Carrier 040-420 Installation And Service Manual

Temperature Reset Based on External Temperature - If de-sired, temperature reset can be based on an external tem-perature, such as space or outdoor-air temperature. This re-quires a thermistor (TlO, Part No. 30GB660002) located inthe space or outdoor air and wired to terminals as follows(also see Field Wiring section on page 71):4 in/4 out Module - 57-15 and J7-16.At the field configuration step, select external tempera-ture reset by entering q when CRTYP 0 appears. Thenenter set points as described previously in Example 5. SeeFig. 5.Temperature Reset Based on 4-20 mA Signal- If desired,temperature reset can be based on a 4-20 mA signal. Forproper connections, refer to Field Wiring section on page71 and Fig. 6.At the field configuration step, select 4-20 mA reset byentering q when CRTYP 0 appears. Then enter set pointsas described previously in Example 5. See Fig. 7,Demand Limit, 2-Stage Switch Control - This control hasbeen designed to accept demand limit signals from a build-ing load shedding control. The demand limit function pro-vides for 2 capacity steps. The keypad is used to set the 2demand limit set points, which range from 100 to 0% ofcapacity. Capacity steps are controlled by 2 field-suppliedrelay contacts connected to the designated chiller terminals.(See Field Wiring section on page 7 1 and Fig. 6.)10 -Y-8-?-2-I -O-Example 6 - Changing Reset TypeTo change type of reset, first log on as shown inTable 11. Also refer to Set Point Function section, page 39,for information on entering reset set points using resetfeature.KEYPAD DISPLAYENTRY RESPONSE COMMENTSFLD CFGC S P T Y P 0CRTYP 0C R T Y P 1CRTYP 2CRTYP 3F i e l d c o n f i g u r a t i o ns u b f u n c t i o n o fs e r v i c e f u n c t i o nS c r o l l p a s t s i n g l e c o o l i n gset pointNo reset has beens e l e c t e dReturn water temperaturereset is selected anda c t i v a t e dReset type is changed tospace or outdoor-airtemperature reset anda c t i v a t e dReset type is changed to4-20 mA signal reseta n d a c t i v a t e dCRTYP 0 Reset is deactivated181686RESET REFERENCE TEMPERATURE (OUTDOOR AIR 1OR SPACE TEMPFig. 5 - Cooling External Temperature Reset4 1