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CLASSIC 800 Product Manual
Setup & Operation
Failsafe Relay Configurations
The term “Fail-safe” refers to a method of wiring and programming control instrumentation commonly used in
hazardous locations/applications.
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In a “Fail-safe” application the CLASSIC 800 switch/transmitter is wired and programmed so that the
output relay is energized in normal process operating condition.
•
Thus, in the event of a power failure, cable break, self-test failure, or other loss of electrical power, the
contact is “opened”, the relay is de-energized and an alarm will result.
A common “Fail-safe” setup for
NO FLOW CONDITION, PUMP PROTECTION:
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Connect the relay contact wires to Normally Open (R1NO, R1CM)
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Program the relay(s) to energize above set point.
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Depending on application and setup of the switch/transmitter, the relay contact(s) will OPEN (de-
energize) when:
a. The Thermal Signal decreases due to a decrease or loss of flow/level.
b. Power is lost to the switch/transmitter as described above.
