Instruments such as voltage meters, either digital or analogue dial type are often installed in aircraft to measure and display the battery voltage to pilots. This can be useful to ensure the electrical system is charging the battery during flight and that the battery is voltage remains within specifications for the aircraft.
The standard voltage regulator/rectifier used on 912 engines provides the charging current to the battery and regulates the voltage to the required set point.
The input to the Rect/Reg is the AC voltage from the generator coil. The rect/reg does not produce a perfectly clean DC output waveform. It has a 22,000uF external capacitor to help smooth the output, but equipment must be designed to work on the DC bus by rejecting any stray pulses superimposed to this DC bus for consumer equipment (VHF, iPADs, GPS, etc)
I am investigating an aircraft with pusles on the 12V DC supply. The onboard voltage meter fluctuates +/-0.3V rapidly. There seems to be excessive noise on the 12V.
Question
1. What waveforms or specifications for the correct operating conditions exist to help resolve and varify the correct operation of the Rect/Reg output?
2. Are there any published waveforms which show the acceptable performance of the electrical parts? i.e. expected noise pulse levels, Frequency of noise versus engine RPM, etc
3. In an installation with no consumer loads, can a rect/reg be partially damaged by over heating due to not enough electrical load causing the internals to disipate excess power as heat?
The standard voltage regulator/rectifier used on 912 engines provides the charging current to the battery and regulates the voltage to the required set point.
The input to the Rect/Reg is the AC voltage from the generator coil. The rect/reg does not produce a perfectly clean DC output waveform. It has a 22,000uF external capacitor to help smooth the output, but equipment must be designed to work on the DC bus by rejecting any stray pulses superimposed to this DC bus for consumer equipment (VHF, iPADs, GPS, etc)
I am investigating an aircraft with pusles on the 12V DC supply. The onboard voltage meter fluctuates +/-0.3V rapidly. There seems to be excessive noise on the 12V.
Question
1. What waveforms or specifications for the correct operating conditions exist to help resolve and varify the correct operation of the Rect/Reg output?
2. Are there any published waveforms which show the acceptable performance of the electrical parts? i.e. expected noise pulse levels, Frequency of noise versus engine RPM, etc
3. In an installation with no consumer loads, can a rect/reg be partially damaged by over heating due to not enough electrical load causing the internals to disipate excess power as heat?
