Electrical

Question 1

When is the ground service bus powered?

Answer 1

When the GPU is powered, connected to the aircraft but GPU knob not selected and the batteries are off.

Question 2

How many generators and what is there respective voltage capacity for the EMB145?

Answer 2

The EMB145 has 5 generators capable of producing 28v DC and 400 Amps.

Question 3

Can the GPU be used to recharge the aircraft main batteries?

Answer 3

No; When the GPU is connected and supplying power to the aircraft the battery contactors (BC) 1 and 2 open automatically.

Question 4

What items are powered from the 115 VAC bus?

Answer 4

TCAS, EGPWS and Windshear.

Question 5

Which electrical bus supply power to the ISIS on the EMB145XR?

Answer 5

The backup battery hot bus.

Question 6

Under what conditions are the shed buses powered while on the ground?

Answer 6

With GPU powering the aircraft (shed buses knob on AUTO or OVRD), with one generator online and the shed buses knob on “OVRD” position, or with 3 or more generators online.

Question 7

What criteria must be established in order to have shed bus power in flight?

Answer 7

At least 3+ generators must be online for the shed buses to be power in flight.

Question 8

Is DME available when in essential power?

Answer 8

No; but VOR and LOC type approaches can be flown if DME is not required.

Question 9

Define the EICAS message master warning “ELEC ESS XFR FAIL”.

Answer 9

The electrical system has failed to transfer into essential power. Batteries are powering the entire electrical system.

Question 10

What does the “GPU AVAIL” inscription on the GPU button indicates?

Answer 10

GPU is physically connected to the aircraft.

Question 11

What action should be taken if the battery voltage is less than 24v after powering the aircraft?

Answer 11

If battery voltage is between 24v and 19v; Start the APU with the GPU, if available. If the voltage is less than 19v, maintenance action is required.

Question 12

What should be the GPU power prior to accepting it into the system?

Answer 12

Between 26v and 29v.

Question 13

What is the purpose of de-selecting the backup battery on the first flight of the day for the EMB145XR?

Answer 13

To ensure that the sole power source powering the backup hot bus is the backup battery.

Question 14

What appropriate action should be taken if a CB is “popped” r to aircraft power-up?

Answer 14

Do not reset, contact MX and to discover the cause.

Question 15

When may a CB be reset in flight?

Answer 15

A CB may not be reset or cycled unless doing so is consistent with the CFM/OM/QRH procedures or unless in the judgement of the PIC such reset is necessary for the safe completion of the flight.

Question 16

What is the CB reset/cycling procedure?

Answer 16

A three minute cool down period is required. If the CB trip again, DO NOT ATTEMPT ANOTHER RESET. After completion of the flight, a maintenance discrepancy entry is required. Do not reset any fuel system CB’s.

Question 17

What happens when the “ESS PWR” button is pressed?

Answer 17

It forces the electrical system into essential power regardless of the electrical distribution logic (EDL) command.

Question 18

Define essential power.

Answer 18

The batteries are the only source of power for the essential buses.

Question 19

The backup battery power’s what electrical components?

Answer 19

The GCU’s, EDL and ISIS.

Question 20

How many APU starts are available on essential power?

Answer 20

3 APU starts.

Question 21

What are the batteries function during APU start?

Answer 21

BC 1 opens to isolate battery #1, as battery #1 powers essential and electrically sensitive items like the GCU’s, EDL and APU FADAC. BC 2 stay closed to power the central bus(The central bus powers the APU starter generator).