Chapter 3: Inverters
Function
Converts D.C. power supply to A.C. power during emergency
Operating critical equipment
Range on aircraft
Output: 26V to 115V, 400 Hz (a.c.)
Input: 24V or 26V (d.c.)
Types of inverters
Static
Rotary
Uses solid state technology
Looks like a motor or generator
26V or 115V 400Hz a.c.
Heavy
Noisy
Used in smaller or older aircrafts
D.C. (24V - 28V) to A.C. (115V 400Hz)
Produced in 2 stages:
Stage 1 - Step up the voltage level to that required
Stage 2 - Frequency generated to that required
Difference between older and newer static inverters
Older
Newer
Uses standard electric and electronic components like transformers, capacitors, transistors and crystal diodes.
Oscillator circuit is able to produce 400Hz
Bulky
Converts power in 2 stages
First stage converts low inverter input voltage D.C to 145V or 290 D.C.
Second stage converts the high voltage into a 115V single phase 400Hz A.C.
Provides A.C power to:
Attitude and directional gyro,
rate gyro,
autosyn indicators and transmitters, magnesyn indicators and transmitters,
radar
Static over Rotary
Uses solid stage technology
No rotary parts
Extremely accurate and reliable
Lighter than a rotary inverter
High efficiency
Low maintenance, longer life
No warming up period required
Capable of starting under load
Extremely quiet operation
Very little heat generated
Fast response to load changes
Principle of operation
Square waves --> Fourier series