User manual

2920 1475 00
7
Instruction book
PT 1000 thermal protection
The PT 1000 thermal protection provides protection of the drive
motor. Five sensors are installed in the motor, two to measure
the temperature of the bearings and three to measure the
temperature of the windings. The readings can be called up on
the display of the Elektronikon regulator. A message will appear
on the display and the general alarm LED will light up if one of
the temperatures exceeds the shut-down warning setting. If
the temperature rises above the shut-down setting, the
compressor will shut down and the general alarm LED starts
blinking.
DIN/BSP or ANSI/NPT connections
For GA90 up to 160 a BSP or NPT connection can be chosen.
For GA200 up to 315 a DIN or ANSI connection can be chosen.
HD Roto-fluid
Special oil for Atlas Copco GA oil-injected screw compressors.
It provides better cooling and extends the oil change interval
to 8000 hours.
Cooling air outlet ducting
Diverts the cooling air in such a way that the hot air is not led
to the cooling air inlet. This option is only available for air-
cooled compressors.
Lifting device
The lifting device is a solid steel beam construction bolted to
the compressor. It allows the customer to lift the compressor
by means of e.g. a crane.
It is AIB and CE approved and complies with all applicable
safety standards.
1.2 Air flow / regulating system (Figs. 1.7
and 1.8)
1.2.1 Air flow 1)
Air drawn through filter (1) and unloader (2) is compressed in
compressor element (14). Compressed air and oil are
discharged through check valve (16) to air receiver/oil separator
(17) in which the oil is separated from the compressed air. The
air is blown through minimum pressure valve (19) to air cooler
(4). The cooled air is discharged through condensate trap (28)
and outlet valve (27) towards the air net.
Check valve (16) prevents blow-back of compressed air.
Minimum pressure valve (19) prevents the receiver pressure
from dropping below a minimum pressure. The valve has a
built-in check valve.
1.2.2 Condensate drain system
A condensate trap (28) is installed downstream of the air cooler
to prevent condensate from entering the air outlet pipe. The
trap is provided with a float valve for automatically draining
condensate and with a manual drain valve.
Full-feature compressors, which are provided with an air dryer,
have a second condensate trap downstream of the dryer. This
trap is also provided with a float valve for automatically draining
condensate and with a manual drain valve.
1.2.3 Oil system 1)
Air pressure forces the oil from receiver (17) through oil coolers
(6), filters (7) and oil stop valve (15) to compressor element
(14) and the lubrication points.
Oil stop valve (15) prevents the compressor element from
flooding with oil when the compressor is stopped.
Valve (26) by-passes oil coolers (6) when starting the
compressor from cold condition, to ensure rapid warming of
the oil to normal working temperature.
In air receiver (17) most of the oil is removed from the air
centrifugally. Almost all of the remaining oil is removed by
separator element (18).
1.2.4 Cooling system
On GA, the system includes air cooler (4) and oil coolers (6),
cooled by one or two fans (5) 2).
GA W are provided with a cooling water system, including a
combined oil and air cooler.
1.2.5 Regulating system
The system keeps the net pressure within programmable
pressure limits by automatically loading and unloading the
compressor depending on the air consumption. It is controlled
by Elektronikon
®
regulator (E1) which also protects the
compressor and monitors components subject to service. See
section 1.3.
1.2.5.1 GA/GA W 90/160
Unloading
If the air consumption is less than the air delivery of the
compressor, the net pressure increases. When the net pressure
reaches the upper limit of the working pressure (unloading