Bulletin H-WHT
Series WHT Weather-Proof Humidity/Temperature Transmitter
Specifications - Installation and Operating Instructions
2X 5/16 [7.94]
3-31/64
[88.5]
3
4-9/16
[115.89]
2-3/4
[69.85]
[76.2]
1-27/64
[36.12]
[101.6]
1-31/64
[37.70]
4
The Compact Series WHT Humidity/Temperature
Transmitter is designed to withstand the elements. A removable
sintered filter protects the polymer capacitance sensor from solid
objects that may come in contact with the transmitter. The
transmitter is available with 4 to 20 mA, or 0 to 10 VDC or 0-5V
output signals for both temperature and humidity or a passive
thermistor for temperature. This transmitter is ideal for measuring
outside air temperature and humidity levels for air handling
economizer applications.
INSTALLATION
Warning: Disconnect power supply before installation to prevent
electrical shock and equipment damage.
Make sure all connections are in accordance with the job wiring
diagram and in accordance with national and local electrical
codes. Use copper conductors only.
Caution: Use electrostatic discharge precautions (e.g., use of
wrist straps) during installation and wiring to prevent equipment
damage.
Avoid locations where severe shock or vibration, excessive
moisture or corrosive fumes are present. NEMA Type 3S (IP54)
housings are intended for outdoor use primarily to provide a
degree of protection against wind-blown dust, and rain.
Do not exceed ratings of this device, permanent damage not
covered by warranty may result. The 4-20 mA models are not
designed for AC voltage operation.
SPECIFICATIONS
Relative Humidity Range: 0 to 100% RH.
T
emperature Range: -40 to 140°F (-40 to 60°C).
Accuracy, RH: ±3% 20-80% RH, ±4% @ 10-20%, 80-90%.
Accuracy, Temp, Models with 4-20mA Temp. Output:
±0.9°F@ 72°F (±0.3°C @ 25°C).
Accuracy, Models with Passive Thermistor Temp Sensor:
±0.4°F @ 77°F (±0.22°C @ 25°C ).
Hysteresis, RH: ±1%.
Repeatability, RH: ±0.1% typical.
Temperature Limits: -40 to 140°F (-40 to 60°C).
Storage Temperature: -40 to 176°F (-40 to 80°C).
Compensated Temperature Range, RH: -4 to 140°F (-20 to
60°C).
4-20 mA Loop Powered Models:
Power Requirements: 10-35 VDC.
Output Signal: 4-20 mA.
0-10V Output Models:
Power requirements: 15-35 VDC or 15 –29 VAC.
Output Signal: 0-10V @ 5 mA max.
0-5V Output Models:
Power requirements: 10-35 VDC or 10–29 VAC.
Output Signal: 0-5V @ 5 mA max.
Response Time: 15 seconds.
Electrical Connections: Removable screw terminal block.
Drift: <1% RH/year.
RH Sensor: Capacitance polymer.
Temperature Sensor: 4-20mA Output, Solid State Band Gap.
Passive Output: 10K @ 25°C Thermistor (Dwyer curve A).
Housing Material: ABS.
Enclosure Rating: Designed to meet NEMA 3S (IP54).
Weight: 0.3oz (8.5g).
Agency Approvals: CE.
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MOUNTING
TEMP. RECEIVER
+–
+–
RH RECEIVER
POWER
SUPPLY
+
–
1 2 3 4
1 2 3 4
TEMP. SENSOR
+–
RH RECEIVER
POWER
SUPPLY
+
–
POWER
SUPPLY
+
–
TEMP. RECEIVER
+–
+–
RH RECEIVER
1 2 3 4 5
WIRING
1 2 3 4 5
TEMP. SENSOR
+–
RH RECEIVER
POWER
SUPPLY
+
–
The transmitter should be mounted with the sensor pointing
downward to prevent water collection in the housing. The integral
mounting tab has two sets of mounting holes. The larger holes are
for the suspension mounting and the smaller holes are for surface
mounting the transmitter to a wall. Please see Figure 1 and 2 for
more information on both mounting methods.
