PTM Ch. 2 Electrical Power Systems

Question 1

What volt DC system do we have?

Answer 1

28 V DC

Question 2

What AC voltage do we use?

Answer 2

26 and 115 V AV

Question 3

What kind of batteries do we have?

Answer 3

Lead acid

Question 4

What is AC power used for?

Answer 4

Flight instruments and avionics

Question 5

What essential bus do the inverters run off of?

Answer 5

No 1: left

No 2: right

Question 6

What are the transferable items from the left essential bus to the right essential bus?

Answer 6

1. Fuel crossflow valve
2. Surface deice boots
3. Landing gear control
4. Landing gear position indicator
5. Cabin pressure dump
6. Left engine intake heat
7. Right engine intake heat
8. Windshield heat
9. Turn and slip
10. Pilot instruments

Question 7

Should you test the voltage of the batteries with the battery switch on?

Answer 7

No. It’ll show the highest voltage of any power source connected.

Question 8

What should you do prior to turning the batteries on?

Answer 8

Reset the battery switch.

Question 9

What should you do before turning the generators on?

Answer 9

Reset the generator switch.

Question 10

What two conditions must be satisfied for the battery fault detection circuit to be operative?

Answer 10

1. At least one battery switch must be on
2. Either both generator switches must be on

Or

Left generator switch must be on and GPU plug must be in the external power receptacle

Question 11

How much DC voltage does the generator put out?

Answer 11

28 V DC

Question 12

What is the permissible generator continuous load except during generator assist starts and during battery recharging after engine start?

Answer 12

300 Amps

Not to exceed 2 minutes

Question 13

What are the six features of the GCU? Only very good rabbits gain riches.

Answer 13

1. Over voltage
2. Voltage Regulation
3. Generator Paralleling
4. Reverse Current Protection
5. Ground Fault Protection
6. Relay Control

Question 14

What does placing the generator reset do?

Answer 14

Reset the protection circuit if the fault no longer exists

Question 15

What is the max load during cross starts?

Answer 15

100 Amps

Question 16

What can happen if you shutdown an engine without turning off the respective generator?

Answer 16

Blow the 325 Amp limiter circuit breaker

Question 17

Where is the GCU located?

Answer 17

In the respective wheel well

Question 18

How to perform current limiter check

Answer 18

1. Turn off both batteries and one generator.
2. Press the test button on the annunciator panel
3. If panel test is normal all 3 DC busses are powered and the current limiters are intact.

Question 19

When should current limiter check be done?

Answer 19

After cross generator start

Question 20

What amp limitation do we have on GPU’s?

Answer 20

1000 amps

Question 21

Where is the battery bus located?

Answer 21

Junction box, behind captain’s seat

Question 22

How many inverters can be used at any time?

Answer 22

One

Question 23

What is the acronym to remember all 10 items that are transferable from the left essential bus to the right essential bus?

Answer 23

I- Instruments (pilot’s) and turn-and-slip

F- fuel crossflow valve

P- pressurization dump

I- ice equipment (surface deice, left and right engine intake heat, left windshield heat)

G- gear (landing gear control and landing gear indication)

Question 24

Where are the inverters located?

Answer 24

In the back on the rack.

Question 25

What does both AC Annunciators mean?

Answer 25

Loss of inverter. Switch to the other inverter

Question 26

What does 1 AC Annunciator light mean?

Answer 26

The 115 AC bus tie circuit breaker popped.

Question 27

The 115-VAC and 26-VAC bus tie circuit breakers located where?

Answer 27

On the nonessential bus even though they’re not powered by the nonessential bus.

Question 28

The generators are limited to what amperage below 1000’ for what reason.

Answer 28

200 amps because of cooling