Samsung Electronics 228
Piping Diagram
Low Pressure Protection
ƒ Purpose
Prevent abnormal low pressure to protect the system and compressors.
ƒ Concept
The compressor operation frequency is lowered to increase the low pressure.
The Hotgas Bypass Valve is opened to bypass the high pressure
to the suction pipe. This will increase the low pressure.
ƒ Control specification in detail (Cooling mode)
- Control of the operation frequency (see the chart in the previous page for pressure conditions.
)
∙ 1st step Hz hold : Fix the current frequency if the discharge temperature is higher than 70ఁ .
(It is possible to lower the frequen
cy)
∙ 2nd step Hz down : Automatically lower the frequency by 5Hz at specified intervals if the discharge temperature is higher than
70ఁ .
∙ 3rd step HP down : Automatically lower the frequency by 1Hz every second if the discharge temperature is higher than 70ఁ .
∙ 4th ste
p Comp trip : If in critical state for 3 min, stop the compressors and trigger an error (E410).
- Control of the Hot Gas Bypass Valve
Open the valve if low pressur
e is 3.2kgf/cm2,g.
Close the valve if low pressure is 4.2kgf/cm2,g.
- Others
If the water temperature is abnormally low, limit opening of the valve.
This reduces the need to repeatedly turn on the low pres-
sure protective control.
When cooling mode is on and the water temperature is 25ఁ or
lower, one of the Hz Hold through HP Down steps is activated if
the low pressure is -1kgf/cm2,g.
ƒ Control specification in detail(Heating mode)
- 1st step Hz Hode : Fix the current frequency
- 2nd st
ep Hz down : Automatically lower the frequency by 5hz at specified intervals
- 3rd step HP down : Automatically lower the frequency by 1hz every s
econd
- 4th step Comp trip : low pressure is less than 2.6 after HP down control entry 1min(in case of water circulation)
- Control of the Hot Gas Bypass Valve(in
case of water circulation).
Open the valve if low pressure is 7.5 or lower.
Close the valve if low pressure is 9.5 or higher.
7-3 Functions (cont.)
7-3-2-5 Protective control (cont.)
7-3-2 Control (cont.)
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