Tuesday, July 10, 2012

Cessna 152 Electrical System

Electrical Power Supply System.                                                                                                         Battery and External Power Supply System.                                                                                    Alternator Power System                                                                                                                   Aircraft Lighting System                                                                                                                          Pitot Heater.                                                                                                                                             Stall Warning,                                                                                                                                      
ELECTRICAL POWER SUPPLY- SYSTEM.- Electrical energy for the aircraft is supplied by a 28-volt, direct-current.single wire. negative ground electrical system.                                                                                                                    A 24-volt battery supplies power for starting and furnishes a reserve source of power in the event of alternator failure.                                                                                                                        An engine-driven alternator is the normal source of power during flight and maintains  battery charge controlled by a voltage regulator/alternator control unit.                                                      An external power source receptacle is offered as optional equipment to supplement the battery alternator system for starting and ground operation.
BUS BAR: Electrical power for electrical equipment and electronic installations is
supplied through the split bus bar. The bus bar is interconnected by a jumper wire and attached to the circuit breaker on the lower, center of the instrument panel.
MASTER SWITCH: The master switch controls the operation of the battery and alternator
systems. The switch is an interlocking split rocker with the battery mode on the right hand
side and the alternator mode on the left hand side. This arrangement allows the battery to be
on the line without the alternator, however. operation of the alternator without the battery on
the line is not possible. The switch is labeled "BAT" and "ALT" below the switch and is
located on the left-hand side of the Panel
AMMETER: The ammeter is connected between the battery contactor and the bus bar.  The meter indicates the amount of current flowing either to or from the battery.                            
BATTERY: The battery is 24 volts and 17 ampere-hour capacity or 12.75 ampere-hour capacity or a 15.5 ampere-hour capacity . The battery is mounted on the forward side of the firewall and is equipped with non-spill caps.
BATTERY BOX: The battery box is constructed of metal and painted inside and out with
acid-proof paint. The box is attached to the right hand side of the firewall. 
BATTERY CONTACTOR: The battery contactor is a plunger type and is actuated by turning on the master switch. The contactor is bolted to the left hand side of the firewalL A silicon diode is installed to eliminate spiking of transistorized radio equipment when the contactor is closed. Nylon covers are installed on the terminals to prevent accidental short circuits
BATTERY CONTACTOR CLOSING CIRCUIT. The battery contactor closing circuit consists of a 5-amp fuse. a resistor and a diode installed across the battery contactor. This serves to shunt a small charge around the battery contactor when the battery is too dead to energize the contactor by itself
ALTERNATOR: The alternator is three phase. delta connected with integal silicon diode rectifiers. The alternator is rated at 28 volts at 60 amperes continuous output. The resulting do output is applied to the aircraft bus and sensed by the voltage regulator. The regualtor controls the excitation applied to the alternator field thus controlling the output of the alternator
VOLTAGE REGULATOR ;The voltage regulator is a solid state regulator. The regulator is a remove and replace item and not repairable in the field. 
ALTERNATOR CONTROL UNIT ;The alternator control unit is a solid state voltage regulator with an overvoltage sensor and low-voltage sensor incorporated in the unit. The control unit is not adjustable and is a remove-and-replace item. 
The landing and taxi light is mounted in the lower half of the engine cowl. This position facilitates the use of one lamp or both a landing and taxi light. A light cover provides weather protection for the lamp. The landing and taxi light is controlled by a rocker type switch located on the instrument panel A circuit breaker is used to protect the landing and taxi light circuit
MAP LIGHT: White map lighting and red non-glare instrument lighting are provided by an adjustable light mounted on the upper forward part of the left door post. The switch is a three position type with red, white and off positions. 
An electrical heater unit may be installed in the pitot tube. The heater offsets the possibility of ice formation on the pitot tube. The heater is integrally mounted in the pitot tube and is operated by a rocker switch on the instrument panel


Unknown said...

Where is the shunt located for the ammeter?

Greg Broburg said...

There is no shunt in the factory ammeter. Rather the Ammeter functions by a magnetic path behind the indicator needle which has a permanent magnet mounted to the shaft of the indicator needle.

Anonymous said...

What is the DC system voltage