A thermal circuit breaker ?
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The auxiliary power unit APU has its own AC generator that ?
A magnetic circuit breaker is ?
The advantages of alternating current on board an aircraft are 1 simple connection2 high starting torque3 flexibility in use4 lighter weight of equipment5 easy to convert into direct current6 easy maintenance of machinesthe combination of correct statements 3, 4, 5, 6,, 2, 3, 4, 5, 6,, 2, 3, 5, 6,, 4, 6. Alternating current (ac) extremely versatile has following advantages over direct current. ac can be simply efficiently changed from one voltage to another using a transformer. ac generators are simpler in construction, lighter, the equivalent power output of a dc machine. ac can be easily efficiently changed into dc using a rectifier. 
On board present aircraft batteries used are mainly cadmium nickel their advantages are 1 low risk of thermal runaway2 high internal resistance hence higher power3 good charging and discharging capability at high rating4 wider permissible temperature range5 good storage capability6 sturdiness owing to its metal casing7 electrolyte density remains unchanged during charging the combination of correct statement 3, 4, 5, 6, 3, 4, 6, 7, 2, 3, 4, 5, 6,, 2, 5, 6, 7. The terminal voltage remains substantially constant at about 1.2 volts throughout most of discharge. due to its low internal resistance it also capable of supply high current during its discharge cycle low current during recharging without violent fluctuations of terminal voltage. nicad batteries have a low thermal capacity, heat generated in certain conditions faster than it can dissipate, so causing rapid increase in temperature. this has effect of lowering effective internal resistance thus allowing an ever increasing charging current, which, unless checked, leads to total destruction of battery. 
A static inverter powered Direct current on input, alternating current output, alternating current on input, direct current on output, alternating current on input, alternating current on output, direct current on input, direct current on output. an inverter a unit used to convert dc into ac. dc to ac inverter. ac to dc rectifier. 
The voltage regulator of a dc generator connected in Series with shunt field coil, series with armature, parallel with shunt field coil, parallel with armature. On a dc generator, voltage regulation achieved changing voltage in voltage coil, which changes carbon pile pressure, which changes current in shunt field. the voltage regulator connected in series with shunt field coil. Question Electrics 25 Answer 8
During start of an engine fitted with a brushless ac generator with no commutator rings generator activated A set of permanent magnets, main field winding, stabiliser winding jointly with voltage regulator, auxiliary winding. Question Electrics 25 Answer 9
The type of windings commonly used in dc starter motors are Series wound, shunt wound, series shunt wound, compound wound. Dc motors are classified as to ways in wich their field excitation circuits are arranged (series wound, shunt wound, compound wound). the series wound motors have their field armature windings in series with each other, so same current flows through both, adding them together. these motors have a high starting torque especially as, in initial stages, there little back emf, so all current used in them. they are commonly used as starter motors. Question Electrics 25 Answer 10
The power output of a generator controlled Varying field strength, varying speed of engine, reverse current relay circuit breaker, varying length of wire in armature windings. The only practical method of controlling output voltage of a generator to control strength of magnetic field controlling current flow in a coil wound around magnetic pole pieces (field coil or field winding) control of current flow achieved a voltage regulator. the voltage regulator senses output voltage of generator or alternator adjusts field current to maintain correct output voltage irrespective of generator speed or electrical load. Question Electrics 25 Answer 11
A relay A magnetically operated switch, another name a solenoid valve, a unit that used to convert electrical energy to heat energy, a device that used to increase electrical power. Question Electrics 25 Answer 12
The voltage of a fully charged lead acid battery cell 2.2 volts,.4 volts,.8 volts,.2 volts. Question Electrics 25 Answer 13
The capacity of a battery given in Ampere hours, amperes/volts, watts, ohms. Question Electrics 25 Answer 14
A relay An electromagnetically operated switch, an electrical security switch, a switch specially designed ac circuits, an electrical energy conversion unit. Question Electrics 25 Answer 15
The most widely used electrical frequency in aircraft 4 hz, 2 hz, 5hz, 6hz. Question Electrics 25 Answer 16
If electrical load of an ac generator providing a constant output voltage increases voltage regulator will Increase intensity of excitation current, change direction of excitation current, maintain intensity of excitation current constant, decrease intensity of excitation current. The output regulated varying current to field windings. the voltage regulator senses alternator output adjusts field current when a voltage rises above a set value (typically 115.5 v). the current cut off around 2000 times a second. the voltage regulator there to stop battery being overcharged or system being overloaded. Question Electrics 25 Answer 17
The so called 'hot buse or 'direct buse are Directly connected to battery, kept in operating conditions an electrical resistance in case of energy failure, automatically connected to battery if generators have failed, providing an alternative current. Question Electrics 25 Answer 18
The reason using inverters in an electrical system To change dc into ac, to change dc voltage, to change ac into dc, to avoid a short circuit. Question Electrics 25 Answer 19
The function of a constant speed drive csd to ensure That generator produces a constant frequency, that starter motor maintains a constant rpm irrespective of engine acceleration/deceleration, that csd output remains at a constant rpm irrespective of generator rpm, an equal ac voltage output from all generators. Question Electrics 25 Answer 20
A bus bar A distribution point electrical power, a device which may only be used in dc circuits, stator of a moving coil instrument, a device permitting operation of two or more switches together. Question Electrics 25 Answer 21
