Service manual

16 Siemens-Elema AB E382 E380E 061 01 03 01
Introduction Servo Ventilator 300/300A
1
In addition to the main forward path,
compensating elements are added as
described in both inspiratory feedback
control system pictures. The compensating
elements in this system works as follows:
• Using the input information of ACTUAL
SUPPLY
PRESSURE VALUE and DESIRED GAS FLOW
VALUE
the VALVE POSITION CALCULATOR directly
generates a rough approximate POSITION
VALUE
which helps to obtain the desired
position within minimum time.
• The input information of ACTUAL SUPPLY
PRESSURE
VALUE is used (inverted and
adequatly scaled) to create one small part
of the DESIRED CURRENT VALUE. This small part
of the DESIRED CURRENT VALUE will – in
combination with the opening force of the
INSPIRATORY VALVE implied by the pressure of
the supplied gas – help to balance the
closing force on the INSPIRATORY VALVE
implied by the mechanical spring inside
the VALVE SOLENOID even in closed position
of the INSPIRATORY VALVE.