Xylem 378 TEMPERATURE CONTROLLER - Manual (Page 6)

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IV) Wiring diagram
a) Connect the AC line to the rear of the instrument. The model 378 can be used
with 115/230 VAC 50/60Hz, refer to drawing 4.
b) Connect the two thermocouple leads to the rear of the instrument .Be sure to
observe the correct polarity of the thermocouple leads. Refer to drawing 4.
V) Analog voltage output
a) The analog voltage output can be used to interface with instruments such as
recorder, printer, remote indicator, 4 to 20 mA converter, etc.
b) The following rules must be observed in order to avoid reading inaccuracies or
possible damage to the instrument.
1. If grounded or naked thermocouple is used, the interface device's circuit
common mustn't be connected to earth ground.
2. The input impedance of the interface device must be greater than 10 K
Ohms.
3. Be sure that the AC line voltage is never connected to the analog output.
VI) Controller action
a) The Model 378 is a single set point Proportional/On-off controller. The
proportional bandwidth is adjustable from On-off to 100°C or 100°F. with built-in
hysteresis. The cycle time is factory set to 20-second ± 3 seconds. Refer to
drawing 6 (Page 8) for proportional controller timing.