25
Once a year the pressure transducers should be checked
against a pressure gage. Attach a set of accurate refrigeration
gages to the transducer being checked and compare the two
readings. If there is a difference the transducer can be calibrat-
ed as described below (the Oil Pump Delta P reading should be
zero when the compressor is off). Calibration requires Service
level access to the HMI.
NOTE: It is usually not necessary to calibrate at initial start-up
unless chiller is at high altitude.
1. Go to Main Menu
Maintenance Menu
Pressure
Sensor Calib. See Fig. 34 and 35.
2. Each transducer is supplied with 5 vdc from the IOB.
Calibration is done by selecting the appropriate Pressure
Sensor option on the Pressure Sensor Calib screen. The
screen for the selected option is displayed. Figure 36
shows the Evap Pressure Sensor screen (PRSCAL01 as
an example.
3. Set Calibration Enable to Enable.
Calibration for this sensor is complete and the new slope
and intercept will be used for the calibrated transducer in
the pressure or temperature tables.
4. With the transducer at atmospheric pressure (zero gage
pressure), ensure that “Calib Press1 (0 PSI)” = 0 PSIG.
5. Pressurize the transducer to a known pressure between
100 and 250 psig, and enter that pressure as read from
calibrated gage in the “Calib Press2 (100-250PSI)”
field and press “OK.”
6. Screen will show “Calibration Completed = Yes” upon
successful calibration. To exit, use the arrow key or click
the Home button.
TEMPERATURE SENSOR CALIBRATION — The four
water temperature sensors can be separately calibrated to have
their temperature readings offset by a specified amount. Follow
these steps for each sensor:
1. Go to Main Menu
Maintenance Menu
Temp Sen-
sor Calib. See Fig. 37.
a19-2233
PRESSURE - Pressures
Fig. 32 — Pressures Screen, Page 1
a19-2234
PRESSURE - Pressures
Fig. 33 — Pressures Screen, Page 2
a19-2235
Pressure Sensor Calib
Fig. 34 — Pressure Sensor Calib Screen, Page 1
a19-2236
Pressure Sensor Calib
Fig. 35 — Pressure Sensor Calib Screen, Page 2
a19-2237
PRSCAL01 - Evap Pressure Sensor
Fig. 36 — Evap Pressure Sensor Screen
