2A672 Volume 1 Ure Questions

An element is the simplest form of matter because it consists of only one type of atom. Atoms are the basic building blocks of matter, and elements are made up of identical atoms. They cannot be broken down into simpler substances by chemical means. In contrast, mixtures are composed of two or more different substances, compounds are made up of two or more different elements chemically combined, and electrons are subatomic particles that are part of atoms.

Valence electrons are the electrons located in the outermost energy level of an atom. These electrons have the highest energy because they are farthest away from the positively charged nucleus and experience less attraction. As a result, valence electrons are more easily involved in chemical reactions and can be transferred or shared with other atoms to form chemical bonds.

Electromagnetic induction is the correct answer because it refers to the process by which a voltage is induced in a conductor when it is exposed to a changing magnetic field. When the magnetic field expands or collapses, it creates a flux linkage with the conductor, resulting in the generation of an electromotive force (voltage) according to Faraday's law of electromagnetic induction. This phenomenon is the basis for the functioning of devices such as generators and transformers.

When the size of the plates of a capacitor is increased, the distance between the plates decreases. This leads to an increase in the electric field between the plates, resulting in an increase in the capacitance. The capacitance of a capacitor is directly proportional to the size of the plates, so when the size is increased, the capacitance also increases.

The torsion shaft is specifically designed to break if the engine locks up. This component is responsible for transmitting torque from the engine to other parts, such as the compressor shaft. If the engine locks up and the torsion shaft is unable to handle the excessive force, it will break, preventing further damage to the engine.

The scavenge pump is responsible for drawing excess oil from the gear case in the -60A lubrication system on a gas turbine engine. This pump helps to remove any excess oil that may accumulate in the gear case, ensuring that the engine operates efficiently and preventing any potential damage caused by an excessive amount of oil.

The factors that affect the resistance of a material are the area of the material, the temperature at which it is being used, and the type of material itself. The area of the material affects resistance because a larger area allows for more current to flow, resulting in lower resistance. Temperature affects resistance because as temperature increases, the atoms in the material vibrate more, causing more collisions with electrons and increasing resistance. The type of material also affects resistance because different materials have different atomic structures and electron configurations, which can impact the ease of electron flow and therefore resistance.

An open circuit refers to a break or discontinuity in the circuit, which prevents the flow of current. In this case, there is no current flow. On the other hand, a short circuit occurs when there is an unintended connection between two points in the circuit, resulting in excessive current flow. Therefore, the correct answer states that there is no current flow in an open circuit, while there is excessive current flow in a shorted component.

A silicon-controlled rectifier (SCR) is primarily used as an electronic switch. It is a semiconductor device that can control the flow of electric current. By applying a small voltage to the gate terminal, the SCR can be turned on and allow current to flow through it. Once triggered, it remains conducting even if the gate voltage is removed. This characteristic makes it suitable for applications where a high voltage or high current needs to be controlled, such as in power control circuits, motor control, and lighting dimmers.

The major difference between an NPN transistor and a PNP transistor is the direction of current flow. In an NPN transistor, the current flows from the collector to the emitter, while in a PNP transistor, the current flows from the emitter to the collector. This difference in current flow direction is due to the arrangement of the layers of the transistor and the type of doping used.

The probable cause of the excessively high exhaust gas temperature in a -60A is the pneumatic thermostat. The pneumatic thermostat is responsible for regulating the temperature in the engine by controlling the flow of air and fuel. If the pneumatic thermostat is malfunctioning or not functioning properly, it may result in an imbalance in the air-fuel mixture, leading to higher exhaust gas temperatures.

A step-down transformer contains more turns in the primary winding than in the secondary winding. This type of transformer is used to decrease the voltage level from the primary side to the secondary side. By having more turns in the primary winding, the transformer can step down the voltage and increase the current in the secondary winding. This is commonly used in power distribution systems to deliver lower voltage levels to households and businesses.

When the B809A generator set AC card senses an AC supply fault, the AC contactor opens and the generator output stops. This means that the connection between the AC card and the AC supply is interrupted, causing the AC contactor to open and prevent the generator from supplying power. This action is taken to protect the generator and prevent any further damage or malfunction due to the AC supply fault.

The basic principle of operation for transformers is mutual induction. Mutual induction refers to the phenomenon where a changing current in one coil induces a voltage in a nearby coil. In the case of transformers, the primary coil is connected to an alternating current source, which creates a changing magnetic field. This changing magnetic field induces a voltage in the secondary coil, allowing for the transfer of electrical energy from one circuit to another. Mutual induction is essential for the functioning of transformers and is the basis for their ability to step up or step down voltage levels.

The area where P-type material is joined to N-type material in a semiconductor is known as the depletion region. This region is formed due to the diffusion of charge carriers from one region to another, resulting in the formation of a region depleted of majority charge carriers. The depletion region acts as a barrier to the flow of current until a sufficient voltage is applied to overcome this barrier.

