In emergency power systems, auto transfer switches (ATS) are used to offer a continuous source of strength for lights and different critical hundreds by way of transferring from the ordinary supply of strength to an emergency source of energy in the occasion that the regular supply voltage falls underneath preset limits. This guide gives information on the overall inspection, operation and protection tactics of guide and automatic switch switches.

Manual Contents for auto transfer switch testing and maintenance are

  • Analysis for Visual & Mechanical Transfer Switch
  • Review of predominant Contacts & Bolted Connection supervision
  • Standard Transfer Operation
  • Inspection on Insulation Resistance
  • Evaluation for Operational Timing and Automatic Transfer
  • Trial run on Functional Procedure for Automatic Transfer Switch

Transfer Switch Visual and Mechanical Maneuver

To find out the appropriate system ratings and connections  compare the equipment data with the project design and specifications initially. Authentication of the phase rotation and integrated operation are to be done as per the application requirement. Scrutinize the environmental condition of the transfer switch for approval. Installation of the switch covers are should be taken care.

Review that the cabled network and the phase rotation power for both sources lookalike. To check the collapse or badly shabby parts, mechanical stability analysis to be done.

Sustain a clear and free of blockage transfer switch. To avoid any accumulation of dust, dirt, or moisture in the switch inspection must be done cleaned by vacuuming or wiping with a dry cloth or soft brush. Moving current-carrying element and the sliding surfaces are to be examined for the appropriate lubrication. Standard transfer caution should be attached apparently. Invest engine start connections of all control wires to avert wreck.

Major Bolted Connections

The auto transfer switch barriers or arc chutes condition of the contacts are analysed and eliminated. Renewment is done if the contacts are drained and if material deposits are found are removed with a clean cloth. Verification of contact/pole-resistance executed. Consider standards that depart from the allied switches or beside poles by 50 percent of the lowest value, if manufacturer’s proclaimed info is not available. Using either of the method survey bolted electrical connections for high resistance

  • Low-resistance ohmmeter
  • Calibrated torque-wrench method
  • Thermographic survey

ATS Standard Transfer Performance

For maintenance purposes in the transfer switch a manual operator handle is provided, must be checked and be de-energized before it is operated electrically. Operate the transfer switch smoothly without binding between the Normal and Emergency positions.

ATS Analysis of Insulation Resistance

Investigation of insulation-resistance performed on all control wiring with respect to ground. Insulation-resistance values of control wiring should not be less than two mega ohms. The previously obtained results can be compared for maintenance, but not less than two mega ohms.

ATS Automatic Transfer Tests

Automatic transfer tests execution:

  1. Pretend the loss of normal power.
  2. Counterfeit the power wastage.
  3. Single-phase conditions forms fabrication.

ATS Operational Timing Evaluation

Check up on the correct operational timing of the following purpose:

  1. Source voltage & frequency relays.
  2. Engine kick off progression.
  3. Automatic transfer operation.
  4. Switch function Limitation.
  5. Simultaneous Time delay & power restoration.
  6. Engine shutdown and cool down component.


ATS Peripheral Visual Review

Repair the unit if there any sign of wreck or break in the line.

ATS Moisture Sign Examination

Not ever try to operate a wet or damp transfer switch since the accumulated moisture from high humidity contact from a foreign source can lead to deliberate hazard. During operation excessive heat generated by automatic transfer switch lead to discoloration, abnormality and ruin to contacts.

ATS Dust Evacuation

Vacuum can be used to evacuate dust and debris, as it impede the connection and reduce the effectiveness of the ATS. Clean the transfer switch using an approved industrial solvent. Be sure of any incorporated foreign materials or filth are totally removed.

Written by Praveen

Auto Transfer Switch