Daily Maintenance Guidelines for SPD and MCB to Ensure Electrical System Safety

I. Daily Maintenance of SPD (Surge Protective Device)

1. Visual Inspection

   • Check for cracks, scorching, or discoloration on the casing; ensure terminals are free from oxidation or looseness.

   • Verify labels are legible (e.g., model, voltage rating, failure indicator).

2. Status Indicator

   • If equipped with an indicator light, ensure it displays normal status (typically green = functional, red = failed).

   • Replace immediately if the indicator is abnormal or extinguished.

3. Grounding Connection Check

   • Ensure the grounding wire is secure; grounding resistance ≤10Ω (≤4Ω for critical facilities).

   • Inspect for corrosion or breakage in the grounding conductor.

4. Performance Testing

   • Periodically measure let-through voltage and leakage current using a dedicated tester (replace if leakage current exceeds 1mA).

   • Inspect the SPD immediately after lightning strikes or major surge events.

5. Records and Replacement

   • Document inspection dates, test data, and replacement history.

   • Recommended service life: 5–8 years, or per manufacturer’s instructions.

Maintenance Cycle: Quarterly; additional inspections after thunderstorm seasons.

II. Daily Maintenance of MCB (Miniature Circuit Breaker)

1. Operational Test

   • Manually switch ON/OFF 3–5 times to confirm smooth mechanism operation without jamming.

   • Test trip function (via "TEST" button or simulated overload).

2. Terminal Inspection

   • Tighten input/output terminals to prevent overheating due to poor contact.

   • Check for insulation aging or damage on conductors.

3. Cleaning and Heat Dissipation

   • Remove surface dust with a dry cloth to prevent accumulation affecting heat dissipation or causing short circuits.

   • Ensure adequate ventilation in the installation environment.

4. Fault Analysis

   • Record trip frequency and causes (e.g., overload, short circuit); investigate circuit faults.

   • For frequent tripping, verify load compatibility (check rated current limits).

5. Arc Chamber Inspection

   • Inspect arc chute plates for integrity, absence of carbonization, or metal residue.

   • Replace the MCB if severe arcing traces are observed.

Maintenance Cycle: Biannually; reduce to quarterly for high-load or harsh environments.

III. Safety Precautions

1. De-energize and verify power is off before maintenance to prevent electric shock.

2. Use insulated tools; wear protective gloves/glasses.

3. Replace devices with identical specifications/models; avoid mixing types.

4. Only qualified electricians with certifications should perform operations.

   
   

IV. Common Issue Handling

• SPD Failure: Replace immediately to avoid equipment exposure to surge risks.

• MCB Fails to Reset: Check for short circuits or overloads; rectify faults before resetting.

• Abnormal Heating: Re-tighten terminals or replace with a higher-rated device.

Regular maintenance significantly reduces electrical failure risks and extends equipment lifespan. Address identified hazards promptly and document all

actions.