Daikin LX10F11B3 Service Manual Download

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1-16

1.4.6 Common Control

●

Compressor running control

Compressor changes speed Min. 20 rps to Max.
130 rps with inverter control.

①

Start up control

③

Pull down control

⑤

Modulation

Compressor

Time

Max.

130 rps

Min.

20 rps

②

Step up control

④

Step down control

Cooling OFF

RS or SS

Unit ON

Approx.

67 rps

①

Start up control

After unit switch ON, unit goes to calibration valves
at first and compressor start up control. Start up
control is to protect liquid back condition due to unit
stops for long time under low ambient temperature.
It is controlled with three steps: (1) pump down
operation, (2) operation not in wet conditions 1,
(3) operation not in wet conditions 2. Although it
normally completes in several minutes, sometimes
it takes almost 20 minutes if totalizing the time of
guard timer at each step.

②

Step up control

After completion of start-up control, the rotation
speed will increase to the maximum speed of the
pull down operation by having a few steps. It takes
approximately two minutes.

③

Pull down control

It runs at the maximum rotation speed (130 rps)
during pull down. When some cause makes the
protection control activated, the rotation speed may
decrease, giving a high priority on the protection control.

④

Step down control

When the control temperature RS (frozen) or SS
(chilled) reaches the setpoint temperature SP, the
rotation speed of the compressor will be slowed
down gradually. It takes two to three minutes.

⑤

Modulation

When the control temperature RS or SS reaches SP,
the modulated control starts, and the compressor
controls rotation speed in response to temperature

difference between RS (or SS) and SP. (at the
speed of as low as 20 rps)
The compressor stops at small heat load condition.

●

Calibration valves

Turning the unit switch into ON triggers initial
operation for calibrating valves EEV, EMV, and DMV.
EEV and EMV are fully opened (420pls) then fully
closed (0pls). DMV is fully opened (760pls), then
fully closed (0pls) and fully opened (760pls) again.
The change of valve opening can be checked on
the LCD screen. Operate keys immediately when
the operation screen is displayed. The operation of
the modulation valve coils can be checked during
maintenance. (Refer to

※

3 Sensor information in

paragraph 2.3.)

●

Compressor protection control

When an operating status phenomenon is
detected, rotation speed of the compressor will
gradually slow down to protect the compressor. It
will resume to normal operation when the operation
status returns to normal. Three examples follow.
1. Suppression control of high-pressure increase

starts at HPT

≧

2110kPa.

2. Suppression control of low-pressure decrease

starts at LPT

≦

-50kPa.

3. Suppression control of discharged-gas-

temperature increase starts at DCHS

≧

117

℃

●

High pressure control

When ambient temperature is low, the high pressure
will decrease. Accordingly, the low pressure will
decrease too. In order to prevent this situation,
optimum pressure is maintained by switching the
condenser fan between OFF

⇔

Low speed

⇔

High

speed based on the high pressure value.

High Speed

Low Speed

OFF

HPT<800kPa

HPT>800kPa

HPT>1000kPa

HPT<600kPa