Special Controls - Panasonic U-4LE1E5 Service Manual

3. Special Controls

3. Special Controls

In addition to ordinary heating and cooling operation, this system also includes the following 4 types of special
controls for control of the system as a whole:
3-1. Oil discharge prevention device control
3-2. Reverse cycle start control
3-3. Inter systems refrigerant oil recovery control
1
3-4. Reverse cycle defrost control
3-1. Oil discharge prevention device control
Perform an oil discharge prevention control when starting from the stop mode.
• When starting the operation after a long hour-stop mode under a low outdoor air temperature,
control the oil discharge prevention without rapidly increasing the compressor's frequency to avoid draining
the condensed refrigerant together with oil until the overheating inside the compressor is decreased.
• In order to judge as to whether the compressor is to be started when in a high temperature state,
a starting pattern will be changed according to the discharge temperature.
(1) Control in the Cooling Mode
Control hour
Outdoor unit Compressor
Fan
Indoor unit
Elec. cont. valve* 4
NOTE
*1 Td: Discharge temperature
*2 HPT: High pressure saturated temperature
*3 K: Difference in temperature (1K=1°C)
*4 Elec. cont. valve: Electronic control valve
Min. 1 minute to Max. 5 minutes
(Discharge degree-of-overheating: Td* 1 - HPT* 2 > 10K* 3 )
Frequency 22Hz (Max. 3 minutes) → Without constraint
Thermostat ON
Cooling
Thermostat OFF
Preset wind speed
Fan
OFF OFF
Thermostat ON
SH (super heat) control
Cooling
Thermostat OFF
20 pulse
Fan
20 pulse
OFF
20 pulse
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Mini VRF SYSTEM
Mini VRF SYSTEM
Control Functions
Control Functions