Carrier HS070-160 manual Control Sequence

Table 3 - Thermistors

Table 4 - Capacity Control Steps

CONTROL SEQUENCE

The control power (115-l-60 for 60-Hz units; 230-l-50 for 50-Hz units) must be supplied directly from a separate source through a code-approved fused disconnect to the Ll and L2 terminals of unit power teminal block.

NOTE: There is no switch or circuit breaker; only fuses. If the control power feed is live, so is the circuit.

Crankcase heaters are wired into the control circuit. They are always operative as long as control circuit power is on even though unit may be off because of safety device action. Heaters are wired so they are on only when their respective compressors are cycled off.

A,f’tor a prnlonged shutdoun, the crankcause heaters should be on ,for 24 hours hqfbre starting the unit.

When power is supplied to control circuit, unit is ready for operation providing all safety devices are satisfied, interlocks are closed and instructions on warning labels have been followed.

If schedule function is used, refer to page 11 for details on control operation.

UNIT	:ONTR
3 0 H R
	S T E P S
3 0 H S

	SEQUENCE A
	c		c
		?r Cylinders
%	-	EiiqTm-	-
			%
C a p .		C o m p r	Cap. rot.

ENCE 3

er Cylinders zlzqxi7

C o m p r

Off Cycle - During unit off cycle when the RUN; STANDBY switch is in the STANDBY position, the crankcase heaters and the control system are energized. The electronic expansion valves are also energized.

0 7 0

0 8 0

0 9 0

1 0 0

1 1 0

120, 1 6 0

1 4 0

			42
1 4 . 3		2	-
4 2	. 9	6	-
5 7	. 2	a
7 1	. 2	1 0	4
8 5	. 7
100.0		E	4
			-
2 5	. 0	4	-
5 0	. 0	a	-
6 2	. 5	1 0
7 5	. 0	1 2
8 7	. 5	1 4	4
100.0		1 6	4
			-
2 2	. 2	4	-
4 4	. 4	a
5 5	. 5	1 0	-
6 6	. 7	1 2
8 8	. 8	1 6	6
1 0 0 . 0		1 8	6
			-
2 0	. 0	4	-
4 0	. 0	8
5 0	. 0	1:
6 0	. 0
7 0	. 0		4
8 0	. 0	::	4
9 0	. 0	::	t
100.0
18	.2	4	-
3 6	. 3	a
4 5	. 4	10
5 4	. 5	:;
72	.7
8 1	. 8	hi
9 0	. 9
100.0		2 2
16	.6 4
3 3	. 3	a
4 1	. 6	1 0
5 0	. 0	1 2
6 6	. 7	1 6
7 5	. 0	1%
9 1	. 6	2 2
100.0		2 4
19	.0	4
3 8	. 0	a
4 7	. 6	1 0
5 7	. 0	1 2
6 9	. 0	1 6	6
7 8	. 6
9 0	. 4	:;	:
100.0		2 4	6

82
-	2&.6
-			4
-	4 2	. 9
	5 7	. 2	:
-	7 1	. 2	1 0
	8 5	. 7	1 2
-	0 0	. 0	1 4
	2 5	. 0	4
-
	5 0	. 0	1:
-	6 2	. 5
	7 5	. 0	13
-	8 7	. 5	14
-	0 0	. 0	1 6
-	2 2	. 2
-	4 4	. 4	ii
	5 5	. 5	1 0
-	6 6	. 7	12
-	8 8	. 8	1 6
	‘00.0		18
-	2 0	. 0	4
-	4 0	. 0	a
	5 0	. 0	10
	6 0	. 0	12
-	7 0	. 0	1 4
	80.0		1 6
t	9 0	. 0	1 8
	100.0		2 0
-	18	.2 4
	3 6	. 3
-	4 5	. 4	1:
	5 4	. 5	1 2
-	63	.6	1 4
4	72	.7	16
	9 0	. 9	2 0

4t 00.0 2 2

-

-16.6 4

-3 3 . 3 a

4 1 . 6 1 0

-50.0 1 2

6 6 . 7 1 6

-7 5 . 0

9 1 . 6 :;

:100.0 2 4

-

19.04

-	3 8 . 0	8
	4 7 . 6
	5 7 . 0	iif
-	6 9 . 0
	7 8 . 6	::
	9 0 . 4	2 2
E	100.0	2 4
-

B2

-

-

-

-

-

-

-

-

-

-

-

4

4

:

-

4

4

4

4

-

-

:

6

6

-

-

-

:

E

-

(NOTE: The control circuit power must be on at all times even when the main unit power is off.)

Start-Up- When the RUN/STANDBY switch is moved from the STANDBY to the RUN position and there is a call for cooling, after l-l /2 to 3 minutes have passed the first compressor will start unloaded, The first circuit to start may be circuit A or B due to the automatic lead/ lag feature.

Capacity Control - (See Table 4.) The rate at which the compressors are turned on will depend on the leaving water temperature difference from the set point, the rate of change of leaving water temperature, the return water temperature and the number of compressor stages on. The control is primarily from leaving water temperature and the other factors are used as compensation.

SEQUENCE -- On a caiI for cooling, the controI system starts the initial compressor. The control will randomly select either circuit A or B. The liquid line solenoid valve remains closed for 10 seconds after the initial compressor on that refrigeration circuit starts. This permits a pump- out cycle at start-up to minimize refrigerant floodback to the compressor. If the compressor in that refrigeration circuit has run in the 15 minutes before the call for cooling, the pumpout cycle is bypassed.

After pumpout, the liquid line solenoid valve opens and the electronic expansion valve starts to open.

The electronic expansion valve will open gradually to provide a controlled start-up to prevent liquid floodback to the compressor. Also during this period, the oil pres- sure switch will be bypassed for one minute.

As additional cooling is required, the control system will ramp up through the capacity steps available until the load requirement is satisfied. As capacity steps are added compressors are brought on line, alternating between the lead and lag refrigerant circuits. As explained previously, the speed at which capacity is increased or decreased is controlled by the temperature deviation from the set point and the rate of change in the chilled water

NOTE: Circuits and compressors designated from ieft to right when viewed from front of unit.

temperature.

4