Mitsubishi Electric PFAV-P250VM-E Service Manual page 33

[ II Restrictions ]
3. 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 outdoor units (OC and
OS).
Between 2 and 8 steps of demand control is possible by setting DIP SW4-4 on the outdoor units (OC and OS).
Table.1
No Demand control switch
(a) 2 steps(0-100%)
(b) 4 steps(0-50-75-100%)
(c)
(d) 8 steps(0-25-38-50-63-75-88-100%)
*1. Available demand functions
P250YJM model (single-outdoor-unit system): 2 and 4 steps shown in the rows (a) and (b) in the table above only.
P500, P750YSJM models (two-outdoor-unit system OC+OS): 2-8 steps shown in the rows (a), (b), (c), and (d) in the table
above.
*2. External signal is input to CN3D on the outdoor unit whose SW4-4 is set to ON. When SW4-4 is set to OFF on all outdoor
units, the signal is input to the CN3D on the OC.
Outdoor 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 outdoor unit whose SW4-4 is set to
OFF.
When SW4-4 is set to ON on all outdoor units, the following operations cannot be performed.
Performing 4-step demand in combination with the low-noise operation in a single-outdoor-unit system.
Performing 8-step demand in combination with the low-noise operation in a two-outdoor-unit system.
(2) Contact input and control content
1) 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
2) 4-step demand control (When SW4-4 is set to ON on an outdoor unit)
Demand capacity is shown below.
CN3D
1-3P
Open
Close
HWE10190
DipSW4-4
OC
OFF
ON
OFF
ON
x = 100%
x = 0%
1-2P
Open
x = 100%
x = 0%
Input to CN3D *2
OS
OFF OC
OFF OC
ON OS
ON OC and OS
Close
x = 75%
x = 50%
- 24 -
GB