Fridgewatch 2100 Controller Mk4
Section 3
Publication 3-58
Issue 1.1 : 01/08
Page 123 of 152
(e)
Connect the pressure pump and gauge to the transducer input
port. Which gauge to connect depends on the range of the
transducer. Apply a known pressure to the transducer (10 bar or
20 bar, depending on the range of the pressure transducer fitted)
and again note the reading on the DISPLAY; the readings should
be within
±
0.05 bar.
If outside this accuracy, adjust the Gain potentiometer using the
method described in step (d) for the Zero potentiometer.
(f)
Repeat step (c) to confirm that calibrating the Gain potentiometer
has not caused the zero point to drift.
(g)
If, after fully adjusting the potentiometers, readings to the required
accuracy cannot be achieved then the transducer or
interconnecting wiring is probably defective.
(h)
Record calibration details on a record sheet.
12.2.
Calibration of Temperature Transducers
The following equipment is required:
•
Container filled with clean water and ice mixture. The ice
should occupy at least 50 % of the container volume and
must be continuously stirred to make sure of an even
temperature throughout the mixture. Avoid contaminating
the mixture with salts as this will alter the temperature at
which the ice melts.
•
Container filled with clean warm water at approximately
40
°
C (or 90
°
C for the discharge temperature sensor).
•
An accurate thermometer with a calibrated temperature
range of approximately -10
°
C to +100
°
C.
It is only necessary to measure the temperature of the container of
warm water as the container of melting ice and water will be at
0
°
C.
•
Potentiometer trimmer or instrument screwdriver.
Refer to the 3MIO1 or 3MIO2 input/output card illustrations in Fig 23 or
Fig 25.
Calibrate the temperature transducer as follows:
(a)
Remove the temperature transducer from its location.
(b)
Place the tip of the transducer probe (approximately the first 100
mm) into the container of ice water. Stir the ice continuously for
two minutes and check with the thermometer that the water
temperature is at 0°C.
(c)
Set the Fridgewatch 2100 Controller front panel to display the
measured point under test. The DISPLAY should read 0.00 °C
±
0.02 °C.
(d)
If the temperature reading is outside these parameters, locate the
input/output card measuring the output under test; refer to Fig 23
and Fig 25.
Locate the Gain G and Zero Z potentiometers and scan LEDs
associated with the measured point under test.
