EWS-RH
Relative Humidity/Temperature Transmitter
7
Temperature Calibration Procedure
Recommended equipment:
Series 860 Thermistor Meter OMEGA
®
Model No. 865F or 865C
Series 400 Thermistor Probe, OMEGA
®
Model No.: ON-406-PP
Handheld Digital Multimeter, OMEGA
®
Model No.: HHM29
1. Remove enclosure cover.
2. Connect transmitter as shown in figure below.
3. Apply power to transmitter and allow to warm up for 10 min.
4. Place unit on workbench with temperature reference probe next to unit.
5. Allow output from transmitter and reference probe to stabilize.
6. Observe the reading on the handheld thermometer coming from the
reference probe.
7. Without touching the unit with your hand, adjust potentiometer “P4” for
a current output of the transmitter that matches the temperature
measured by the reference probe. Note: if you hold the unit with your
hand, the unit will sense heat from your hand and cause a bad
calibration.
Use this formula:
(
Ambient - 5 x 16
)
+4
135
Example:
If your reference probe measures 70°F (21.11°C) you need to adjust the
transmitter’s current output to be 11.70 mA.
8. Calibration complete.
Figure 5: Temperature Calibration Procedure
MULTIMETER
POWER SUPPLY
1
6
+
+
–
–
5
4
3
2
1 1 . 7 0 m A
P 4
