Electrical System - Piper SEMINOLE PA-44-180 Information Manual

PA-44-180, SEMINOLE

7.17 ELECTRICAL SYSTEM

The electrical system is a negative-ground, dual-fed, split-bus system
capable of supplying sufficient current for complete night IFR equipment.
ALTERNATORS
The primary electrical power is supplied by two belt-driven 14 volt, 70
ampere alternators (Figure 7-19), one mounted on each engine. The alternator
provides full electrical power output even at low engine rpm. This provides
improved radio and electrical equipment operation and increases battery life
by reducing battery load.
VOLTAGE REGULATORS
Each alternator is protected by an alternator control unit which
incorporates a voltage regulator and an overvoltage relay. The regulators
maintain effective load sharing while regulating electrical system bus voltage
to 14-volts. An overvoltage relay in each alternator circuit prevents damage to
electrical and avionics equipment by taking an alternator off the line if its
output exceeds 17-volts. If this should occur, the ALTernator light on the
annunciator panel will illuminate.
BATTERY
A 35 ampere-hour, 12-volt battery provides current for starting, for use of
electrical equipment when the engines are not running, and for a source of
stored electrical power to back up the alternator output. The battery, which is
located in the nose section is normally kept charged by the alternators. If it
becomes necessary to charge the battery, it should be removed from the
airplane.
ISSUED: JULY 12, 1995
REVISED: NOVEMBER 1, 2001
SECTION 7
DESCR/OPERATION
REPORT: VB-1616
7-19