Panasonic R410A Service Manual page 11

2. Compressor Control
2-3-2. Roadmap control in heating mode
Roadmap control is performed using the below condensation temperature control.
Condensation temperature (=Tc) control
(1) For indoor units that are operating in Heating mode, if one unit is selected for a test run, the air intake temper-
ature difference is ignored; however, Tc control is performed according to Fig. 1-3 in order to prevent excessive
load. (This is used for test run checks, etc.)
(2) Even within the same area, the compressor capacity varies depending on the refrigerant temperature.
(3) If the condensation temperature (Tc) enters area D and the thermostat turns OFF, the next time the compres-
sor starts it may restart from a lower capacity.
(4) When the area changes to area C, area C is considered to be area B for control purposes for the first 6 min-
utes, even if the horsepower is the minimum value within the range where capacity control is possible (opera-
tion with inverter frequency of 25 Hz only). Subsequently if C area continues, the thermostat turns OFF.
2-3-3. Protection control
Protection control consists of 2 types of protection: compressor air discharge temperature protection and current
protection. The limit values from this protection control are incorporated into the output compressor capacity
increase/decrease values that were calculated from roadmap control.
* In some cases, the control shown below may stop the compressor, issue an alarm, or reduce the compressor
capacity.
(1) Air discharge temperature protection
The compressor capacity is limited by using the air discharge temperature of the operating compressor (as
shown in the tables below).
(Air discharge temperature level: Highest level among the air discharge temperature levels of all compressors)
Air discharge
temperature level
221
219
215
210 – Less than 215
204 – Less than 210 Hp increase permitted (slowly)
Less than 204
The values shown in the table above are reduced to the
values calculated by roadmap control.
Thermostat OFF
133.7°F
133.5°F
Horsepower decrease
123.9°F
123.8°F
Horsepower increase prohibited
120.2°F
120.0°F
Horsepower increase permitted
Horsepower (hp) limits
+2 hp down
+1 hp down
+0.5 hp down
Hp increase prohibited
No restriction
(Area D)
(Area C)
(Area B)
(Area A)
Fig. 1-3
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Mini VRF SYSTEM
Control Functions
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