Cessna 172 Electrical System

Question 1

Describe the Master Switch (C172)

Answer 1

The master switch is a split rocker type switch labeled MASTER, the right half of the switch , labeled BAT, controls all electrical power to the airplane. The left half, labeled ALT, controls the alternator

Question 2

Describe the Avionics Power Switch (C172)

Answer 2

A toggle-type circuit breaker-switch labeled AVIONICS POWER. The switch also functions as a circuit breaker

Question 3

Describe the Ammeter (C172)

Answer 3

The Ammeter indicated the flow of current, in amperes, from the alternator to the battery or from the battery to the airplane electrical system

Question 4

Describe the over-voltage sensor and warning light (C172)

Answer 4

The airplane is equipped with an automatic over-voltage protection system consisting of an over-voltage sensor behind the instrument panel and a red warning light labeled HIGH VOLTAGE.

Question 5

If the over voltage light were illuminated what would this tell the pilot? (C172)

Answer 5

That the over voltage sensor automatically removed the alternator field current and shut down the alternator

Question 6

What is the electrical system protected by in case of a short? (C172)

Answer 6

Circuit breakers and fuses

Question 7

Describe the electrical system in a Cessna 172N

Answer 7

Electrical energy is supplied by a 28 volt, direct current system powered by an engine driven, 60 amp alternator and a 24 volt, 14 amp hour battery located on the left side of the firewall. Power is supplied to most general electrical and all avionics circuits through the primary and avionics bus bar, which are interconnected by an avionics power switch.