Hitachi CA47TLA-D2PE3 Manual page 26

(3) Safety Device for Protection from High Pressure and Low Pressure
*Be sure to use a high-pressure switch or safety valve.
*Be sure to use a low-pressure cut switch.
*Considering the tolerance of the pressure switch, the device should be set to values so that
it can be within the operation pressure limits stipulated in Clause 6 "Working Range
(Pressure and Temperature)" of the specifications.
compressor should be stopped by the operation of the protective device.
(a) High pressure side: ≦ Upper limit for the discharge gas pressure
(b) Low pressure side: ≧ Lower limit for the suction gas pressure
*For the operating circuits of the protective device, be sure to use the manual recovery circuits.
However, this limitation may not be applied for short time (approx. 30 seconds or less)
operation, such as pull-down or starting operation.
*For the wiring of the pressure switch, refer to Clause 2 "Basic Electrical Wiring Diagram
(for 3 phase)."
*Even when a pressure transducer is used, it is recommended to install the high-pressure cut
switch.
(4) Configuration of the Refrigeration Cycle
The example of the configuration of the refrigeration cycle is shown in Clause 4.
*Accumulator
Install an accumulator in front of the refrigerant gas suction inlet of the compressor so as not to
draw the liquid refrigerants that do not evaporate with an evaporator to the compressor.
accumulator should have the capacity to contain 50% or more refrigerants of all the refrigerant
charged capacity. In addition, an oil return hole should have the appropriate sizes to carry
out oil return. Note that the capacity in this case should exclude the capacity of the delivery
tubes.
* Suction gas strainer
A suction gas strainer (around 100 mesh) should be equipped between the accumulator and
the compressor in order to protect against the entry of foreign particles from the cycle side into
the compressor.
* Oil separator
The minimum oil contained in the compressor may not be secured depending on the
configuration of the refrigeration cycle and the sizes of the heat exchangers. In this case, the
installation of an oil separator on the discharge side of the compressor is recommended to
maintain the minimum oil charge.
The oil return pipe from the separator shall be connected to the inlet side of the accumulator,
and the oil return pipe shall be capillary.
*Start bypass circuits
The installation of bypass circuits between the suction pipes and the discharge pipes is
recommended to reduce the time of balancing discharge gas and suction gas. The bypass
circuits should be set to be closed while the compressor is in operation.
If it exceeds the set values, the
7
The