A csd of an ac generator may be disconnected in flight the primary reason s disconnection are Low oil pressure and/or high oil temperature of generator drive, slight variation about normal operating frequency, excessive variation of voltage kvar, illumination of csd disconnect warning light. Question Electrics 25 Answer 22
A csd unit which has been disconnected in flight May be reset on ground only, after engine shut down, automatically resets at engine shut down, automatically resets in flight providing engine rpm below a given value, may be reset in flight using reset mechanism. Question Electrics 25 Answer 23
Because of input/output relationship of an or gate it often referred to as 'any' or 'al gate, 'all or nothing' gate, 'state indicator' gate, 'inhibite or 'negate gate. Question Electrics 25 Answer 24
Connecting two 12 volt 40 ampere hour capacity batteries in series will result in a total voltage and capacity respectively of 24 volts, 4ampere hours,2 volts, 8ampere hours,2 volts, 4ampere hours, 24 volts, 8ampere hours. Question Electrics 25 Answer 25
When a conductor cuts flux of a magnetic field An electromotive force (emf) induced in conductor, there will be no effect on conductor, current will flow in accordance with flemings left hand rule, field will collapse. Question Electrics 25 Answer 26
In order that dc generators will achieve equal load sharing when operating in parallel it necessary to ensure that Their voltages are almost equal, equal loads are connected to each generator busbar before paralleling, adequate voltage differences exist, synchronising bus bar disconnected from busbar system. When two dc generators are operating in parallel, control of load sharing achieved an equalising circuit which, in conjunction with voltage regulators, varies field excitation current of generators. Question Electrics 25 Answer 27
The purpose of a voltage regulator to control output voltage of Generator at varying loads speeds, batteries at varying loads, generators at varying speeds the batteries at varying loads, tru. For dc generators, voltage regulation achieved changing voltage in voltage coil which changes carbon pile pressure which changes current in shunt field. this then the reactive load (wasted power) that adjusts energising current. the same principle applies in ac generators (alternators) but they use solid state circuitry. Question Electrics 25 Answer 28
A current limiter fuse in a dc generation system used to Allow a short term overload before rupturing, limit current in field circuit, allow no overload before rupturing, limit current in armature. A fuse a deliberately weak part of a circuit that designed to fail if a problems occurs. current limiters are like fuses, but with a much higher melting point so that a higher overload current can be carried (they allow a short term overload). they will limit current to a predetermined value are used heavy duty circuits. Question Electrics 25 Answer 29
A 3 phase ac generator has 3 separate stator windings spaced at 2 °, 6 °, 45°, 9 °. Question Electrics 25 Answer 30
A csd unit normally provided with means of monitoring during flight Oil temperature pressure, oil temperature synchronous speed, output voltage oil pressure, oil temperature quantity only. Question Electrics 25 Answer 31
The phase relationship between two unparalleled ac generators Is unimportant, must be synchronous, must be in opposition, must be 9 ° out of synchronisation. Question Electrics 25 Answer 32
Assuming a csd fault indicated csd should be disconnected Provided engine running, at flight idle engine rpm, on ground only, when ac generator voltage outside limits. The function of a constant speed drive (csd) to ensure that ac generator produces a constant frequency. in case of csd fault, you must disconnect it (if engine running, if not, since ac generator not rotating you don't need to disconnect it). a csd unit which has been disconnected may be reset on ground only, after engine shut down. Question Electrics 25 Answer 33
Ac generators operated in parallel must have same Voltage phase, voltage amperage, amperage kvar, frequency amperage. Two ac generators operated in parallel must be not only at same speed (voltage) but also same phase to be paralleled. Question Electrics 25 Answer 34
The measured output power components of a constant frequency ac system are Kva kvar, volts amperes, volts kilowatts, amperes kilowatts. Question Electrics 25 Answer 35
'frequency wil in relation to a ac generation system means generator Output frequency varies with engine speed, output frequency too high, output frequency too low, voltage regulator out of adjustment. Question Electrics 25 Answer 36
When ac voltage across a capacitor kept constant and frequency increased current through capacitor will Increase, remain same, be zero, decrease. Capacitive reactance when frequency tends to zero, current magnitude almost equal to zero. at contrary, when fequency high, this the magnitude of voltage which tends to zero. we are talking about capacitive reactance xc expresses in ohm. Question Electrics 25 Answer 37
In an aeroplane fitted with a constant frequency ac power supply dc power obtained from a Transformer rectifier unit (tru), static inverter, 3 phase current transformer unit, rotary converter. Question Electrics 25 Answer 38
On an aeroplane using ac as primary power supply batteries are charged in flight from A transformer rectifier unit, a static inverter, a dc transformer rectifier, ac bus via current limiters. Question Electrics 25 Answer 39
Immediately after starting engine s with no other electrical services switched on an ammeter showing a high charge rate to battery Would be normal is only cause concern if high charge rate persists, indicates a generator failure, thus requiring engine to be shut down immediately, indicates a faulty reverse current relay, indicates a battery failure since there should be no immediate charge. If engine was started electrically using battery, there would have been a significant drain on battery. the ammeter shows a charge after start up to replenish energy just drained from battery. Question Electrics 25 Answer 40
Circuit breakers protecting circuits may be Used in ac dc circuits, used only in ac circuits, used only in dc circuits, reset at any time.
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