Alternator, battery and bus bar
Power source: alternator plus battery (PHAK ch.7).
- Alternator over generator: useful output at low RPM (taxi, idle) (PHAK ch.7).
- Generator needs high RPM to charge (TP 1102 l.7038).
Components:
| Component | Function | Cite |
|---|---|---|
| Master switch | Connects the battery | TP 1102 |
| Alternator switch | Separate; controls the alternator | TP 1102 |
| Starter | Cranks engine from the battery | PHAK ch.7 |
| Voltage regulator | Controls rate of charge to the battery | PHAK ch.7 |
Ammeter (reads current to/from battery), a center-zero gauge:
- Needle on + side = alternator charging battery. Normal.
- Full-scale plus deflection = voltage regulator malfunction (PHAK ch.7).
Loadmeter (fitted to some aircraft instead of ammeter) (PHAK ch.7):
- Zero-based, not center-zero.
- Reads percentage of system generating capacity in use.
- All electrical items off: reads only battery charging demand.
Bus bar: common point distributing voltage from battery/alternator to all circuits (PHAK ch.7).
Lighting: master switch feeds position, anticollision, landing, taxi and interior cabin lights (PHAK ch.7).
Trap: loadmeter with all items off reads battery charging demand, not zero.
References
- TP 1102 (Flight Training Manual), Emergency Procedures: Electrical Fire
- FAA-H-8083-25 PHAK ch.7 (Electrical System)
- TC AIM AIR
- POH/AFM