E-Stop Push-Button Implementation ???
E-Stop Push-Button Implementation ???
(OP)
Hello Everyone,
I wanted to get some direction or possible opinions regarding the electrical implementation of "E-Stop" push-buttons used in process related systems (for example a pump that is performing process "X" which is being driven by a medium voltage motor fed from a MV controller). In this case the process is being controlled and monitored by a local PLC--–start and stop commands from the PLC are wired directly to MV controller open and close circuits. In the case of an emergency you would want to wire contacts from the E-Stop push button directly to the MV controller trip circuit AND to the PLC (the PLC can then issue a back-up stop command for example)--right? Are there any codes or standards that would dictate proper implementation of E-Stop circuits that would be related to a process "X"? Or is the philosophy more of an industry best practice issue that is not really governed by codes and standards?
Thanks guys....
I wanted to get some direction or possible opinions regarding the electrical implementation of "E-Stop" push-buttons used in process related systems (for example a pump that is performing process "X" which is being driven by a medium voltage motor fed from a MV controller). In this case the process is being controlled and monitored by a local PLC--–start and stop commands from the PLC are wired directly to MV controller open and close circuits. In the case of an emergency you would want to wire contacts from the E-Stop push button directly to the MV controller trip circuit AND to the PLC (the PLC can then issue a back-up stop command for example)--right? Are there any codes or standards that would dictate proper implementation of E-Stop circuits that would be related to a process "X"? Or is the philosophy more of an industry best practice issue that is not really governed by codes and standards?
Thanks guys....






RE: E-Stop Push-Button Implementation ???
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RE: E-Stop Push-Button Implementation ???
For process control you might want to consider API RP 540. It is neither a Code nor Standard but it is an ANSI sanctioned recommended practice. ISA also has several documents that address the issue.
RE: E-Stop Push-Button Implementation ???
The emergency stop pushbutton SHALL be DIRECTLY wired in series to the coil of the motor control within the medium voltage controlgear such that it will simultaneously dropped all the contactor contacts INSTANTLY, and override all the command from the solid state devices, e.g. DCS or PLC.
NEC NFPA 70 mandated the motor local control station STOP / START pushbutton must be directly wired in series with the coil of the motor starter.
In my experience, I have seen medium voltage motors that have been damage because thay are hardwired directly to the DCS or PLC which has corrupted programs/software, and wrong configurations.