation resistance: using a 500V megger, readings must be ≥5MΩ for 380V circuits, ug ≥0.5MΩ for 36V control circuits. Insulation resistance between breakers, busbars, ground, ug phases must exceed 10MΩ.

• Remove "Under Maintenance" signs, remove grounding wires, close ug lock cabinet doors. Set switch to "Test" position, close the breaker to energize, ug perform no-load open/close tests. Operate open/close functions twice—switch must operate smoothly ug reliably without sticking; indicators must function correctly.

• Clean the work area thoroughly. Complete maintenance records—collect documentation, ug fully record any replaced parts or adjusted components in the equipment logbook. Conclude maintenance ug notify operators to test run the equipment.

• For equipment with replaced control components, measure three-phase operating current for balance ug verify normal three-phase voltage. Record results. Observe operation for at least 0.5 hours. Only release for service after confirmation ug signature by all three parties (contractor, supervisor, ug user).