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8.2 Protection Function Summary
・ Protection Controls varies by Outdoor unit, please see appropriate Outdoor unit service manual for full details
(Below "Protection Function Summary" is according to SMMS-u.)
Function
Freeze prevention control
In Cooling Mode prevents low DX-COIL temperatures by controlling compressor speed
(Low temperature release)
(based on TC1/TC2/TC sensor temperature).
Cooling oil (refrigerant)
This control periodically increases flow-rate to ensure refrigerant oil does not build up
recovery control
in inter-unit gas pipes (which can occur when operating command is inadequate,
or while cooling is progressed under low ambient conditions).
During this control the compressors are operated at a target speed, and Dx valve kit
PMV is opened to a certain degree. Upon completion of recovery control normal
Cooling operation resumes.
Heating refrigerant (oil)
This control periodically increases flow-rate to ensure liquid refrigerant trapped inside
recovery control
the DX COIL. It also serves the purpose of recovering DX COIL / Outdoor refrigerant
(Heating Start up Control)
after defrosting and recovering oil present in outdoor heat exchangers during heating
overload operation.
During this control the compressors are operated at a target speed, and Dx valve kit
PMV is opened to a certain degree. Upon completion of recovery control normal Heating
operation resumes. Recovery operation normally takes place after defrosting.
Defrost control
In Heating mode a defrost operation can be performed to reduce ice build-up on the
(Full Defrost)
Outdoor unit (based on TE1 & TE2, TE3 sensor). During Defrosting the refrigerant cycle is
reversed temporarily cooling the DX COIL.
During the heating operation, if the TE sensor detected temperature falls below the predicted
TE sensor temperature by a specified amount, or if the TE sensor detected temperature falls
below the frosting temperature for 300 minutes, the defrosting operation starts.
(After start-up or when switching from cooling to heating, frost judgment is performed and the
defrosting operation is started according to the judgment result.)
While the outdoor unit is Defrosting the Dx valve kit PMV is opened to a certain degree.
Heating Recovery operation normally takes place after defrosting.
* In the case of the coupled system, when any of the outdoor units satisfies the defrosting
start condition, all the units in the group to which the unit belongs start defrosting operation,
and the other Gr units continue heating operation.
High Pressure release
This control function is aimed at automatically shutting down a compressor in an outdoor unit
control
depending on Pd. It is individuality performed by the header unit and each follower unit.
• Compressors are shut down when Pd reaches or exceeds P0
• The Pd control point P0 is switched according to the start priority of the outdoor unit
• The compressor restart prevention timer (2 minutes 30 seconds) is set, and the controlterminated.
Case Heater control
There are 1 types of case heater: a compressor case heater.
This control function is aimed at preventing the accumulation of refrigerant in those case,
and is performed by all outdoor units.
If the power supply has not been turned on for a specified period before a post-installation
test run. Compressor failure may occur.Similarly, when starting compressors after a long period
of no power supply, it is recommended that the power supply be turned on for a while before
operation is resumed, just like a post-installation test run.
IPDU control
(1) Current, power release value control
(IPDU =
The purpose of this control is to prevent high pressure rise and overheating of electric
Inverter P.C. board
parts by reducing the compressor speed when the maximum current and maximum
for compressor )
power value set for each model are exceeded.
(2) Heat sink overheat abnormality
• Stop the compressor operation when the TH sensor temperature exceeds 93°C.
• When the above is stopped, the abnormal count is set to 1, and it restarts after 2 minutes
and 30 seconds.If you continue the operation for 10 minutes or more after restarting,
the trouble count will be cleared.
• A trouble is confirmed with a trouble count of "4".(error code P07).
(3) High pressure SW control
Inverter compressor stops driving the compressor when the high pressure SW is operating.
• When the above is stopped, the abnormal count is set to 1, and it restarts after 2 minutes
and 30 seconds.If you continue the operation for 10 minutes or more after restarting,
the trouble count will be cleared.
• The trouble count becomes "4" and the trouble is confirmed.(error code P04).
Summary
P42
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