Mitsubishi Electric PQHY-P72ZLMU-A Service Handbook page 35

[ 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 SW6-8 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%)
*1. Available demand functions
P72-P240TLMU/YLMU models (single-heat source-unit system): 2 and 4 steps shown in the rows (a) and (b) in the table
above only.
P144-P360TLMU/YLMU 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.
*2. External signal is input to CN3D on the heat source unit whose SW6-8 is set to ON. When SW6-8 is set to OFF on all heat
source units, the signal is input to the CN3D on the OC.
Heat source units whose SW6-8 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 SW6-8 is set
to OFF.
When SW6-8 is set to ON on all heat source units, the following operations cannot be performed.
Performing 4-step demand in combination with the low-noise operation in a single-heat source-unit system.
Performing 8-step demand in combination with the low-noise operation in a two-heat source-unit system.
Performing 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 SW6-8 is set to ON on an heat source unit)
Demand capacity is shown below.
CN3D
1-3P
Open
Close
HWE15150
DipSW6-8
OC OS1
OFF OFF
ON OFF
OFF
OFF OFF
ON
x = 100%
x = 0%
1-2P
Open
100%
0%
- 26 -
Input to CN3D *2
OS2
OFF OC
OFF OC
ON OFF OS1
ON OS2
ON OFF OC and OS1
Close
75%
50%
GB