Electric Flashcards
Location of the APU battery?
Aft equipment bay
Max Engine generator load?
40kVA
Max APU Generator load?
40 kVA
Max transformer rectifier unit (TRU) load ?
120 amps
Location of the MAIN battery
Nose compartment
Max permissible time for ground operations with battery power only?
5 minutes
What is the reason for the 5 minute limitation for ground operations while on battery power only?
To prevent ED1 and ED2 from overheating (fans are AC powered)
How many TRUs are installed in the CRJ 900?
4
Where are the TRUs located?
Nose compartment
The MAIN battery is rated to?
17 amps / 24 volts
The APU battery is rated to
43 amps / 24 volts
How many generators are installed?
4
2 Engine Generators
1 APU Generator (Auxiliary Power Unit)
1 ADG (Air Driven Generator)
What is the function of the 4 TRUs?
To convert 115 V AC to 28 V DC
Which buses are powered when the Battery Master switch is selected on?
Main battery direct bus
APU battery direct bus
DC battery bus
If the main buses are powered, are the essential buses automatically powered?
Yes
Is there an ON / OFF switch for the TRUs?
No, they are automatically powered when the AC busses are powered
What controls the DC tie contactors?
The DC Power Centers (DCPC) automatically control the DC tie operation
When will the Air Driven Generator (ADG) automatically deploy?
With complete loss of A/C power
With the ADG deployed, what are the basic items that are powered?
AC ESS bus
Hydraulic pump 3B
Flaps / Slats
STAB trim Ch 2
What is the ADG max load?
15 kVA
How are the TRUs cooled?
Individual fans
What is the overload protection for IDG?
45 KVA for 5 minutes
60 KVA for 5 seconds
What is a GCU?
Generator control unit-each generator has one. The GCU provides protection and voltage regulation for its engine generator. The GCUs in conjunction with the AC power center provide bus priority and protection during normal and non-normal operations. The generator output would be tripped off and removed for:
- Over/under voltage
- over/under frequency
- generator and bus over current
- generator phase sequence
- AC power center (ACPC)
What is ACPC?
AC power center - distributes AC power to the aircraft sub-systems. ACPC contains system power contractors, current transformer seem lies and circuit breakers for the purpose of switching AC power to the appropriate electrical bus.
Provides secondary power distribution to hydraulic pumps, slats and flaps and pitch trim circuits via circuit breakers and relays / contractors that are controlled by their specific system control units.
What does APU generator do?
Supplies AC electrical power to the aircraft buses during ground operations with the engines off. APU generator can be used to power the buses in flight should an engine fail.
What is an auxiliary GPU?
Controls, monitors and provides protection and voltage regulation for the APU generator.
What provides bus priority logic during normal and non-normal operations?
ACPC and GCUs. In t he case of the APU, it’s the ACPC and AUXILIARY GCU.
What is an EPM?
External power monitor. It controls and monitors the external power source. The AC power receptacle is located on the forward right side if the aircraft below the External Service panel. The status if the external AC power source is displayed on the AC Electrical page.
Priority for external power
External power is the lowest priority and can only be selected if there are no other aircraft power generation sources online. If the priority is correct and the external,power supply is within acceptable limits, the IN USE switch light can be selected. AVAIL means the power is acceptable - it has correct voltage, frequency and phase
External Service Panel AC switchlight
An External AC switchlight is available on the external service panel. It’s function is identical to the AC AVAIL/IN USE on the overhead panel except one thing- when you depress it, it allows external power to be applied to the aircraft in the SERVICE configuration - which supplies AC power to the AC service bus ONLY. If the AC AVAIL/IN USE switchlight is subsequently pressed, it will have priority over external selection from the panel and will allow external power to the entire aircraft electrical power system.
What are the 4 AC buses?
AC bus 1 - located behind pilot - feeds AC ESS bus
AC bus 2- located behind co-pilot- feeds AC SERV bus
AC ESS (essential) bus
AC SERV (service) bus
Bus 1 and 2 can receive power from any of the 3 aircraft generators
What does AC Service bus do and where does it get it’s power?
AC service bus provides power to service outlets for passenger cabin and lavatory cleaning. AC service bus may also get power from the external AC system when in the SERVICE configuration. Pushing EXT AC PUSH light on external service panel, allows external AC power energize the AC Service bus ONLY- without turning in other buses.
What is powered when using ADG?
ADG is deployed automatically when power is lost in AC bus 1 AND bus 2. This allows power to be distributed to:
Slats/flaps
Stab trim channel 2
Hydraulic 3B pump
AC Essential bus.
The AC Essential bus will then power ESS TRU 1, which in turn provides DC power to the DC Essential and DC battery buses (DC ESS tie closes).
What is ADG stall?
Between 155 and 160 KIAS, the essential DC bus is load shed causing the loss of ESS TRU 1 and 2, XFLOW pump, the left probe heaters, ice detection and window heat. To prevent this “ADG stall” the aircraft must be configured no later than 140 KIAS
He distribution centers for DC power?
2-left and right. The TRU system carries the majority of the DC electrical loads and the battery system provides emergency power in flight and allows APU to be started on the ground.
What is DCPC?
2 -DC power centers and 4 circuit breaker panels. Two panels in the flight compartment, one in aft equipment bay, and forward unpressurized nose compartment. DC distribution controlled from EPCP and DC tie contractors located within the DCPCs.
How many DC buses?
Nine DC bus 1 DC bus 2 DC ESS (essential bus) DC Service bus DC UTIL DC BATT (battery) bus DC EMERG bus Main BATT Direct bus APU BATT Direct bus
