Service manual

2
Servo Ventilator 300/300A Description of functions
E382 E380E 061 01 03 01 Siemens-Elema AB 73
15.3 O
2
concentration amplifier
This block, the O
2
CONCENTRATION AMPLIFIER,
amplifies the signal from 11.3 O
2
CELL.
The output signal is amplified to 90 mV/%O
2
at 1013 mbar (760 mmHg) ambient
barometric pressure. This output signal is
used in:
•4 MONITORING to monitor the O
2
concen-
tration where it is distributed to 1.5 O
2
CONCENTRATION to display the measured
value on the front panel.
• 18.1 LINEARIZING CPU for compensation of
the EXP. FLOW value.
15.4 Valve zeroing
Zero offset is handled through:
• Timing control for the zeroing of the actual
gas flow and position signals within the
main blocks 8 INSPIRATORY VALVE UNIT – AIR
and 9 INSPIRATORY VALVE UNIT – O
2
when the
real actual gas flow is zero (normally
during pause time).
• Timing control for the zeroing of the actual
position signal within the main block 16
EXPIRATORY VALVE.
The timing control mentioned above is
executed in cooperation with the block 15.5
VALVE ENABLING.
15.5 Valve enabling
Valve enabling/disabling is handled through:
• Timing control (enabling) of the main
blocks 8 INSPIRATORY VALVE UNIT – AIR and
9 INSPIRATORY VALVE UNIT – O
2
.
• Timing control (disabling) of the main block
16 EXPIRATORY VALVE.
15 Valve control
This main block consists of the board
PC 1622 VALVE CONTROL.
15.1 PEEP PID control
Controller block comparing actual EXP.
PRESSURE signal from the main block 13
EXPIRATORY PRESSURE with desired PEEP LEVEL
signal according to front panel setting.
In order to somewhat decrease the
expiratory resistance at high expiratory
flows, the EXP. FLOW signal from the block
18.5 GAS COMPOSITION COMPENSATION is used in
addition to the actual EXP. PRESSURE value in
such a way that a high EXP. FLOW value results
in a somewhat bigger opening of the
EXPIRATORY VALVE compared to when the EXP.
FLOW value is small.
The actuating output signal is used as a
desired POSITION REF signal for the block 15.2
POSITION PD CONTROL.
15.2 Position PD control
Controller block comparing actual EXP. VALVE
POSITION
signal from the block 16.3 EXPIRATORY
SOLENOID
WITH POSITION SENSOR with desired
POSITION REF signal from the block 15.1 PEEP
PID
CONTROL. The actuating output signal is
used as desired EXP. VALVE CURRENT REF for the
block 16.1 CURRENT CONTROL.