Chapter 3
3-8
BiPAP Vision Service Manual © Respironics, Inc.
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Theory of Operation
3.1.3
Overvoltage Disconnect
The overvoltage disconnect removes the DC supply output when it exceeds
36 VDC and reconnects the DC supply output when the level returns to an
acceptable value.
3.1.4
AC Fail Detection
The MC board monitors the level of DC supply voltage and the AC voltage
output from the transformer supply winding to determine if an AC fail
condition exists.
•
Low DC supply detect: if the DC supply voltage drops to 19.38 VDC or
lower (nominal), an AC fail condition is triggered.
•
Line loss detect: the AC voltage output from the transformer supply
winding is monitored for a loss-of cycle condition. Both legs of the
winding are input to the monitoring circuitry. Whenever AC is lost, the
AC fail signal is activated.
3.1.5
Outputs
The PSS module also includes the following:
•
Front panel AC power on indicator voltage (J5).
•
Circulation fan power (J6) or (J4) * (J4 for use with older style fan
connectors).
•
On / Off switch (state of switch high-low signal sent through J2 pin 6
to the MC board).
•
Circulation fan current sense information (hard-wired at J8) connects
to (J12) on the PC board.