When a small potential is applied to the gate of a silicon-controlled rectifier (SCR), the middle junction of the SCR becomes forward biased. This means that the P-type material in the middle junction becomes more positive with respect to the N-type material. This forward biasing allows current to flow through the SCR and turns it on. As a result, the SCR conducts current from anode to cathode.

The correct answer is (T1) and rectifier (CR26). The voltage regulator supplies exciter field voltage through a transformer (T1) and a rectifier (CR26). The transformer steps up or steps down the voltage to the required level, while the rectifier converts the AC voltage into DC voltage. Together, they provide the exciter field voltage necessary for the voltage regulator to regulate the output voltage of the generator. The other options mentioned (T2, B1, T3, B2, B3) are not involved in supplying the exciter field voltage.

To convert milliamps to standard amperage, you need to divide the value in milliamps by 1000. In this case, 500 milliamps divided by 1000 equals 0.5 amps. Therefore, the correct answer is 0.5 amps.

When the diameter of the core in an inductor is increased, the magnetic lines of force passing through the coil also increase. This is because a larger core allows for more magnetic flux to flow through it, resulting in a stronger magnetic field. As a result, the induction of the coil increases, meaning that the coil will generate a larger electromotive force (EMF) or voltage.

The best point to check voltage to the -86D exciter field is at J8, terminal D-F.

The correct answer is low lube pressure. The low lube pressure safety circuit in the B809A generator set engine incorporates a seven-second time delay before activation. This delay allows the engine to properly build up oil pressure before the safety circuit is activated, providing enough time for the engine to start and operate normally. This safety feature helps prevent damage to the engine due to insufficient lubrication.

Atoms having more than four electrons, but less than eight are known as insulators because insulators are materials that do not easily conduct electricity. These atoms have a partially filled valence shell, which makes it difficult for them to gain or lose electrons and form stable bonds with other atoms. As a result, they do not readily conduct electricity and are poor conductors of heat.

The electrostatic fields around a positive ion move outward. This is because positive ions have a deficiency of electrons, resulting in an excess of positive charge. As a result, the electrostatic fields emanating from the positive ion repel other positive charges and attract negative charges. This repulsion causes the fields to extend outward from the ion, creating a region of influence where other charges are affected. Therefore, the correct answer is outward.

The three leads in a unijunction transistor (UJT) are called emitter, base 1, and base 2.

The emitter in a unijunction transistor always points toward the base 1 lead. This is because the base 1 lead is the primary terminal that controls the operation of the transistor. The emitter is responsible for emitting the majority charge carriers (electrons or holes) into the base region, and it needs to be oriented towards the base 1 lead for proper functioning. The collector is the terminal that collects the charge carriers, and the gate is not relevant to a unijunction transistor.

The voltage regulator VR1 controls the strength of the -86D exciter field L2. This means that VR1 determines the amount of voltage supplied to the exciter field, which in turn affects the strength of the field. By adjusting the voltage, the voltage regulator can control the strength of the exciter field, allowing for precise control over the generator's output.

Total current is equal throughout series part of circuit. So since I1 (in series part) = 9 amps, IT = 9 amps. Parallel branches always add up to equal current flow in series part. So, I2 (5 amps) + I3 (?) = 9 amps. I3 has to equal 4 amps.

The injector pump is the component on the B809A generator set fuel system that distributes and delivers an accurate amount of fuel to the engine cylinders. It is responsible for pressurizing the fuel and delivering it to the injectors at the correct timing and quantity. The injectors then spray the fuel into the combustion chambers for efficient combustion. The injector pump plays a crucial role in ensuring that the engine receives the right amount of fuel for optimal performance.

During the first cycle of alternating current (AC) in a circuit using a bridge rectifier, two diodes are forward biased. The bridge rectifier consists of four diodes arranged in a bridge configuration. During the positive half cycle of AC, two diodes (D1 and D3) are forward biased and conduct current, while the other two diodes (D2 and D4) are reverse biased and do not conduct. This allows the current to flow in one direction, converting AC to pulsating DC. Therefore, the correct answer is 2.

Switch S15 to the L-N position. This action will change the voltmeter measurement from 200 volts AC to line-to-neutral voltage, which is the correct measurement for a three-phase system. Adjusting VR1 or R61 would not address the issue of incorrect voltage measurement.

40/2^2 = 40/4 = 10 ohms

Find RT of parallel resistors: RT = 8x8/8+8 = 64/16 = 4
New R2 is RT of parallel resistors. Now use RT = R1 (7) + R2 (4) = 11 ohms

The valence band of an intrinsic semiconductor is the highest energy band that is fully occupied by electrons at absolute zero temperature. In an intrinsic semiconductor, each atom contributes one valence electron, which is shared with neighboring atoms to form covalent bonds. Since each atom has four valence electrons, the valence band of an intrinsic semiconductor has four electrons.

