Model HU-224/225
Technical Information
TI.224/225-08
HUMIDITY SENSOR
Page 2 of 4
TYPICAL APPLICATIONS (wiring diagrams)
HU-224/225 humidity transducers are 4–20 mA output units powered with a 12–40 VDC supply.
The following describes the proper wiring of these humidity transducers with mA output:
1. Remove the terminal block by carefully pulling it off the circuit board.
2. Locate the [+] and [-] terminal markings on the board.
3. Attach the supply voltage to the [+] lead.
4. Connect the 4–20 mA output ([-] terminal) to the controller’s input terminal.
5. Ensure that the power supply common is attached to the common bus of the controller.
6. Re-insert the terminal block to the circuit board and apply power to the unit.
7. Check for the appropriate output signal using a DVM set on DC milliamps connected in series with the [-] terminal.
Input Signal
+
Common
+
+
Shield/Ground
Controller / Meter / Recorder
mA Output Transducer Only
12–40 VDC Power Supply
Input Signal
+
Common
+
Shield/Ground
Controller / Meter / Recorder
mA Output Transducer Only
Figures 1 & 2
illustrate typical wiring diagrams for the HU-224/225, 4–20 mA, two-wire humidity transducers.
Figure 1 –
Wiring for mA Output Humidity Transducers with External DC Power
Supply.
Figure 2 –
Wiring for mA Output Humidity Transducers where Controller or
Meter has Internal DC Power Supply.
If you are using grounded AC, the hot wire must be on the [+] terminal. Also, if you are using a controller without built-in isolation, use an isolation transformer to
supply the HU-224/225 transducer.
This product contains a half-wave rectifier power supply and must not be powered off transformers used to power other devices utilizing non-isolated full-wave
rectifier power supplies.
When multiple HU-224/225 units are powered from the same transformer, damage will result unless all 24G power leads are connected to the same power lead on
all devices. It is mandatory that correct phasing be maintained when powering more than one device from a single transformer.
RoHS
HU-224
Duct Mount
HU-225
Wall Mount
Wiring HU-224/225 Units with mA Output
mA Output
CAUTION!
S Z
SPAN
ZERO
- +
Z S
+ -
SPAN
ZERO
