A Switch Fuse Unit (SFU) panel checklist ensures that the unit is designed, installed, and commissioned correctly to provide safe electrical isolation and protection. The checklist covers mechanical, electrical, and safety aspects, primarily focusing on the integration of fuses within a switch for low-voltage power distribution
Here is a comprehensive checklist for an SFU panel:
1. Physical and Mechanical Inspection (Pre-installation)
- Enclosure Quality: Check that the panel enclosure is powder-coated, rugged, and free from dents or scratches.
- IP Protection Rating: Verify the IP rating (e.g., IP44 or higher for outdoor) is appropriate for the installation environment.
- Dimension Check: Ensure dimensions (height, width, depth) match the approved drawing.
- Door Interlock: Ensure the SFU handle has an auto-restorable door interlock (panel cannot be opened while in the ‘ON’ position).
- Cable Entrance: Check that cable entries are on the correct side (top/bottom) and have gland plates provided.
2. Electrical Components and Assembly
- SFU Rating: Verify that the SFU ampere rating (e.g., 63A, 800A) matches the design specifications.
- HRC Fuse Links: Verify that HRC fuses of the correct rating and capacity are installed.
- Busbar Integrity: Inspect busbar size, quality, and torque marks on joints.
- Insulation: Ensure proper separation between phases and that Hylem sheets are used if required.
- Indicating Lamps: Test ON/OFF indicator lamps.
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3. Cabling and Earthing
- Termination: Ensure cable lugs are properly crimped (three-time crimp method) and tightened.
- Cable Glanding: Verify all cables are properly glaned and the armor is grounded.
- Earthing Connections: Ensure double earthing is provided to the panel body and doors.
- Clearance: Check that live parts have appropriate phase-to-phase and phase-to-earth clearance.
4. Testing and Commissioning
- Insulation Resistance (IR) Test: Conduct a Megger test (Panel to Earth, Phase to Phase).
- Operation Test: Ensure the SFU handle operates smoothly and the mechanism is not sluggish.
- Functional Test: Verify the door interlock mechanism functions correctly.
- HV Test: Perform High Voltage testing to check insulation integrity.
5. Safety and Documentation
- Safety Signs: Ensure danger boards and warning labels are clearly displayed.
- Labeling: All circuits, fuses, and feeders must be properly labeled.
- Drawings: Ensure as-built drawings are available.
This checklist is based on general electrical panel inspection standards, including LT Panel, MDB, and specifically SFU/Fuse Switch units
