Fridgewatch 2100 Controller Mk4
Publication 3-58
Section 3
Page 122 of 152
Issue 1.1 : 01/08
12. Maintenance
Under normal operating conditions with the Fridgewatch 2100 Controller
operating correctly, minimum servicing is required or recommended. The
following general checks are recommended once a year.
•
Check measured point values against pressure gauges,
thermometers and current meter readings.
•
Check for damage to external wiring.
•
Check screw terminals, fuseholders etc., for loose
connections.
A full transducer calibration check is recommended every 5 years. The
lithium battery used to back up Fridgewatch 2100 settings should be
checked after 5 years, then every year until the battery needs replacing;
refer to 12.7. Checking and Replacement of Lithium Back-up Battery.
12.1.
Calibration of Pressure Transducers
The following equipment is required:
•
Accurate pressure gauge with a calibrated range of
approximately 0 bar to 10 bar and 0 bar to 20 bar
(depending on the range of the transducer).
•
Hand pressure pump or other controllable pressure source.
•
Necessary pipes and couplings.
•
Potentiometer trimmer or instrument screwdriver.
Refer to the 3MIO1 and3MIO2 input/output card illustrations in Fig 23 and
Fig 25.
Calibrate the pressure transducer as follows:
(a)
Close the stop valve to isolate the pressure transducer; refer to Fig
10.
(b)
Disconnect the pressure pipe from the transducer. Leave the input
port of the transducer open to atmospheric pressure.
(c)
Set the Fridgewatch 2100 Controller to display the measured point
under test. The DISPLAY on the front panel should read 0.00 bar
±
0.05 bar.
(d)
If the DISPLAY reading is outside these parameters, locate the
input/output card for the measured point 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.
Slowly adjust the Zero potentiometer, at the same time watch for
the corresponding LEDs to flash indicating that the point has been
scanned by the Fridgewatch 2100 Controller microprocessor for
display on the front panel.
While checking the DISPLAY, continue to adjust the Zero
potentiometer until the reading is within the required accuracy.
The potentiometer has ten turns either way for adjustment.
