Intrinsically Safe Relay (ISR) The Intrinsically Safe Relay ISR provides a safe and reliable method of load control when interfaced with a contact closure in a hazardous location. When the control switch input is closed between pins 1 and 8, the output relay becomes energized, and the LED is illuminated. When the control switch input is open, the output relay is de-energized, and the LED is turned off. It provides intrinsically safe circuits for use in Class I, Groups A, B, C, D Class II, Groups E, F, G and Class III - Hazardous Locations. The socket is included with the Intrinsically Safe Relay.
Level Probe Relay The Level Probe Relay senses liquid level and provides a relay output for controlling a pump or level alarm. The unit has two inputs, an ON and an OFF, for connection to two electrodes of a conductance probe. All setup is easily done using the DIP switches on the unit.
When used for a level alarm the ON and OFF inputs may be connected to the same electrode on the probe, or the ON input may be used by itself. When used for pump control the ON and OFF inputs are typically connected to two different level probe electrodes to provide a latching function.
The unit has two pump control modes, Pump Down (empty a tank) and Pump Up (fill a tank) (see table below). When in the Pump Down mode and both inputs detect liquid, the unit energizes the relay and keeps it energized until the level drops to the point where the OFF input no longer detects liquid. When in the Pump Up mode and both inputs detect no liquid, the unit energizes the relay and keeps it energized until the level rises to where the OFF input detects liquid.
The Sensitivity of the unit must be set for the type of liquid being detected (see the Dip Switch table). The unit provides a 10 second power up delay to prevent a pump from being turned on too soon after a power interruption. An adjustable ON Delay is provided for use as a lag pump delay. The adjustable OFF Delay is provided so that the unit may be used to provide timed off, backup pump control. (See the Dip Switch table for ON and OFF delay settings.)