All systems in the aircraft are protected by push to reset circuit breakers or switch breakers.
Should an overload occur, the resulting heat rise will cause the respective circuit breaker to pop out providing electrical circuit protection.
Should a circuit or switch breaker open circuit, it may be reset after allowing the circuit to cool down (approximately 3 minutes).
Any circuit or switch breaker can only be reset once for safety reasons. If the circuit continues to fail it must be attended to by qualified maintenance personnel.
Positioning the battery switches to ON connects both batteries in parallel to the battery bus.
The battery bus is linked to each main bus through 250 ampere current limiters (fuses) located in the nose compartment.
The battery bus and current limiters provide a tie between the left and right main buses so that if one generator should fail electrical power is maintained to the entire electrical system.
If both generators fail power is still available to the entire system by the battery bus.
Should both generators fail it is important to reduce the electrical load to essential items only as soon as possible.
Both batteries fully charged have only a combined 44 ampere hour capacity so electrical power won’t last that long.
When using battery power to start the aircraft engines it is recommended that the left engine be started first as an extra set of starting cables is provided to the left starter-generator to reduce power loses during the start cycle.
Once the left engine has been started, the left generator can be brought online to aid the start cycle for the right engine.
Before starting the right engine, ensure that the charging current of the left generator is below 200 amperes (75 amperes if the ambient temp. is below freezing).
This technique of using the left generator and batteries is called a 'cross start' and is the reason only one set of start leads is provided on the aircraft.
The generator control units regulate the starter generator modes of operation.
Below 60% engine RPM the starter-generator operates as a starter.
Above 60% engine RPM the starter-generator operates as a generator.
Inverters and A.C. power
An inverter (sometimes a backup inverter is fitted too) located in the avionics bay of the nose compartment is used to convert 28VDC to 26VAC at 400 hertz to supply the 1000 series Integrated Flight Control System (IFCS) and Radio Magnetic indicator.
Other items using AC power such as the Radar will have a separate inverter.