Electrical Power (24) Flashcards
What does EPGDS stand for and what does it do?
Electrical Power Generation and Distribution System
- Generates and distribute DC Power
- Store electrical energy
- External power distribution
How many systems are in the EPGDS?
2
What provides electrical power?
By two Brushless Starter Generators (BSGs) and their relative Brushless Control Units (BCUs).
How many batteries are part of the EPGDS?
2
- Main
- Auxillary
How many busses are there in the EPGDS?
8
- MAIN 1 & 2
- ESS 1 & 2
- NON-ESS 1 & 2
- EMER 1 & 2
Are EPGSD 1 and 2 connected in normal flight?
NO
The bus tie is open
How are the busses controlled?
By the two AMMCs (except the EMER busses)
What makes up EPGDS 1?
- BSG 1
- BCU 1
- MAIN 1
- MAIN 3
- NON-ESS 1
- NON-ESS 3
- EMER 1
- ESS 1
- MAIN BATT
What makes up EPGDS 2?
- BSG 2
- BCU 2
- MAIN 2
- MAIN 4
- NON-ESS 2
- NON-ESS 4
- EMER 2
- ESS 2
- AUX BATT
Where are the BSGs installed?
On the engine reduction gearbox
How are the BSGs cooled?
Air cooled
Where are the BCUs installed?
Rear avionics bay
How are the BSGs controlled?
By the BCUs
Electrical inputs tell is to work as either a starter or generator
What protections do the BCUs provide during start?
- Locked rotor or wrong direction
- Overcurrent
- Over-temp
During generating mode what protections are implemented by the BCUs?
- Starter to generator switchover interlock
- Over and under voltage protection
- Over current protection (include short circuit)
- Under and Over frequency protection
Describe the Main battery
24Vdc, 33Ah NiCd
At what temperature will an over-temperature alam generate in either battery?
71°C
Describe the Auxiliary battery
24Vdc, 13Ah Ni-Cd
What does the Auxillary battery do?
- Powers the EMER & ESS loads during:
- Engine starting
- During double gen failure
- On the ground (engines not running and no EXT pwr) - Provides Overtemp warning
- Can be recharged by EXT pwr
What rating is the EXT pwr?
28 Vdc
What does EXT Pwr provide?
- Power to ALL busses
- Powers the starter during engine starting
What does PDU stand for and what do they do?
Power Distribution Unit
- Connects electrical power sources (BSGs/BATTs) to the left and right Busses.
- Checks and connects EXT pwr to the distribution Busses.
- Controls the BUS TIE contactor.
What does CBP stand for and which Busbars are on it?
Circuit Breaker Panel
- Only EMER 1 and EMER 2
What does REPU stand for?
Remote Electrical Power Unit
(Virtual Circuit breakers and bus bars)
What do the REPUs do?
Physically control the power distribution to the helicopter equipments.
- SOLID STATE CIRCUIT BREAKERS
How many REPUs are fitted to the aircraft?
3
- 2x in nose avionics bay
- 1x in the rear avionics bay
How are the solid state circuit breakers controlled?
Via the ECDU
What does the MCOS switch do?
Master Cut-OFF switch
- isolates the electrics in an emergency
Can you override the BUS TIE and NON ESS busbars
YES
Via the EDCU Electrical Control Page
How are the solid state circuit breakers controlled by the pilot?
Via the EDCU
What are the EPGDS Interfaces?
Engine starting
WOW
Integration & Displays
SSEPMS
What does PSGS stand for?
Power Start Generation Subsystem
2 BSGs
2 BCUs
What does PDCS stand for?
Power Distribution and Control Subsystem
2x PDUs
1x CBP
1x Control Panel
1x 28Vdc power recepticle
What does CBP mean?
Circuit Breaker Panel
(We have 2; EMERG BUS 1 & 2)
What is on REPU 1?
MAIN 1
NON ESS 1
ESS 1
What is on REPU 2?
MAIN BUS 2
Non ESSS 2
ESS 2
What is on REPU 3?
MAIN BUS 3
Non Ess 3
MAIN BUS 4
Non Ess 4
Where is the External Power receptacle located?
On the aft of the right sponson
What is the BCUs role in starting?
24Vdc is inverted to the required six-phase 24Vac to turn the BSG
What is the BCUs role during power generation?
BSG Outputs 24Vac to the BCU which converts to 28Vdc at 300A to the PDU
Where is the main battery located?
Rear avionics bay
Does the Aux Batt assist with the start?
NO - It maintains ESS & EMER Bus Bars
Where are the PDUs located?
Rear avionics bay
What does SSEPMS Stand for?
Solid State Electrical Power Management System
(Contains REPUs)
What is in PDU1?
Gen BUS 1 (BCU1)
Batt Bus 1 (Main Batt)
What is in PDU2?
Gen Bus 2 (BCU2 & Ext Pwr)
Batt Bus 2 (Aux)
What does the Master Cut-off Switch do?
Isolates electric in an emergency
(except if aircraft is powered by EXT PWR)
What does FAILED mean on the EDCU CB Page?
The breaker itself has FAILED
It cannot be reset
What does TRIPPED mean in the EDCU CB Page?
An overcurrent or under voltage has been detected and the virtual circuit breaker has been tripped.
It can be reset.
Can you get a [1(2) BCU HOT] in flight?
No
What are the affects of [MAIN/AUX BATT OFF]
Not being charged
Not connected as a backup
What is powered when power is first applied (power up)
Batt Bus 1 & 2
ESS Bus 1 & 2
EMER BUS 1 & 2
(Main and NESS powered off to save battery)
What maintains BATT, ESS and EMERG Busses whilst carrying out a Battery start?
AUX BATT
At what Ng does the BCU terminate the starter motor?
52%
At what Ng does the BCU turn the BSG into generation mode?
64% Ng
What is cross-start assist?
The online GEN will assist the start of the second engine
Assisted by the main battery
What’s happens to the EXT PWR once the generator is online
It is automatically disconnected from the EPGDS (EPC Open)
at 52% Ng
What happens to Non-ESS Busbars during a single generator failure?
The Non-ESS Busses are automatically shed
Can the shedding of the NON-ESS busses be overridden?
YES - via EDCU
What conditions require and aborted engine start
- No light up in 10
- HOT START
- ITT shows X
- Hangs below 60%
- START fails to disengage by 54%
