Electrical

Question 1

Main Generators

Answer 1

2x oil cooled 30/45 kVA, 115 Vac, 3 phase 400 Hz driven by transmission accessory modules

Question 2

APU Generator

Answer 2

35 kVA, 115 Vac, 3 phase, 400 Hz driven by APU

Question 3

Generator Control Unit (GCU)

Answer 3

Connects each respective generator to the ac electrical bus system, regulates generator output, and protects system components and circuitry against overvoltage, undervoltage, feeder fault, and underfrequency

• NOTE* Should the main rotor system droop below 94% Nr, on the ground, the GCU, via an input from the WOW switch, removes the main generator electrical input from the entire ac power distribution system
• NOTE* In flight, underfrequency protection is disabled and generators will remain online until the Nr decreases to approximately 80%. A minimum of 97% Nr is required for the GCU to reconnect the No 1/2 generators

Question 4

External Power

Answer 4

Monitored for phase rotation, overvoltage, undervoltage, underfrequency and overfrequency

System includes 4 amp c/b that places a 2 amp draw on the power cable

NOTE To connect external power to the aircraft, the EXT POWER switch must be toggled to RESET, then ON

Automatically disconnected from aircraft when either a main or APU generator is brought online (don’t drop your codes on the boat!)

Question 5

AC Electrical Buses / Distribution

Answer 5

No 1/2 AC PRI
AC ESSENTIAL
AC SECONDARY
AC MONITOR

No 1 gen - No 1 AC PRI, ESNTL, SEC

No 2 gen - No 2 AC PRI, MON

Question 6

3 Electrical Pigs

Answer 6

1. Backup hydraulic pump will always be powered (No 1 AC PRI)
2. Mission avionics is next priority (AC SEC) [tail rotor deice is also on this bus]
3. Main rotor deice has lowest priority of the major current-drawing components (AC MON)

(2-45 has ac power distro chart)

Question 7

DC Power

Answer 7

Two converters supply 28 Vdc; powered by No 1/2 AC PRI buses

Question 8

Battery

Answer 8

24 Vdc nickel-cadmium (NICAD) battery–primary source for starting APU and secondary source for DC ESNTL and BATT buses; with 80% charge, normal life is 11 min for day and 9 min for night

Analyzer/conditioner monitors for fault conditions, battery charge, internal temp, cell conditions and provides battery charging capability

Receives ac power from No 2 AC PRI and dc charge from No 2 DC PRI

Low charge at 40%

NOTE With no other source of dc power and battery below 30% charge, battery power may be insufficient to activate the fire extinguisher CAD

Question 9

DC Electrical Buses / Distribution

Answer 9

No 1/2 DC PRI
DC ESNTL
BATT BUS
BATT UTIL

No 1 converter - No 1 DC PRI, DC ESNTL, BATT
No 2 converter - No 2 DC PRI
Battery - BATT UTIL

Question 10

DC Pick Up

Answer 10

If one converter fails, other picks up the load

If both fail, battery provides source of emergency power to the BATT UTIL, BATT (if battery switch is ON) and DC ESNTL (if battery above 35% charge)

Question 11

Dual Converter Failure

Answer 11

Both flight and mission displays will be lost