Motor interlock start-stop issue
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There is a motor that requires control both remotely and locally; the DCS system uses separate sets of control cables to send signals to the motor control cabinet for starting and stopping the pump. When the motor is stopped locally (using a self-resetting button), will the DCS system accidentally start the stopped motor remotely due to misoperation? (In normal circumstances, the DCS sends start/stop signals to the motor via relays; that is, even after local shutdown, the relay that enables starting the motor remains energized.) Aside from installing a self-holding emergency stop switch in the electrical control cabinet to prevent the DCS from automatically starting the motor remotely, are there any other methods to achieve this?
At the site, operate the column-mounted local/remote control selector switch to determine whether control shall be remote or local.
The start and stop signals generated by the DCS system are matched according to the electrical schematic diagrams; generally, pulse signals lasting 3 to 5 seconds are sent, and after that time the relay loses power
There will always be a switch knob. You don’t have to worry. If a design institute can’t even think of this, then what’s the point of existing?
The electrical engineering field includes on-site operation columns, with both local and remote modes available. When it's local time, remote doesn't work.
The DCS system may automatically restart a stopped motor remotely due to improper operation, but there’s no need to worry about accidental startups. It prevents the motor from being started locally or remotely via DCS; only by moving the drawer to the testing position or maintenance position can it cease to function as a hot standby unit. It is very troublesome to have to request power from the electrical department before starting the unit.