Mitsubishi Electric PQHY-P72TYHMU-A Service Handbook page 33

[ II Restrictions ]
(8) Demand control
1) General outline of control
Demand control is performed by using the external signal input to the 1-2 and 1-3 pins of CN3D on the heat source units (OC,
OS1, and OS2).
Between 2 and 12 steps of demand control is possible by setting DIP SW4-4 on the heat source units (OC, OS1, and OS2).
Table.1
No Demand control switch
(a) 2 steps(0-100%)
(b) 4 steps(0-50-75-100%)
(c)
(d)
(e) 8 steps(0-25-38-50-63-75-88-100%)
(f)
(g)
(h) 12 steps(0-17-25-34-42-50-59-67-75-
84-92-100%)
P200-P300YHM models (single-heat source-unit system): 2 and 4 steps shown in the rows (a) and (b) in the table above
only.
P400-P600YHM models (two-heat source-unit system OC+OS1): 2-8 steps shown in the rows (a), (b), (c), and (e) in the
table above only.
P650-P900YHM models (three-heat source-unit system OC+OS1+OS2): 2-12 steps shown in the rows (a)-(h) in the table
above.
*2. External signal is input to CN3D on the heat source unit whose SW4-4 is set to ON. When SW4-4 is set to OFF on all heat
source units, the signal is input to the CN3D on the OC.
Heat source units whose SW4-4 is set to ON are selectable in a single refrigerant system.
*3. If wrong sequence of steps are taken, the units may go into the Thermo-OFF (compressor stop) mode.
Ex) When switching from 100% to 50%
(Incorrect) 100% to 0% to 50% : The units may go into the Thermo-OFF mode.
(Correct) 100% to 75% to 50%
*4. The percentage of the demand listed in the table above is an approximate value based on the compressor volume and
does not necessarily correspond with the actual capacity.
*5. Notes on using demand control in combination with the low-noise mode
To enable the low-noise mode, it is necessary to short-circuit 1-2 pin of CN3D on the heat source unit whose SW4-4 is set
to OFF.
When SW4-4 is set to ON on all heat source units, the following operations cannot be performed.
ŒPerforming 4-step demand in combination with the low-noise operation in a single-heat source-unit system.
ŒPerforming 8-step demand in combination with the low-noise operation in a two-heat source-unit system.
ŒPerforming 12-step demand in combination with the low-noise operation in a three-heat source-unit system.
2) Contact input and control content
2-step demand control
The same control as the Thermo-OFF is performed by closing 1-3 pin of CN3D.
CN3D
1-3P
Open
Close
4-step demand control (When SW4-4 is set to ON on an heat source unit)
Demand capacity is shown below.
CN3D
1-3P
Open
Close
HWE09080
DipSW4-4
OC OS1
OFF OFF
ON OFF
OFF
OFF OFF
ON
ON OFF
OFF
ON
x = 100%
x = 0%
1-2P
Open
100%
0%
- 24 -
Input to CN3D *2
OS2
OFF OC
OFF OC
ON OFF OS1
ON OS2
ON OFF OC and OS1
ON OC and OS2
ON ON OS1 and OS2
ON ON OC, OS1, and OS2
Close
75%
50%
GB