Electrical System

Why it is require to do "flashing of the exciter field" for DC generator and when it is required to do flashing?

• Residual magnetism in the generator exciter field allows the generator to rotate in the armature coil.

  It is sometimes lost due to excessive heat.

• Residual magnetism in the generator exciter field allows the generator to build up voltage during start-up. It is sometimes lost due to shelf time or improper operation

• Residual magnetism in the generator exciter field allows the generator to pick up the output from commutator. It is sometimes lost due to high current.

• Residual magnetism in the generator exciter field allows to build up the output voltage. It is sometimes lost due to the imbalance rotation speed.

What will happen when DC external power unit is being used on aircraft, suddenly the shorter positive pin is broken?

• A big arcing will be created at the pins

• The circuit breaker pop-out / trip

• DC is still being supplied to the DC Bus Bar

• No more DC is available at DC Bus Bar

What if a surface light or wing illumination light failed to function on aircraft?

• The pilot could not detect the formation of ice on the flap of the wings.

• The pilot could not check navigation position during a night flight.

• The pilot could not check flap position during a night flight.

• The pilot could not detect the formation of ice on the leading edges of the wings.

Which is NOT TRUE about the DC generator?

• Reducing the output ripple will cause the increase of segment of the commutators

• DC Generator require a carbon brush for take out the output from

  commutator segment.

• Generator with more commutator segments will have more generated voltage output

• The generated output voltage can be increased by increasing the armature coil length

What is the internal resistance of a battery?

• The resistance present inside the battery while connected to a load

• The resistance present inside the battery while it is charging.

• The resistance measured across the two terminals.

• The resistance that will increase the output current of the battery.

Which of the following is NOT TRUE about AC brushless generator?

• Three phase armature winding is used in the main generator stage only

• Third stage involves in the rotation armature

• Second stage involves in voltage regulation

• PMG is used in the pilot exciter

Which of the following should

NOT change the specific gravity of an aircraft battery?

• When aircraft lead acid battery has reach fully charged condition.

• When aircraft lead acid battery has reach fully discharged condition.

• When aircraft lead acid battery is in charging process.

• When the aircraft Ni-Cad battery is in charging process.

What is the purpose of fluorescent coating in the fluorescent tube?

• To make the fluorescent tube to change color and increase the brightness

• To cause the ultra violet radiation to emit a longer wavelength radiation in the visible spectrum.

• To make the fluorescent tube reduces its temperature.

• To cause the ultra violet radiation to emit a light photon.

How could the intensity /

brightness of incandescent lamp be controlled?

• Use variable transformer for dimming control by varying voltage to the lamp.

• Use a zener diode either in parallel or in series.

• Use a rheostat type of dimming control to vary current to the lamp

• Adjust the front opening of the lamp.

What will be the effect to the system if pin E and F of the AC external power connection has NO continuity?

• The bus power control unit (BPCU) will open the external power contactor (EPC).

• The external power contactor (EPC) will be shorted and burn the EPC.

• The external power contactor (EPC) will be energized regardless of this pins.

• The bus power control unit (BPCU) will close the external power contactor

  (EPC)