User’s Guide
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WMS-T-AL
Dual Set Point Temperature Alarm
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.
1
MENU STRUCTURE
The user interface contains the following menu items:
• Temperature Alarms
• Alarm Delays
• Maximum/Minimum Temperature
The MENU Button
The MENU button will take the unit out of the RUNNING mode and allow the user to change
the operating parameters and view maximum values.
Once the MENU button has been pressed the user may use the UP and DOWN buttons to scroll
through the menu.
Subsequent presses of the MENU button will bounce the cursor between editable fields of any
menu item, where applicable. When in an editable field, the cursor will become a blinking
block.
The GO Button
The GO Button always returns the unit to the RUNNING mode, regardless of where the user
may be in the menu structure.
The UP and DOWN Buttons
The UP and DOWN buttons control either of two things:
1. Scrolling through menu items when the user is not in an editable field.
2. Scrolling through user selectable values when the user is in an editable field.
The CLEAR Button
Pressing the CLEAR button performs the following actions:
1. If the user is in an editable field, the field will be set to 0.
2. It the user is viewing the maximum/minimum temperature value, the recorded
value will be cleared.
3. If the unit is alarming, all delay counters will be cleared.
ALARM Features
The WMS-T-AL Temperature Alarm provides the following alarm features:
• Two independent temperature alarms
• Programmable On and OFF delays
• Pausing of alarm when any key is pressed
2
• When audible, Alarm 1 will produce a beep at 400 ms intervals while Alarm 2 will
beep at 200 ms intervals.
• When the alarms are in the audible mode and both alarms are active, Alarm 2 will
have precedence.
• The alarm can be put into the silent mode by moving Switch 4 to the off position on
the switch block at the bottom of the circuit board. It is necessary to re-boot the
WMS-T-AL after moving the switch in order to in able the change.
Units of Measure
It is possible to display temperature values in either °F or °C units. Selection of the unit system
to be used is done with Switch 3 on the switch block at the bottom of the circuit board. The Off
position is for °F and the On position is for °C. It is necessary to re-boot the WMS-T-AL after
moving the switch in order to in able the change.
Temperature Sensor Placement
The validity of temperature signals can be compromised by the choice of the location of the
anemometer with respect to the surrounding terrain. Placement of the temperature sensor
should follow standards established by agencies such as the World Meteorological Organization
(WMO) and the National Oceanic and Atmospheric Administration’s (NOAA) National
Weather Service (NWS).
Temperature Inputs
The temperature inputs are P17, TMP1 and P18, TMP2.
Power Supply
Use a 12V AC or DC power supply on the ACin/DCin and ACin/DCgnd terminals.
Earth Ground
Attach a wire of at least 18 AWG or larger to the EARTH terminal. The other end of this wire
must be attached to a metal water pipe or a copper-ground-rod. This is the ground path for all
of the lightning and electrostatic protection devices incorporated on the WMS-T-AL circuit
board. It is very important that this earth ground connection is made! Your WARRANTY may
be voided if the earth ground connection is not made.
3
QUICK START
Before permanently installing the WMS-T-AL it is advisable to “bench test” it to gain familiarity
with its operation. The test is conducted in the following manner.
Attach the temperature sensor leads to the terminals on the WMS-T-AL circuit board labeled
TMP1 and TMP2.
Attach 12V dc or ac to the terminals on the WMS-T-AL circuit board marked AC in/DC in and
AC in/DC gnd.
When the WMS-T-AL circuit board is energized the LCD is activated and it will display the
temperature on the first line and the alarm set point values on the second line.
There are five con
trol buttons next to the LCD. These are used to set the alarm thresholds for the
two alarms, to set the delay times between the time that the temperature crosses the alarm
threshold and when the alarm state changes conditions, and to clear the maximum and
minimum temperature value in the temperature log. The default condition for the temperature
alarms is 75°F.
Both the on-delay and the off-delay default values are 15 seconds.
To change the temperature alarm threshold value press the Menu button. The top line of the
display will change from “Temp XX.X (°F)” to “Temp Alarms (°F)”. Press the Menu button
again and the cursor moves over the Alarm 1 temperature value. Press the Up or Dn button to
increment or decrement the alarm threshold value for Alarm 1. Press the Go button to return to
the RUNNING mode. Repeat the process for Alarm 2.
To Change the Alarm On and Alarm Off delays, with the unit in the RUNNING mode press the
Menu then press the Up button until the “Alarm Delays (s)” menu appears. Press the Menu
button and the cursor will move to the “ON: XX” field. Then Press the Up or Dn button to
increment or decrement the On delay value to the desired value. Press the Menu button again
to advance the cursor to the “OFF: XX” field and adjust the value with the Up or Dn button.
Press the Go button to return to the RUNNING mode.
To view the Minimum and Maximum Temperature registers from the RUNNING mode press
the Menu button, then press the Up button until the “Temps (°F)” screen is displayed and the
second line will show the minimum and maximum temperatures obtained since the last reset.
To reset the maximum wind speed value to zero press the Clr button. Press the Go button to
return to the RUNNING mode.
