Ultrasonic level gauge for interlocking the start and stop of pumps
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I would like to ask the experts here: there is no PLC or DCS on site, but I want to use an ultrasonic level gauge to interlock the start and stop of a pump – the pump should stop automatically when the liquid level is low and start automatically when the level is high. Additionally, an audible and visual alarm is required, with alerts issued when the liquid level is too high. The ultrasonic level gauge provides a 4-20mA HART output and operates on 24V power. If a PLC or DCS cannot be purchased externally, can these functions be achieved using a digital display and relays?
It is recommended to add a secondary meter; a small one will suffice. It’s okay without a dedicated temperature controller for the secondary meter… it costs little, and no relay is needed either.
Can I understand the secondary meter you mentioned as a digital display meter? This kind of heating controller probably won’t work
It’s a digital display secondary meter, with upper and lower limit alarms. If the temperature controller has a 4-20mA input and a relay output, it can be used just fine; there’s no problem at all.
Of course, secondary instruments can be used as controllers, but ultrasonic level gauges are not very reliable for control purposes
It’s completely possible; just use the output of the alarm contact on the secondary strap
The digital display has several sets of contacts similar to those of a relay output.