User guide

Watlow Series 97 Appendix ■ A.17
time proportioning control — A method of controlling power by varying the
on/off duty cycle of an output. This variance is proportional to the difference
between the set point and the actual process temperature.
transmitter — A device that transmits temperature data from either a
thermocouple or a resistance temperature detector (RTD) by way of a two-wire
loop. The loop has an external power supply. The transmitter acts as a variable
resistor with respect to its input signal. Transmitters are desirable when long
lead or extension wires produce unacceptable signal degradation.
WatLink — A Watlow software application for configuring and communication
with Watlow controllers via a EIA-485 network and a Microsoft Windows-
compatible personal computer.
zero cross — Action that provides output switching only at or near the zero-
voltage crossing points of the ac sine wave. See burst fire.
zero switching — See zero cross.