Figure 1 Suspension Mounting Figure 2 Surface Mounting
WIRING
Use maximum 18 AWG wire for wiring terminal. Refer to Figures 36 for wiring information.
Models with 4-20mA RH Output, with or without 4-20mA
Temperature Output
4-20 mA output units may be powered with a 10-35 VDC supply.
The following describes the proper wiring of these transmitters
with mA output.
Models with 4-20mA RH and 4-20mA Temperature outputs are
designed as a 4-20mA device with two channels. The channels
are common on the positive side of the current loop.
Sensor excitation is derived from the relative humidity channel, so
power must always be applied to that channel. If the temperature
channel is not equipped or used, it can be left disconnected. Wire
as shown in Figure 3.
Figure 3
Models with 4-20mA RH Output and a Passive Thermistor
Temperature Sensor
The 4-20mA RH output is identical to the above model with a 420mA temperature output. The required power supply and wiring
of the RH output is the same. The passive thermistor temperature
sensor wires to terminals 3 and 4. Wire as shown in Figure 4.
Figure 5
Models with 0-5 or 0-10V RH Output and a Passive
Thermistor Temperature Sensor
The 0-5V or 0-10V RH output is identical to the above model with
a 0-5V or 0-10V temperature output. The required power supply
and wiring of the RH output is the same. The passive thermistor
temperature sensor wires to terminals 4 and 5. Wire as shown in
Figure 6.
Figure 6
CHECKOUT
4-20 mA Models:
Verify appropriate supply voltage. The transmitter requires a
minimum of 10 and a maximum of 35 VDC at its connection for
proper operation. Choose a power supply with a voltage and
current rating which meets this requirement under all operating
conditions. If the power supply is unregulated, make sure voltage
remains within these limits under all power line conditions. Ripple
on the supply should not exceed 100 mV.
Loop Resistance – The maximum allowable loop resistance
depends on the power supply voltage. Maximum loop voltage
drop must not reduce the transmitter voltage below the 10 VDC
minimum. Maximum loop resistance can be calculated with the
following equation. Vpsis the power supply voltage.
V
-10.0
R
max
ps
=
20 mA
Some receivers, particularly loop powered indicators, may
maintain a fixed loop voltage to power the device. This voltage
drop must also be subtracted from the power supply voltage when
calculating the voltage margin for the transmitter. The following
equation takes this into account. V
R
max
Vps-10.0-V
=
rec
20 mA
is the receiver fixed voltage.
rec
0-5, 0-10 V Output Models:
Verify appropriate supply voltage. The 0-10V output models
require a DC supply of 15 to 35 V or an AC supply of 15-29 V for
proper operation maximum. The 0-5 V output models require a DC
supply of 10-35 V or an AC supply of 10-29 VAC. Both outputs
may be loaded simultaneously with 5 mA.
Figure 4
Models with 0-5V or 0-10V RH Output, with or without 0-5V
or 0-10V Temperature Output
The 0-10V output models may be powered with 15-35 VDC or 1529 VAC. The 0-5V models may be powered with 10-35 VDC or
10-29 VAC. Note the polarity when using DC power. The channels
are common on the negative side. For RH and Temperature
outputs, either or both may be used. The maximum load is 5mA
(1K for 0-5V, 2K for 0-10V). Wire as shown in Figure 5.
MAINTENANCE
Upon final installation of the Series WHT Temperature/Humidity
T ransmitter and the companion r eceiver, no routine maintenance is
required. A periodic check of the system calibration is
recommended. The Series WHT is not field serviceable and should
be returned if repair is needed (field repair should not be attempted
and may void warranty). Be sure to include a brief description of
the problem plus any relevant application notes. Contact customer
service to receive a return goods authorization number before
shipping.
©Copyright 2008 Dwyer Instruments, Inc. Printed in U.S.A. 10/08 FR# 03-443597-00
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