Terumo BCT Trima Accel, Руководство по обслуживанию

Страница: 73 / 340

Figure 2-10: Level sensor block diagram
The safety CCA sends out a bang and then listens for the return every 250 microseconds. The safety
CCA automatic gain control (AGC) circuitry increases gain as the fluid in the reservoir decreases,
because the signal transmits more easily through fluid in the reservoir than through air. As the fluid level
in the reservoir increases, the gain decreases, and vice versa. The bang generated from the safety CCA
waits for the control CCA to trigger it. The safety CCA splits off the listen signal to both control and
safety systems. The signal comparison happens on the safety CCA.
If the lower-level sensor sees air, this is a bad safety condition. If this occurs, the safety system removes the
control system’s command ability by removing the 24 volts.
Donor safety: During a return cycle, if the lower-level sensor detects air too early or too late, the safety
system removes the 24 volts to the motor driver CCA, which removes pump power so the pumps do not
run even if commanded to do so by the control system. This prevents air from being returned into the
donor.
System Description
2-12 Trima Accel
®
Automated Blood Collection System • Service Manual