We discuss about MCC / SWR Loop Checks Procedure. Loop checks involves DCS loop checks, VSD loop checks, PLC loop checks and Transmitter loop checks.
MCC / SWR Loop Checks Procedure
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Check the Power Transmitter linearity on each cubicle wherever applicable VSD commands i.e. AO/AI Shall be included, and the Testing requirements if no test position available.
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Check and verify the DCS configuration for applicable points.
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If ESD logic / interlocking are involved in applicable loop, by forcing the applicable ESD points on ladder logic, same procedure to be carried out for DCS logic.
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Remove the control power transformer primary and secondary fuses for applicable MCC/SWR units (check / confirm if MCC/SWR unit is on test position by electrical).
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Apply 120Vac power (external power from building outlet) on the secondary fuses load side to energize the control circuit.
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Apply the command from DCS / ESD Field for start, stop or trip as applicable.
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Verify the running / stop or trip status in DCS / Field / Sub Station as applicable.
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Check and verify the local / remote switch function if applicable.
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After completion of the applicable loop check, the fuses should be returned on the
control transformer. -
All the above mentioned steps can be carried out with removing the pad lock on the MCC/SWR unit breakers.
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Removal of the pad lock on the breakers required permission from Electrical Mechanical section.