Daikin R407C PLUS Service Manual page 90

Si33-105
3.5.4 Inverter Protection Control
Controls the compressor upper-limit frequency to prevent tripping by inverter overcurrent and fin
temperature increase.
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3.5.5 High Pressure Protection Control
The following control is provided for the compressor operating frequency and others to prevent
protection devices from malfunctioning due to abnormal increase of high pressure (HP) and to
protect the compressors.
[Cooling and simultaneous cooling / heating operation mode]
[Oil return mode (common for cooling / heating)]
Outdoor unit fan and hot gas bypass solenoid valve (SVP) under oil return operation are
controlled not to actuate high pressure protection. Also outdoor fan is controlled to protect short
refrigerant circulation due to low high pressure during low ambient temperature. (Oil returning is
hard at short refrigerant circulation)
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Function R407C PLUS Series Heat Recovery System
• Inverter current > 30A±5%
OR
• INV fin temp. > 92˚C
Normal operation
• Compressor stop
OR
• Upper limit frequency= Max. frequency
1: Upper limit frequency according to "step down control".
HP ≥ 2.45MPa
1 step down for upper limit
Normal
compressor operation frequency
0
operation
Judge every 10 sec, and down
1 step until HP<2.45MPa
• Heating operation
OR • Compressor stop
1 step increase for compressor
operation frequency
Upper limit frequency
= Max. frequency
HP<1.72MPa
Step1
SVP : ON
Fan : Step
HP>2.16MPa
Movement
Step SVP
"
ON
OFF
OFF
SVP of turns ON only when heating mode.
The step 1, 2 and 3 will be cancelled when the oil return operation is completed.
Refer p.96 for Fan step table.
Outline of Control (Outdoor Unit) < Symbols using in this manual >
Lowering upper limit
frequency for -step
(every 10 sec)
Retry
HP ≥ 2.81MPa
HP < 2.16MPa
HP ≥ 2.45MPa
&
Continues 30 sec.
HP<1.49MPa
Step2
SVP : OFF
Fan : Step
HP>1.79MPa
Fan
Step
Step
Step
• Inverter current ≤ 30A±5%
• INV fin temp. < 87˚C
OR
• 3-min elapse
Raising upper limit
0
1 frequency for -step
(every 3 min)
HP > 2.94MPa
Forced
thermostat OFF
Up to 2 times
within 30 min
HP < 2.35MPa
&
OR
Continues 5 min.
Step3
SVP : OFF
Fan : Step
(V0825)
0
1
(V0832)
E3 normal
stop
(V0823)
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