Advantage OACS Series, Instruction Manual

Page: 79 / 86

OACS Central Chillers : with MG Series Control Instrument
Page: 79
ADVANTAGE ENGINEERING, INC.
525 East Stop 18 Road Greenwood, Indiana 46142
317-887-0729 Fax: 317-881-1277
Service Department Fax: 317-885-8683
Email: service@AdvantageEngineering.com
8.6 PROBE CALIBRATION : MG Instrument
A. Equipment Needed:
1. Potentiometer adjustment tool / flat-blade screw driver (tip width of 0.050” or less
works best
2. Temperature reference (ice water bath)
3. 1/2” plug
4. Digital thermometer
5. Screwdriver (chassis disassembly)
B. Setup:
1. Disengage process operations according to the procedure outlined in the unit
manual. The operator must be certain all system pressure is relieved and unit
pressure gauges read “0”.
2. Following all lock-out-tag-out procedures disengage main power supply.
3. Remove the “to process” temperature probe and insert a ½” plug in its place.
4. Prepare an ice bath (a cup of water with lots of ice). You should place a digital
thermometer in the ice bath to read the temperature of the bath. Place the probe
in the ice bath.
C. Procedure:
1. Restart the instrument according to the procedures outlined in the unit manual.
2. Reduce the unit’s setpoint to its lowest setting.
3. The “to process” temperature on the display should equal the temperature of the
ice bath as indicated by the digital thermometer. If not, change the calibration.
4. The calibration potentiometer is located on the top of the CPU board. To access
it, open the electrical cabinet panel door. Caution must be employed when the
electrical panel door is open since power is applied to unit.
5. Locate the “to process” calibration potentiometer using Figure 1 as a guide. Use
the small screwdriver to turn the potentiometer.
6. Adjust the potentiometer until the “to process” temperature on the display equals
the temperature of the ice bath.
7. When the two temperatures are equal, the calibration procedure is complete.
NOTE: the optional “from process” probe has its own calibration potentiometer.