Outdoor Unit Control - Mitsubishi Electric PKA-RP1.6GAL Service Technical Manual

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8

OUTDOOR UNIT CONTROL

8-1. COOL operation
Control modes
1-1. Thermoregulating function
1. Compressor
1-2. Normal control
1-3. Start-up control
1-4. Indoor anti-freezing control
1-5. Indoor frozen prevention control
The outdoor unit receives information of set temperature and intake
temperature from the indoor unit through transmission and judges the
necessity of thermoregulating from their temperature difference.
(Refer to "INDOOR UNIT CONTROL" for detailed detecting method.)
Compressor operating frequency is controlled according to the difference
between intake temperature and set temperature in order to let the intake
temperature be the same as the set temperature
• Control timing: Once per minute after 3 minutes have passed since the
compressor started.
• Frequency changing range: -12Hz to +20Hz
w: However, in the following cases, the frequency changing amount, which is
different from the normal one, will be applied to control the operating frequency.
(1) Frequency is fixed to the minimum just before the compressor is stopped
by the thermoregulating function.
Intake temperature [ Set temperature +0.5: ··· Fixed to the minimum frequency.
Intake temperature [ Set temperature +1.0: ··· Fixation is released. (Returned to normal control.)
(2) Correction of the frequency changing amount according to the estimated
discharge temperature If the estimated discharge temperature is more than
113:, the frequency changing amount will be corrected.
• Correction amount: 0Hz to -6Hz
Controls, which are conducted in 3 minutes after the compressor gets started,
are categorized as below.
(1) In case of start-up (first time)
a. 0 min. to 1 min. after start-up: Fixed to 48Hz.
b. 1 min. to 3 min. after start-up: Fixed to the Hz which has been regulated
according to the temp. difference between intake temp. and set temperature
• Fixed frequency: minimum Hz to 48Hz.
(2) In case of restart
a. 0 min. to 1 min. after start-up: Fixed to minimum Hz.
b. 1 min. to 3 min. after start-up: Fixed to the Hz which has been regulated according
to the temperature difference between intake temp. and set temperature
• Fixed frequency: minimum Hz or 42Hz.
Maximum Hz will be controlled to 70Hz for 10 minutes after the start-up of compressor.
When the outdoor unit receives the signal of anti-freezing control mode, the
compressor stops. The compressor will restart when the indoor anti-freezing
control is released.
Frequency controls such as Hz-down and no more Hz-up will be conducted
according to the indoor liquid pipe temp. (TH2) or indoor cond./eva. temp. (TH5).
Temp. restriction: No more Hz-up ··· When TH2 or TH5 detects 4.5: or less
Hz-down
Control details
··· When TH2 or TH5 detects 3.5: or less W
W Hz-down amount: -5Hz per minute
47
Remarks
Refer to "8-7.
Inverter control"
for "Inverter
control basic
control
frequency
setting".
Refer to
"INDOOR UNIT
CONTROL" for
the indoor
anti-freezing
control.
Continued to the next page.

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