Seeking everyone's help with the state feedback issue
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Regarding the issue of the motor not starting or stopping via the computer, as well as the DCS alarm problems: when the motor is under remote control and started/stopped through the DCS, if the motor stops suddenly or is stopped by personnel on-site, an alarm should be triggered on the DCS. I’m not sure whether Zhejiang University’s DCS system or Honeywell’s DCS systems can achieve this, and I’d like to know how to do it. Thank you all
Can the author’s intention be understood as this: the motor on site is set to local operation, allowing local control over its start and stop?； Switch to remote operation; DCS controls start and stop ； But no matter where the motor is controlled, as long as the motor stops running, an alarm appears on the DCS screen. I’m not sure if that’s what the original poster meant. If so, it’s simple – it’s just a matter of displaying a status.
This function should be easy to implement. If you use ordinary contactors to control starting and stopping, you just need to connect the auxiliary contacts of the contactors to the DCS. In the case of soft starters or frequency converters that have fault outputs, you connect those fault outputs to the DCS. As for implementing alarms or other functions, it depends on you; whether it’s a central control system or Honeywell, it’s definitely possible – there’s no problem with that!
It is not difficult for the building owner to implement this function: the local/remote signals as well as the start/stop signals of the motor can be sent to the DCS, and a simple check can be performed; if the motor is in remote control mode and at the same time it is in the stopped state, then an alarm should be issued.
Sure, one DO point can be used for remote shutdown, and one DI point can be used for operation indication
An alarm can be triggered as long as the operation/stopping status of the motor is fed back to the DCS system; if no such status feedback is available, the current signal can still be used for determination.
Do as the moderator suggests. Who is responsible for this project? The requirements you mentioned are the most basic ones for a project. What’s the use of an operation station if it can’t display the device status?
This post was last edited by jacky77576 on 2012-9-3 00:13. Does the original poster mean that when starting locally, the system only receives feedback status, and if the system does not issue a start command, it will result in a feedback error? When starting remotely, the startup command is provided by the system, and after receiving feedback on the start-up, the system operates normally without any errors. Then, under other abnormal conditions, the system should issue a warning indicating an error. This can be achieved in the following way: there is a toggle switch on the on-site control box, with three settings – local, stop, and remote. The status of these three gears must be connected to both the 220V electrical control circuit and the 24V DI channel, so that the system can also be aware of the gear status. When starting locally, the changeover switch is set to the local position, allowing the electrical local control circuit to take over while the remote control circuit is disconnected. At the same time, the system switches to local mode as well, with the feedback signal connected to the start input. In this way, starting and stopping occur simultaneously both at the site and through the program. When starting locally, the system does not generate any errors, and it is also possible to accurately monitor the feedback status. When switching to remote mode, the start signal does not need to be connected to a feedback circuit as in local mode; since the start signal is generated by the system at this time, it is sufficient to simply monitor the feedback signal. If the switch is suddenly moved to the stop position (the middle neutral position), the electrical control circuit is interrupted, and at the same time the neutral signal triggers an emergency stop in the system; both the system and the equipment on site come to a halt, without any error messages being generated. Errors are reported for other abnormal situations. I have never come across the two systems mentioned by the original poster, but the principle behind them should be the same, and such functions certainly exist. The key is to integrate the position status of the changeover switch into the system, while also coordinating it with the electrical control principles
It’s just a matter of adding a color change to the screen; I just did it here yesterday