Carrier 040-420 8- 16 ?, Example 6 - Changing Reset Type, Cooling External Temperature Reset

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 in the 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. Then enter set points as described previously in Example 5. See Fig. 5.

Temperature Reset Based on 4-20 mA Signal- If desired,

temperature reset can be based on a 4-20 mA signal. For proper connections, refer to Field Wiring section on page 71 and Fig. 6.

At the field configuration step, select 4-20 mA reset by entering q when CRTYP 0 appears. Then enter set points as described previously in Example 5. See Fig. 7,

Demand Limit, 2-Stage Switch Control - This control has been 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 2 demand limit set points, which range from 100 to 0% of capacity. Capacity steps are controlled by 2 field-supplied relay contacts connected to the designated chiller terminals. (See Field Wiring section on page 7 1 and Fig. 6.)

Example 6 - Changing Reset Type

To change type of reset, first log on as shown in Table 11. Also refer to Set Point Function section, page 39, for information on entering reset set points using reset feature.

KEYPAD	DISPLAY		COMMENTS
ENTRY	RESPONSE
		Field	configuration
	FLD CFG	subfunction of
		service function
	CSPTYP 0	Scroll	past single cooling
		set point
	CRTYP 0	No reset has been
		selected
		Return water temperature
	CRTYP 1	reset is selected and
		activated
		Reset type is changed to
	CRTYP 2	space or outdoor-air
		temperature reset and
		activated
		Reset type is changed to
	CRTYP 3	4-20 mA signal reset
		and	activated
	CRTYP 0	Reset is deactivated

10 -

Y- 18

8- 16 ?-

8

6

2-

I -

O-

RESET REFERENCE TEMPERATURE (OUTDOOR AIR 1OR SPACE TEMP

Fig. 5 - Cooling External Temperature Reset

4 1