How does DCS control the start and stop of frequency converters and pumps?
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I currently have a pump that is controlled by an inverter; to start or stop the pump, I use the start/stop buttons on the inverter. However, the process requirements specify that it should be possible to start and stop the pump from the control room, as well as to adjust its speed via the inverter. How can this be achieved? How should the control system be configured, and what should the interface look like? Please explain in detail, urgently! ! !
Consult the frequency converter’s user manual to introduce the remote control contacts into the DCS system (the frequency converter may also require relevant settings to enable remote control)； Remote frequency conversion control can be achieved using the AO function of a DCS system; configure a remote control point HC (ranging from 0 to 100%, with a 4–20 mA signal output). Inverters generally have the capability to accept external analog signals for control purposes. Consult the manual, introduce this control point, and make the corresponding settings on the inverter ； Add start/stop buttons and HC remote control points to the flowchart screen, and configure the connections. If necessary, a speed display can also be added (most frequency converters also provide an analog output for this signal)
If it is merely a start signal, adding two D points to control starting and stopping will suffice; the frequency converter needs to be configured, based on my personal understanding.
Most frequency converters have contacts, which makes control very convenient; by looking at the terminal diagram of the frequency converter, one can generally figure out how to use it
A relay will do the trick
Generally, DCS systems come equipped with corresponding variable-frequency motor modules! The AO receives the analog signal from the inverter as input to perform frequency conversion. At 0%, the pump stops!
It’s possible to do this. There are basically two methods: 1. Use the DCS to provide a DO signal as the start/stop signal, which is then connected via wires to the terminals of the frequency converter; the frequency converter is set up to use this terminal as the start signal, while an AO signal is used as the frequency control signal – for example, a 4–20 mA signal is sent to the frequency converter’s terminals, and the frequency converter is configured to use this signal as the frequency control source. 2. Utilize communication protocols such as 485; a serial server on the DCS is used to communicate with the frequency converter, and values are written to the corresponding address points on the frequency converter. Once the frequency converter has its start signal and frequency control signal sources set, DCS control can be implemented. If it seems too complicated, simply call the application engineering department of the frequency converter manufacturer