Mitsubishi Heavy Industries SRK25GZ-L1 Handbook page 200

SCM-HG (2 room)
(9) Control and protection functions
(a) Start of protection for compressor
When the decision speed becomes a speed other than 0 rps and when the compressor is starting operation, an inverter
decision speed of 40 rps or less indicates four-way valve switching protection and a speed of 40 rps or more indicates that
protection of the compressor has started.
1) Start of protection for compressor
a) After the compressor has started, the speed of the outdoor unit will reach a maximum value of 56 rps for 1 minute
and 45 seconds.
b) During this time, if the decision speed exceeds 56 rps, operation will be at 56 rps; if it is 56 rps or less, operation will
be at the decision speed or operation with four-way valve switching protection.
c) The outdoor unit fan speed operates according to outdoor unit speed.
d) If restarting after a thermostat stop, the protection function for the outdoor unit operates and when restarting after
the inverter stop, compressor protection is not started.
e) During the start of protection, current safe and compressor overheat have priority.
2) Four-way valve switching protection
Four-way valve switching protection is performed so that four-way valve switching will be performed smoothly.
a) When the decision speed starts at less than 40 rps, it forces the decision speed to operate at 40 rps for 30 seconds.
b) After 30 seconds, the speed of the outdoor unit is transferred to the decision speed.
c) This function applies to all units starting from an outdoor unit speed of 0 rps.
d) Current safe and compressor overheat protection are enabled even when this function is in operation.
(b) Heating overload protection control
During heating operation, if the outdoor unit is operating at a speed at 28 rps or more and the outdoor temperature is 12 °C or
more for 30 continuous seconds, current safe control is performed.
Operation is restored when the outdoor temperature is 10 °C or less.
(c) Cooling overload protection control
During cooling operation, if the outdoor unit is operating at a speed at 28 rps or more and the outdoor temperature is 39 °C
or more for 3 continuous minutes, current safe control is performed by turning the outdoor fan dial up by 1 unit. Operation is
restored when the outdoor temperature is 38 °C or less.
(d) Heating thermostat OFF control
When there is a heating operation being performed for one room while a heating thermostat OFF is being performed in
another room, the following controls are performed to prevent overheating.
1) This control is performed when all of the following conditions have been satisfied.
a) Compressor: During operation (determined speed 28 rps or more)
b) One room serial signal: Operating mode – heating, command speed: other than 0 rps.
c) Other room serial signal: Operating mode – heating, command speed: 0 rps.
2) Description of control
Functional components
Outdoor unit speed
Actual operating speed
Outdoor unit fan
EEV AB Operating
unit compatible
EEV AB Heating
0 rps compatible
198
Operation of each functional components
Decision rps
Decision rps
According to
outdoor rps
58 pulse
Fully closed
4 min
Start of control
Remarks
Release of control