The line drop switch must be placed in the "ON" position when adjustments are made to a voltage regulator. This is because the switch is responsible for controlling the flow of electricity in the circuit. By turning it on, the circuit is closed and allows the regulated voltage to be adjusted and controlled.

The probable cause of the undervoltage light coming on when placing S13 in the build up position while operating a -86D at governed speed is the memory time delay relay.

A capacitive circuit is one in which the current leads the applied voltage by 90 degrees. This means that the current reaches its peak value before the voltage does. Capacitors store and release electrical energy, and in a capacitive circuit, the flow of current is determined by the rate at which the voltage changes. As the voltage increases, the capacitor charges and allows current to flow, causing the current to lead the voltage. Therefore, the statement "current leads applied voltage by 90 degrees" best describes a capacitive circuit.

A zener diode is connected in parallel to the load in order to regulate voltage. By connecting it in parallel, the zener diode acts as a voltage regulator by maintaining a constant voltage across the load. When the voltage exceeds the zener voltage, the diode starts conducting and effectively regulates the voltage by diverting excess current. This ensures that the voltage across the load remains constant, even if the input voltage fluctuates.

If a schematic diagram doesn't list a reference for the zener diode, it is likely being used as a spike protector. A zener diode is a type of diode that is designed to operate in the reverse breakdown region, allowing it to regulate voltage and protect against voltage spikes. In this case, since there is no reference given for the zener diode, it is most likely being used to protect against voltage spikes rather than as a voltage regulator or a normal diode.

The probable cause of the trouble is the governor trim control. The governor trim control is responsible for adjusting the fuel flow to the engine in order to maintain a specific speed. If the trim control is not functioning properly, it can result in the unit operating at a lower speed, such as 97 percent, instead of the desired speed.

The power factor meter is used during performing resistive and reactive load tests simultaneously. This is because resistive loads only consume true power, while reactive loads consume both true power and reactive power. By using the power factor meter, we can measure the power factor, which is the ratio of true power to apparent power. This allows us to determine the efficiency of the load and make adjustments if necessary.

If the arrow in a bipolar transistor is pointing away from the base, it indicates that the transistor is an NPN type. In an NPN transistor, the majority charge carriers are negative electrons, and the arrow points in the direction of the conventional current flow.

A unijunction transistor (UJT) typically has one junction. This junction is formed between the emitter and the base regions of the transistor. The UJT operates by controlling the current flow between the emitter and the base, making it a useful device for applications such as oscillators and timing circuits.

The probable cause of the trouble is that the K23 contacts are open. This means that there is no electrical connection being made, which is preventing the voltage from building up.

Apparent power is a measure of the total power in an AC circuit, taking into account both the active power (measured in kilowatts, KW) and the reactive power. It is represented in kilo-volt-amperes (KVA) because it is the product of the voltage (measured in volts) and the current (measured in amperes). This unit is used to quantify the total power that a circuit or device can handle, considering both the real and reactive components of power.

In P-type material, the majority carriers are holes, which are positively charged. Minority carriers, on the other hand, are the minority of charge carriers present in the material. In P-type material, the minority carriers are electrons, which are negatively charged. These electrons are introduced into the material through the process of doping, where impurities are added to the material to create an excess of electrons.

The zener diode is connected in parallel to the load in order to protect it. When the voltage across the load exceeds the zener diode's breakdown voltage, the diode starts conducting and limits the voltage to its breakdown voltage. This prevents any excessive voltage from reaching the load and protects it from damage. Connecting the zener diode in parallel to the load ensures that it only conducts when necessary, providing effective protection.

The contacts on the annunciator card of the B809A generator set control the AC power input to the voltage regulator when there is a fault in the generator. This means that if there is a fault detected in the generator, the contacts on the annunciator card will be responsible for controlling the AC power input to the voltage regulator.

The DC card on the B809A generator set senses the condition of overtemperature. This means that the card is designed to detect and monitor the temperature of the generator set, and if it exceeds a certain threshold, it will trigger a response or alarm to prevent any damage or malfunction caused by excessive heat.

The correct answer is S5, run/idle toggle switch. When operating a B809A generator, closing the run/idle toggle switch (S5) provides potential to the exciter field. This switch controls the generator's operating mode, allowing it to switch between running and idle modes. By closing this switch, the necessary power is supplied to the exciter field, ensuring proper functioning of the generator.

The oil pressure relief valve controls the output of the main oil pump by bypassing excess oil back to the main pump inlet. This means that when the oil pressure exceeds a certain threshold, the relief valve opens and allows the excess oil to flow back into the main pump. By doing so, it prevents the oil pressure from becoming too high and ensures that the system operates within the desired pressure range.