Xylem 378 TEMPERATURE CONTROLLER - Manual (Page 8)

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d) The process temperature may settle at any value within the proportional band.
e) Adjust the Reset control clockwise if the process temperature is less than the set
temperature. The Reset control is disengaged for On/off control.
f) Repeat Step 5 (e) until the process temperature is equal to the set temperature.
IX) Relay and front panel led format
a) Connect the heater circuit to the N.O. and COM terminals of the relay. Make sure
that the load doesn't exceed the rating of the relay, 8 A at 115VAC and 4A at
230VAC. The relay rating is for resistive load only.
b) The LED on the front panel will be On when the relay is energized .Power is
delivered to the heater through the N.O. and COM terminals of the relay.
X) Thermocouple burn out protection
a) The thermocouple burn out normally would result in an open circuit. The meter
will be roll up scale, exceeding the set point and de-energized the relay. Power to
the heater will be cut off.