AGL_HA_ST_Discus_A2L_A1_EN_Rev00 7
Usually, the unloaded start is activated once for about 5-10 seconds shortly before compressor start
and then kept closed during operation. The unloaded start solenoid valve opens a suction channel
in the valve plate and the pressure in the discharge line equalizes to the suction side.
Assembly
Installation of the modified cylinder head and valve plate for unloaded start is only possible at certain
positions on the compressor. Therefore all 8D* compressor models have fixed cylinder head
positions for unloaded start.
Figure 6: Unloaded start position for 8D* models
2.5.5 Capacity control
Ignition source in a potentially flammable atmosphere! Fire hazard! The
solenoid valve of the capacity control is not an ignition source during normal
operation in an A2L-refrigerant system but could become one if not installed
properly. Never operate the solenoid coil when not positioned on the solenoid
valve. Secure the installation with a screw.
A mechanical capacity control is available for 8D* compressors. The system used is blocked suction.
The suction port of the valve plate will be closed by a control piston. When an 8D* compressor is
ordered with capacity control, it is equipped with one or two special cylinder heads. The capacity
control valves with coils are positioned on the top of the cylinder head. Not all cylinder bank positions
are possible for the capacity control cylinder head.
Capacity control must be fitted in the following positions:
8D* 1
st
step 25 % Lower cylinder head on terminal box side
8D* 2
nd
step 50 % Lower cylinder head on discharge valve side
Figure 7: Capacity control position on 8D* models
2.5.6 Oil pump
All 2D*, 3D* and 8D* compressors are equipped with an external oil pump. The oil pump will always
work in the correct direction of rotation, regardless of the rotation direction of the compressor. The
compressors are designed to accommodate fittings for an OPS2 oil safety system (OPS2 oil sensor
included in the oil pump) or any conventional oil pressure switch.
2.5.7 Oil pressure
Normal oil pressure is between 1 and 4.2 bar higher than crankcase pressure. Net oil pressure can
be read by connecting two pressure gauges to the compressor and comparing the readings. One
To Next Page
Loading...
Need help?
General
