Electrical System Flashcards
NATOPS Chap 2
Electrical System
The Primary source of AC power is… Secondary Source?
Two AC generators which are driven by the transmission.
The APU Generator
NATOPS Chap 2
Electrical System
How is DC Power provided to system?
Two DC converters turn 115 VAC power into 28 VDC power.
NATOPS Chap 2
Electrical System
What is the battery, and what is it used for?
The battery is a 24v Nickel Cadmium installed primarily to start the APU and power the Battery Util Bus.
NATOPS Chap 2
Electrical System
Describe the 3 Gens?
Oil cooled 30/45 K-VA, 115 VAC, 3-phase, 400Hz for Gen 1/2
Air cooled 35 K-VA, 115 VAC, 3-phase, 400Hz for APU Gen
NATOPS Chap 2
Electrical System
What does a GCU do?
It connects each gen to the ac electrical bus, regulates gen output, and protects system components against overvoltage, undervoltage, feeder fault, and underfrequency
NATOPS Chap 2
Electrical System
At what Nr will the GCUs disconnect the generators while on the ground and in the air?
On the ground, 94% Nr
In the air, 80% Nr
The GCUs will reconnect Gens to the AC buses at 97% Nr
NATOPS Chap 2
Electrical System
What is external power monitored for?
Over/under voltage, phase rotation, under/overfrequency
NATOPS Chap 2
Electrical System
What are the Three Little Pigs?
1) Backup Hyd pump (#1 AC Pri)
2) Mission Pwr (AC Secondary bus) [TR deice is also on
this bus]
3) MR Deice (AC Monitor Bus)
NATOPS Chap 2
Electrical System
When do the GEN cautions appear? (3 times)
- Respective gen is not supplying power to the Buses
- Respective Gen is selected off
- A failure of the Gen, GCU, Contactor control relay, or wiring fault has occured
NATOPS Chap 2
Electrical System
When does the APU GEN ON advisory appear
When the generator is supplying electrical power to a primary bus
NATOPS Chap 2
Electrical System
When does the APU GEN caution appear (2x)
- Failure of the APU-driven gen, GCU, contactor contol
relay, or wiring fault - APU gen selected on, APU started, but has not
reached op limits
NATOPS Chap 2
Electrical System
What is the primary purpose of of the battery?
It provides 24VDC to start the APU and to power the dc essential bus and the battery bus.
NATOPS Chap 2
Electrical System
What is the normal battery life?
With an 80% charge, the battery will operate 11min during the day, and 9min at night
NATOPS Chap 2
Electrical System
What is the purpose of the batt analyzer/conditioner?
It monitors the battery for:
- ) Fault condition
- ) Battery charge
- ) Internal temperature
- ) Cell conditions
- ) and provides a battery-charging capability.
NATOPS Chap 2
Electrical System
What does the conditioner do if it detects a fault?
It will automatically disconnect the dc loads from the battery, or the battery from the charging circuit as necessary