ifm electronic is launching DL series level control relays that are said to make it much easier to control levels when monitoring signals from one or two sensors. Two models are offered, the DL0201 and DL0203, both of which are slim, rail-mount units than can run from a standard industrial or domestic mains AC supply and provide DC for connected sensors.
The DL0201 evaluation unit uses one sensor installed at the height of the level to be monitored. When this level has been reached, the DL0201 relay switches for an adjustable period of time (two potentiometers provided for 0-60 seconds ON and OFF delay). One application would be to detect a low level, then simply switch on a pump for a preset time to refill the vessel. Alternatively, if monitoring a high level, the DL0201 would shut a valve to stop further filling. An enable input is also provided so that, for example, a leakage sensor could override the relay.
The DL0203, on the other hand, is designed to take inputs from two level sensors so the output toggles between HIGH and LOW to keep a vessel topped up, with a delay possible to smooth fluctuations in the signal.
ifm electronic offers many suitable level sensors using a variety of technologies (including capacitive, guided wave radar and optical) so there will be a suitable level sensor available for most applications.
Follow the link for more information about level control relays from ifm electronic.