ATTACHMENT C

Public Works Department

Automatic Transfer Switch PM Checklist

Automatic Transfer Switches (ATS): shall be subjected to a maintenance and testing program that includes all of the following operations:

• Infrared/thermal image scan

• Inspection of conductor terminations, ATS’s control components, and electrical conductors.

• Inspection or testing for evidence of overheating and excessive contact erosion

• Removal of dust and dirt.

• Inspect for water, moisture, and critters.

• Replacement of contacts when required.

ATS and Paralleling Gear: shall be subject to inspection, testing, and maintenance program that includes all of the following operations:

1. Perform an infrared/ thermal image scan of ATS before any work is performed

2. Identify and note any issues that were identified during the infrared/ thermal scan to be addressed during the PM.

3. De-energize the ATS (if ATS is equipped with an isolation bypass feature, do not need to be de-energized)

4. Inspect ATS Conductor Connections and ATS’s Mechanical Switch, and it’s contact points. Repair any connections that show evidence of failure, erosion, pitting, corrosion, and overheating.

a. Inspect all conductor terminations for evidence of hot spots at termination points, and look for evidence of termination corrosion, and loose connections. If conductors have crimped ring terminals- inspect for fit and/ or lose crimped points, corrosion, and evidence of failure at the crimped connection.

b. Inspect all conductors for evidence of hot spots on conductors for overheating and/ or failing conductor insulation

c. Inspect for evidence of hot spots at mechanical connections of the ATS check/verify contact points for evidence of pitting and/or erosion

5. Remove the arc chutes and pole covers. Consult the manufacturer’s information for proper procedure. This step will allow visual inspection of the main and arcing contacts…. Inspect all main arcing contacts for excessive erosion and/or pitting.

Arcing contacts are intended to be sacrificial by nature. They take the brunt of the energy when making or breaking the load. Careful attention should be paid to these contacts.

6. Inspect ATS and Cabinet for moisture or signs of Water, moisture, critters, and previous wetness or dripping.

7. Test and recalibrate all AC sensing and time-delay functions in the switchgear.

Depending on the manufacturer, the steps required will vary.

8. Vacuum the accumulated dust from the switchgear and accessory panels. Never use air to blow out dirt. Subjecting the transfer switch mechanism to compressed air may have a detrimental effect by forcing dirt and debris into the switch mechanism.

9. Inspect all control relay contacts and wiring for excessive erosion and discoloration due to excessive heat. Inspect all control wiring, connection points, and relays for discoloration, and evidence of rodent and insect damage (chewed wires, excessive spider webs, reptiles, and nests)

10. Manually operate the main contactor for transfer movement to check proper contact alignment, deflection, and sliding/ wiping action. (The sliding action is performed after two opposing contacts make contact. This wiping action helps to reduce the influence of film or dust that collects on the surface of contacts).

11. Check all cable and control wire connections to the transfer switch controller, sensing panels, and other system components. Tighten if necessary.

12. Inspect all electrical conductors and wiring connections and re-torque connections if needed. Inspect conductors for cuts or damage to the insulation. If conductors have splice points-inspect splices for snugness, inspect insulating material that is protecting splices from cuts, missing tape, discoloration, moisture and evidence of failure, and repair if necessary.

13. Clean ATS Cabinet and its components from grime with an approved non-conductive solvent. Consult the original equipment manufacturer (OEM) for a recommendation

14. Repair and/or replace defective equipment.

15. Post-Repair/Installation Functional Testing: A full system retest (e.g., simulate power failure post-repair) to verify compliance with transfer times (e.g., <10 seconds for Level 1).

16. Scheduled Maintenance Program label, to be installed one per facility at the electrical service. Include the date completed and a legible name and signature from the electrician completing the maintenance.

17. Comment on overall condition of service and enclosures.