Omega | OM-THA2-U | Owner Manual | Omega OM-THA2-U Owner Manual

Omega OM-THA2-U Owner Manual
User’s Guide
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Alarm With Logging Capacity
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Omega Engineering, Inc.
Toll-Free: 1-800-826-6342 (USA & Canada only)
Customer Service: 1-800-622-2378 (USA & Canada only)
Engineering Service: 1-800-872-9436 (USA & Canada only)
Tel: (203) 359-1660
Fax: (203) 359-7700
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The information contained in this document is believed to be correct, but OMEGA accepts no liability for any errors it contains, and reserves
the right to alter specifications without notice.
The OM-THA2-U is a multi-function product that monitors Temperature, Humidity
and Dew Point, provides alarms for out of range conditions, and continuously logs
data. It consists of a base unit with an easy to read display, and a remote sensor
probe that can support cable lengths of up to 300 feet. The unit comes with a 15
feet sensor cable.
The alarm function monitors the temperature, humidity, and dew point once every
second. If any of the readings reach an alarm threshold, the unit generates an
alarm by turning on a beeper and a dry contact relay. The relay can be connected
to a telephone dialer, light, or a bell. The delayed alarm feature can reduce false
alarms, by ignoring short duration alarm conditions. The unit will also generate and
alarm on probe failure.
The logger function records the temperature humidity and dew point into internal
non-volatile memory at a user specified interval. The recording is performed
continuously after the unit is turned on. No computer setup is necessary to start
logging, and all logging settings can be viewed or changed through the front panel
functions. When the internal memory becomes full, the recording rolls over,
overwriting the oldest recorded data. For a 2 minute recording rate, this provides
the user with an 11 day history of the temperature, humidity, and dew point data.
This data can then be reviewed with PC software provided with the unit.
All the operating settings of the OM-THA2-U can be changed from the front panel,
without the need for a computer. The two line display provides an easy to read
means of viewing, or changing settings according to the user’s requirements. The
unit will simultaneously support review of logged data on a computer, while
continuously recording new data.
Front Panel Operation
The Display
During normal operation the display shows the temperature, humidity and dew
point on the bottom line. When either measurement is within the alarm threshold,
the value flashes. To adjust the display contrast, turn the contrast knob clockwise
(right) for the increased contrast, and counter-clockwise (left) to reduce the
contrast. The display periodically shows additional status information such as
date and time, battery backup operation, battery low condition (during battery
backup operation), and sensor failure.
Viewing and Modifying Current Alarm Thresholds
To view the current alarm or delay settings, press and hold the corresponding
button. For instance to view the temperature high alarm, press and hold the TEMP
HI button.
To modify an alarm threshold or alarm delay, press and hold the corresponding
button. While continuing to press the button, press the UP button to increase the
value, or DOWN button to decrease the value. Note, the UP and DOWN buttons
are only active if the alarm modification function is unlocked in the setup menu.
Silencing an Active Alarm
If an alarm is active, the SILENCE button will silence the beeper and deactivate
the relay. If the SILENCE button is pressed while there is no alarm, it has no
effect on the beeper operation. The Silence alarm function is only active during the
current alarm occurrence. Once the alarm condition is over and the unit returns to
the normal (non alarm) operation, the silence alarm function is automatically
Power and Relay Connections.
The OM-THA2-U has a 5 contact, screw type terminal block for power and relay
connections. The relay is located behind the gray door located in the lower left of
the front panel. The first two contacts are for power, and the remaining three
contacts for the relay. The relay supplied is capable of switching 5A at 250 VAC
max. Terminal 1 is on the left and terminal 5 is on the right.
1 and 2
12 to 24 volts AC or DC power input. These contacts do not
have a polarity.
Relay Contact, Normally Closed (N.C.)
Relay Contact, Common.
Relay Contact, Normally Open (N.O.)
An alarm is active when two conditions are met:
1. A measurement has reached one of the high or low alarms limits. The
measurement that has reached its limit will then flash on the display.
