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Method Statement for Variable Frequency Drives VFD Testing and Commissioning

In one of our previous post we mentioned details about the variable frequency drives principle. Now this page provides you the method of testing and commissioning of VFD drives in simple steps. Remember before testing all installation and construction completion should be approved.

Power Connection Requirements: Megger the incoming and outgoing power cable & connections for Insulation check & short circuit. Please note that the power cables in the VFD’s terminals must be disconnected during this test or it may damage the VFD’s. Reconnect the cables and all power terminals shall be checked for tightness. All the power cables shall be supported well so that the stress is not on the terminals. All fuses and overloads shall be checked for correct sizes.

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Controls Connection Requirements: All control connection terminals shall be checked for tightness and continuity. The screens of the screened cables shall be checked for proper earthing. All terminations shall be cross checked with the drawing with respect to correct sizes and usage of accessories.

Insulation Resistance Test using 500V Megger: VFD Block Diagram

Check the tightness of connections. Clean all the supporting insulators. Isolate the cables on incoming and outgoing side. Apply a megger voltage of 500Volts DC between Phases ‘R’ to earth for 1 min with Phase ‘Y’,’B’ & ‘N’ shorted and earthed and record the values. Similarly continue the test and record the values for the other phases.

Pre-commissioning & Commissioning:

Check the incoming voltage & phase sequence before switching ‘ON’ the incomer. Check control supply and stop lock provision and operation. Check bypass starter operation with the motor disconnected. Check VFD’s operation with the motor disconnected, from the control keypad. Set parameters as required and record the parameters on approved formats and test sheets.

Check VFD’s operations from keypad after connecting the motor, also check motor’s direction or rotation. Check bypass starter operation with the motor connected, also check motor’s direction or rotation. Check external (remote) control of the VFD’s.

Complete all the T&C checklists and manufacturer forms to record the T&C data. Work Inspection Request shall be raised for Consultant and client inspection and sign off of testing and commissioning works.

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