Glossary, s - z – Watlow Series 922 User Manual

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WATLOW Series 922 User's Manual

Appendix

Glossary, S - Z

SYSTEM:

One of three main level operating parameters. From the
SYSTEM menu, you can generate a non-ramping set point
(fixed), manipulate Events 1 through 8, clear error codes and
latching alarms, and monitor Channel 2's actual temperature
and the external input.

Switching

In ON/OFF controls, the temperature change necessary to

sensitivity:

change the output form full ON to full OFF (3

F in the

Series 922.)

Thermal System:

A regulated environment consisting of a heat source, heat
transfer medium, sensing device and a process variable control
instrument.

Thermocouple:

Temperature sensing device that is constructed of two dissimi-
lar metals wherein a measurable, predictable voltage is
generated corresponding to temperature.

Thermocouple break

Fail-safe operation that assures output shutdown upon an open

protection:

thermocouple condition.

Three mode
control:

Proportioning control with reset and rate.

TI:

Represents the Real Time hours and minutes of the Series
922's system.

Time proportioning
control:

Action which varies the amount of ON and OFF time when
"close" to the set point, i.e., in the proportional band. This
variance is proportional to the difference between the set point
and the actual process temperature. In other words, the
amount of time the output relay is energized depends on the
system temperature.

Triac:

Solid state switching device.

WAITFOR:

One of six step types under the PROGRAM menu of the Series
922 that can be programmed to wait for a specific amount of
time, or a process value.

Warm start:

Start-up condition where all program information is remem-
bered by the instrument's memory backup protection.

WE:

Represents the state that the Series 922 will wait for, in the
program, for the remote event input to be present.

WHR:

The hour that the system will wait for relative to when the step
began. This is not a measure of time-of-day.

WMN:

Represents the minutes that the system will wait for relative to
when the step began. This is not a measure of time-of-day.

W1/W2:

Temperature that the system will compare against the process
variable of Channel 1 or Channel 2, and wait for, before
proceeding to the next step.

Zero switching:

Action which provides output switching only at the zero voltage
crossing points of the AC line.