Fridgewatch 2100 Controller Mk4
Publication 3-58
Section 3
Page 124 of 152
Issue 1.1 : 01/08
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.
(e)
Remove the temperature transducer from the ice water, insert the
tip of the probe into the container of warm water. Stir the water for
2 minutes while noting the temperature with the thermometer.
(f)
Check the thermometer reading against the reading on the
DISPLAY; the readings should be within
±
0.02 °C. If outside this
accuracy, adjust the Gain potentiometer using the method
described in step (d) for the Zero potentiometer.
(g)
Repeat step (c) to confirm that calibrating the Gain potentiometer
has not caused the zero point to drift.
(h)
If, after fully adjusting the potentiometers, readings to the required
accuracy cannot be achieved then the transducer or
interconnecting wiring is probably defective.
(i)
Record calibration details on a record sheet.
12.3.
Calibration of Motor Current
(a)
Set Fridgewatch 2100 to commissioning mode (S36 = 1).
(b)
Stop the compressor(s) by pressing the STOP COMPRESSORS
(ALL MODES) button.
(c)
Set Fridgewatch 2100 to display motor current (P5) for compressor
1.
Adjust the motor current Zero ZD potentiometer on the 3MIO1 card
for compressor 1 until 0 amps is displayed.
(d)
Set Fridgewatch 2100 to display motor current (P5) for compressor
2.
Adjust the motor current Zero ZB potentiometer on the 3MIO2 card
for compressor 2 until 0 amps is displayed.
(e)
Set Fridgewatch 2100 to display motor current (P5) for compressor
3.
Adjust the motor current Zero ZB potentiometer on the 3MIO2 card
for compressor 3 until 0 amps is displayed.
(f)
Start compressor 1 and allow operating conditions to stabilise.
(g)
Set Fridgewatch 2100 to display motor current (P5) for compressor
1.
(h)
Measure compressor 1 motor current using an accurate, clamp
type ammeter. Adjust the motor current gain potentiometer for
compressor 1 (Gain GD potentiometer on the 3MIO1 card) until
Fridgewatch 2100 displays the same current as measured by the
ammeter.
(i)
Repeat steps (f) to (h) for compressor 2 using the appropriate gain
potentiometer (Gain GB potentiometer on the compressor 2 3MIO2
card).