APPLICATION NOTES Product/s: Radio Frequency Probes - RLP Subject:                              Wiring for High and Low Level Control

Sheet Number: AN-02160-01 Version: 300498-02 File: 20-03050 Electronics Products

Using 2 RLP probes to control the high and low liquid levels in a vessel. Should the liquid level fall below the
low level RLP sensing rod .... a pump or valve would activate. The pump or valve would stop .... only when the
level reaches the high level RLP sensing rod.
Please Note: The circuit below is diagrammatic and indicates no specifications. Each application for this circuit
will determine the specifications of each piece of hardware required to build such a circuit. The circuit below
incorporates protection against the failure of any of the hardware required to operate the External Control
Relay. The External Control Relay need only be a simple relay for most applications.
It is recommended that suitable suppression devices be fitted to any used relay contacts to reduce the contact
damage caused by Back EMF.
The relay operation mode on the RLP units should be set to (Normal Mode)