SiUS181631EA Branch Provider (BP) Unit Control
Functions and Control 69
6.2 Branch Provider (BP) Unit Electronic Expansion Valve
Control
This function provides instructions regarding the absolute flow rate, relative flow rate and fully
closing from the outdoor unit to the BP unit in order to ensure outdoor unit compressor safety and
optimum refrigerating cycle of the system.
With the transmission a permit/prohibit flag for each distribution control in the BP unit, the
distribution control startup timing is controlled by the outdoor unit.
6.2.1 Electronic Expansion Valve Initial Opening Setting
Outline This function improves stability of the system to set initial opening of the electronic expansion valve
at starting operation.
When the EV opening command from outdoor unit is lifted, the following opening setting is
performed.
Details Cooling Operation
Tr: room thermistor temperature
Ta: outdoor temperature
Heating Operation
Target opening = 350 pulse
6.2.2 Electronic Expansion Valve Flow Rate Restriction
Outline This function prevents deviation from the specified electronic expansion valve range by restricting
the electronic expansion valve flow rates of the operating and non-operating indoor units during
compressor operation. It also prevents the generation of abnormal noise such as refrigerant flowing
sound by restricting the circulation of refrigerant according to the operating conditions (unit ON/
OFF) of indoor units.
Details Restriction of electronic expansion valve opening degrees of operating indoor units;
... Restriction of maximum and minimum flow rates based on constant
Restriction of electronic expansion valve opening degrees of non-heating indoor units;
... Restriction of minimum flow rate based on constant
... Maximum flow rate determined based on flow rates of operating indoor units
AB
07 ~ 12 class 140 Ta
≤
Tr 0
15 ~ 18 class 156 Tr
<
Ta 2.5
24 class 170
5
2
25
18
286
5
5
9
Target opening (pulse) = × (Tr (˚C) – 14) + A – B × (Ta (˚C) – Tr (˚C))
= × (Tr (˚F) – ) + A – B × × (Ta (˚F) – Tr (˚F))
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