Can someone explain to me how a 24 volt battery can power components that advertise requiring 28 volts to operate?
The aircraft I fly has a 28 VDC generator that powers both battery and generator buses under normal ops, but in the event of generator failure, the bus tie opens and isolates the battery bus. The 24 VDC battery then gives you 30 minutes of power to the battery bus.
But today I found that the solenoid dump valve, which needs 28 volts to remain closed and keep the aircraft pressurized, is on the battery bus and (supposedly) still operates normally when the 28 volt generator fails and the 24 volt battery takes over. What am I missing?
That 24v is sufficient for the valve - it has a wider working range than just 28v.