2. When the first condition has been reached, and the delay time has ended, the
beeper will turn on, and the relay will close.
Alarm Delay
The DELAY button provides the user with the ability to make sure that an alarm
condition has been present for a minimum period of time. The time period can
range from no delay, to two hours. The use of delay can reduce or eliminate the
occurrence of false alarms. The user needs to carefully consider their application
in order to achieve the best results. There are nine delay settings:
Delay Settings
• No delay
• 10 seconds
• 1 Minute
• 20 Minutes
• 30 minutes
• 1 Hour
• 90 Minutes
• 2 Hours
Dew Point (Condensation) Alarm
The Dew Point Alarm alerts the user when condensation is imminent.
Condensation occurs when the ambient temperature drops to the dew point
temperature. The dew point alarm becomes active when the ambient temperature
has dropped to within a user specified threshold of the Dew Point temperature. To
understand this, reference the graph below.
The Dew Point Alarm was set to 6°F. As the dew point temperature approaches
the ambient temperature, the danger of condensation increases. When the dew
point is within 6°F from the ambient temperature (dew point is 64°F while the
ambient temperature is 70°F), the dew point alarm is activated, alerting the user
that condensation is very likely. Condensation finally occurs when the dew point
temperature and the ambient temperature are the same — 70°F. This also means
that the relative humidity is now 100%RH.
Disabling Alarms
You can disable any high or low alarm by setting the threshold to its maximum or
minimum value:
• To disable the low temperature alarm, set the TEMP LO threshold to 40°F (-40°C).
• To disable the low humidity alarm set the HUM LO threshold to 0 %RH.
• To disable the high temperature alarm, set the TEMP HI threshold to 140°F
• To disable the high humidity alarm, set the HUM HI threshold to 100 %RH.
• To disable the dew point (condensation) alarm, set the DEW threshold to 0°F
or 0°C.
An alarm will always occur when condensation occurs (100%RH, or the Dew Point
is equal to the ambient temperature).
Setup Menu
The setup menu allows the user to modify settings that do not need to be changed
very often. To enter the setup menu, press and hold the UP and DOWN buttons at
the same time, for about three seconds.
Once the menu comes up, use the UP or DOWN buttons to move between menu
entries, and use the TEMP HI button to select an item to view, or change. After
the entry has been selected, the TEMP HI
button is used to”enter” the data. To exit setup, the user can scroll to the Exit
entry and press TEMP HI, or press the DELAY button for a quick exit. There are
nine entries in the setup menu:
Setup Menu
• Set Time
• Sampling Rates
• Alarm Buttons
• Time Format
• Exit
• Set Date
• Units
• Calibrate Probe
• Date Format
• Set Time - Sets the current time of day. Press UP or DOWN to change the
hours, and press TEMP HI to move to the minutes field. Pressing TEMP HI on
the minutes field sets the time and returns to the setup menu. TEMP LO button
can be used to move backwards from the minutes field to the hours field.
• Set Date - Sets the current date. Press UP or DOWN to change the values, and
press TEMP HI to move to the next field, and TEMP LO to move to the previous
field. Pressing TEMP HI on the year field sets the date and returns to the setup
• Sampling Rates - Sets the sampling rate for the data logger function of the
OM-THA2. On entry, the display shows the current sampling rate, and how much
data history this sampling rate provides. Press UP or DOWN to change the
sampling rate and TEMP HI when done. The twelve sampling rates are:
Sampling Rate
1 Second
2 Seconds
5 Seconds
10 Seconds
20 Seconds
30 Seconds
1 Minute
2 Minutes (default)
5 Minutes
10 Minutes
15 Minutes
30 Minutes
Data History Length
2 Hours, 15 Minutes
4 Hours, 30 Minutes
11.5 Hours, 30 Minutes
23 Hours
46 Hours
2.4 Days
5.7 Days
11 Days
28 Days
56 Days
85 Days
170 Days
• Units - Allows the user to set the display format to °F or °C for all temperature
and dew point measurements. Press UP or DOWN to choose the units.