This concludes the series of quick start tests.
4
SPECIFICATIONS
Sensor Unit
Sensor
Thermistor, 10K ohms
Accuracy: 1°F @ 77°F
Alarm Delay Range ON or Off
0 - 99 seconds
Controls
Four, push buttons select:
1. Run or Pause mode
2. Menu Select
3. Increment
4. Decrement
Option slide switch: (Switches are read only during power-up.)
Switch 1: ON = TEMPERATURE
Switch 2: N.A
Switch 3:
ON = °C; OFF = °F
Switch 4: ON = Audible alarms, OFF = Silent alarms
5
NOTES:
WARRANTY/DISCLAIMER
OMEGA ENGINEERING, INC. warrants this unit to be free of defects in materials and workmanship for a
period of 13 months from date of purchase. OMEGA’s WARRANTY adds an additional one (1) month
grace period to the normal one (1) year product warranty to cover handling and shipping time. This
ensures that OMEGA’s customers receive maximum coverage on each product.
If the unit malfunctions, it must be returned to the factory for evaluation. OMEGA’s Customer Service
Department will issue an Authorized Return (AR) number immediately upon phone or written request.
Upon examination by OMEGA, if the unit is found to be defective, it will be repaired or replaced at no
charge. OMEGA’s WARRANTY does not apply to defects resulting from any action of the purchaser,
including but not limited to mishandling, improper interfacing, operation outside of design limits,
improper repair, or unauthorized modification. This WARRANTY is VOID if the unit shows evidence of
having been tampered with or shows evidence of having been damaged as a result of excessive corrosion;
or current, heat, moisture or vibration; improper specification; misapplication; misuse or other operating
conditions outside of OMEGA’s control. Components in which wear is not warranted, include but are not
limited to contact points, fuses, and triacs.
OMEGA is pleased to offer suggestions on the use of its various products. However,
OMEGA neither assumes responsibility for any omissions or errors nor assumes liability for any
damages that result from the use of its products in accordance with information provided by
OMEGA, either verbal or written. OMEGA warrants only that the parts manufactured by the
company will be as specified and free of defects. OMEGA MAKES NO OTHER WARRANTIES OR
REPRESENTATIONS OF ANY KIND WHATSOEVER, EXPRESSED OR IMPLIED, EXCEPT THAT OF
TITLE, AND ALL IMPLIED WARRANTIES INCLUDING ANY WARRANTY OF MERCHANTABILITY
AND FITNESS FOR A PARTICULAR PURPOSE ARE HEREBY DISCLAIMED. LIMITATION OF
LIABILITY: The remedies of purchaser set forth herein are exclusive, and the total liability of
OMEGA with respect to this order, whether based on contract, warranty, negligence,
indemnification, strict liability or otherwise, shall not exceed the purchase price of the
component upon which liability is based. In no event shall OMEGA be liable for
consequential, incidental or special damages.
CONDITIONS: Equipment sold by OMEGA is not intended to be used, nor shall it be used: (1) as a “Basic
Component” under 10 CFR 21 (NRC), used in or with any nuclear installation or activity; or (2) in medical
applications or used on humans. Should any Product(s) be used in or with any nuclear installation or
activity, medical application, used on humans, or misused in any way, OMEGA assumes no responsibility
as set forth in our basic WARRANTY/DISCLAIMER language, and, additionally, purchaser will indemnify
OMEGA and hold OMEGA harmless from any liability or damage whatsoever arising out of the use of the
Product(s) in such a manner.
RETURN REQUESTS/INQUIRIES
Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department. BEFORE
RETURNING ANY PRODUCT(S) TO OMEGA, PURCHASER MUST OBTAIN AN AUTHORIZED RETURN
(AR) NUMBER FROM OMEGA’S CUSTOMER SERVICE DEPARTMENT (IN ORDER TO AVOID
PROCESSING DELAYS). The assigned AR number should then be marked on the outside of the return
package and on any correspondence.
The purchaser is responsible for shipping charges, freight, insurance and proper packaging to prevent
breakage in transit.
FOR WARRANTY RETURNS, please have the
following information available BEFORE
contacting OMEGA:
FOR NON-WARRANTY REPAIRS, consult OMEGA
for current repair charges. Have the following
information available BEFORE contacting OMEGA:
1. Purchase Order number under which the product
was PURCHASED,
1. Purchase Order number to cover the COST
of the repair,
2. Model and serial number of the product under
warranty, and
3. Repair instructions and/or specific problems
relative to the product.
2. Model and serial number of the product, and
3. Repair instructions and/or specific problems
relative to the product.
OMEGA’s policy is to make running changes, not model changes, whenever an improvement is possible. This affords
our customers the latest in technology and engineering.
OMEGA is a registered trademark of OMEGA ENGINEERING, INC.
© Copyright 2007 OMEGA ENGINEERING, INC. All rights reserved. This document may not be copied, photocopied,
reproduced, translated, or reduced to any electronic medium or machine-readable form, in whole or in part, without the
prior written consent of OMEGA ENGINEERING, INC.
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