Omega WMS-T-AL - Manual (Page 3)

WMS-T-AL Dual Set Point Temperature Alarm
Introduction
The WMS-T-AL is a microprocessor-based dual set point Temperature Alarm packaged in a
NEMA 4X box with a transparent cover. It has been designed with two independently
controlled relays. The relays are used to control power to the users temperature sensitive
device(s) or to operate operator selected secondary alarms. The control module has a liquid
crystal digital display and push buttons for viewing and selection of the operating mode and
the alarm threshold values. The user can control three parameters for each alarm channel:
Threshold delay before the relay triggers after threshold temperature is crossed, and delay time
before the relay turns off after the temperature re-crosses the threshold . Each relay can be used
in either the normally open or the normally closed mode. A piezoelectric buzzer in the control
module can be activated to turn on when ever the alarm state is active.
General Description
The WMS-T-AL consists of two components a temperature sensor to measure temperature and
a control module.
TEMPERATURE SENSOR
The temperature sensing probe is based on a precision thermistor and is designed to measure
over a wide range of temperatures. The thermistor has a resistance value of 10,000 ohms at 25°C
and has a highly reproducible response curve. The sensor accuracy is ±1°F (±0.55°C). Resolution
is to 0.1°F (0.05°C). The measurement range is from -40°F (-40°C) to 160°F (60°C). The Alarm
range is from -40°F (-3°C) to 160°F (+3°C). The temperature sensor is supplied with a 40 ft.
Cable.
CONTROL MODULE
The function of the Control Module is to activate its control relays when ever user selected
temperature vales are reached and sustained for user determined periods of time. The Control
Module is microprocessor based and is controlled via push buttons and a two-row-liquid-
crystal-display. There are Option Switches on the printed circuit board for selection of
temperature units (°F or °C) , for enabling the audible alarm, and a potentiometer for
controlling the LCD contrast.
User Interface
There are two modes of operation for the model WMS-T-AL Temperature Alarm. RUNNING
and PAUSED. The RUNNING mode is the normal operating mode when the unit is initially
powered up. The PAUSED mode is any state other than the normal OPERATING mode.
Pressing any button during the RUNNING mode will place the unit in the PAUSED mode.
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