Press TEMP HI when done
• Alarm Buttons - The alarm buttons can be used for both viewing and changing
alarm limits. To prevent accidental changes the alarm buttons can be “locked”,
so that alarms can only be viewed, but not changed. This prevents accidental
changing of alarm values during normal use. Use UP or DOWN to select
Unlocked or Locked. Press TEMP HI when done.
• Calibrate Probe - The user can adjust the temperature and humidity readings
to match external references. To start calibration, select the Calibrate Probe
option by pressing TEMP HI. The display will show Calib. Temp? No. Use UP
to change to YES, and then press TEMP HI. The display shows the
temperature and current offset. Now, the user can press UP and DOWN to
adjust the temperature in 0.1 degree steps. The temperature can be calibrated
+/- 4 °F or °C degrees. Press TEMP HI when done. Humidity is calibrated in
the same way. To Turn off the calibration for temperature of humidity, set the
offset to zero.
• Date Format - There are three formats available: MM/DD/YY, DD/MM/YY, or
DD.MM.YY. Use UP or DOWN to select the format, and then press TEMP HI
when done.
• Time Format - The user can select 12 hour or 24 hour clock format for the
display. Use UP or DOWN to select the format, and then press TEMP HI when
• Exit - Press TEMP HI to exit the setup menu.
Battery Operation
The OM-THA2-U will work from a wide variety of power sources. It can operate
from 12V to 24V AC or DC source. Battery backup will provide 35 hours of
continued operation with a 9V alkaline battery. This battery should be changed
after every power failure. During a power outage, the message Battery Backup!
will flash every several seconds.
During a power failure, the unit will continue normal operation except during an
alarm. When the alarm becomes active, the relay will close for only thirty seconds
to conserve battery power.
Standalone front panel operation, with user lockout for security. PC software is
provided with the unit for viewing data history.
Sensor Probe
Operating Temperature Range
Operating Humidity Range
Temperature Accuracy
Temperature Resolution
Humidity Accuracy
Humidity Resolution
Cable Length
-40F° to 140°F (-40°C to 60°C)
0 to 90 %RH, non condensing
+/- 2°F (+/- 1°C)
0.1 °F or 0.1 °C
+/-2 %RH
0.1 %RH
User calibration for Temperature and Humidity
3.8 inches length with a diameter of 1.1 inches
0.9 oz.
Comes with 15ft cable. Can be extended to
300 ft. maximum.
Base unit
Operating Temperature Range
Storage Temperature
Operating Humidity
Power Source
Battery backup
32°F to 130°F (0°C to 54°C)
0°F to 130°F (-18°C to 54°C)
0 %RH to 90 %RH, non condensing *
12V to 24 VAC/VDC, 0.78W alarm active
9V alkaline battery for 35 hours operation
during power outage
Clock battery
CR2032, 10 years typical
N.O and N.C. dry contact 5A 250V, resistive
5.5" x 4.5" x 1.6"
Weight (without battery backup) 8.6 oz.
Alarm Specifications
Temperature Alarm
Condensation alarm
Alarm Delay
Alarm Indication
Logging Specifications
Sample Rate
Data history storage
Memory capacity
High and Low Temperature and Humidity
User selectable, up to 2 hours
Audio, Visual and a relay for remote alarm
and phone dialer
1 second to 30 minutes.
2 hours to 170 days, depending on the
sample rate
8150 samples for Temperature, Humidity, and
Dew Point
* The sensor probe is not designed for continuous exposure to high
humidity or caustic and or corrosive chemicals such as, but not limited to
concrete or chlorine.
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
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.
Direct all warranty and repair requests/inquiries to the OMEGA Customer Service Department.
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
OMEGA for current repair charges. Have
following information available BEFORE contacting
the following information available BEFORE
contacting OMEGA:
1. Purchase Order number under which the product
1. Purchase Order number to cover the COST
of the repair,
2. Model and serial number of the product under
2. Model and serial number of the product, and
warranty, and
3. Repair instructions and/or specific problems
3. Repair instructions and/or specific problems
relative to the product.
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 2016 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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