Demand Control; Contact Input And Control Content - Mitsubishi Electric PURY-P72 Service Handbook

[ 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 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).
No Demand control switch
1 2 steps (0-100%)
2
4 steps (0-50-75-100%)
3
8 steps
4
(0-25-38-50-63-75-88-100%)
*1 Available demand functions
P72-P144T(Y)JMU-A models (single-outdoor-unit system) : 2 and 4 steps shown in the rows 1 and 2 in the table above only.
P168-P288T(Y)SJMU-A models (two-outdoor-unit system OC+OS) : 2-8 steps shown in the rows 1, 2, 3, and 4 in the table
above only.
*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% 0% 50% The units may go into the Thermo-OFF mode.
(Correct) 100% 75% 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.
ŒPerforming 4-step demand in combination with the low-noise operation in a single-outdoor-unit system.
ŒPerforming 8-step demand in combination with the low-noise operation in a two-outdoor-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
1-3
Open
Close
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
8-step demand control (When SW4-4 is set to ON on two outdoor units)
Demand capacity is shown below.
8-step demand
No.1 CN3D 1-2P
Open
Short-circuit
*1. The outdoor units whose SW4-4 is set to ON are designated as No. 1 and No. 2 in the order of address from small to large.
Ex) When outdoor units whose SW4-4 is set to ON are designated as OC and OS, OC=No. 1 and OS=No. 2.
HWE09130
DipSW4-4
OC
OFF OFF
ON OFF
OFF
ON
100%
0%
1-2P
Open Close
100% 75%
0% 50%
1-2P
1-3P Open
Open 100%
Short-circuit 50%
Open 88%
Short-circuit 75%
- 25 -
2
Input to CN3D*
OS
OC
OC
ON OS
ON OC and OS
No.2 CN3D
Open
Short-circuit
50% 88%
0% 38%
38% 75%
25% 63%
Short-circuit
Open Short-circuit
75%
25%
63%
50%
GB