Q's & A's
What is the difference between generator and alternator?
An alternator is a charging system for cars that produces electricity. Generators are used in the production of large-scale electricity. Both alternators and generators convert mechanical energy into electrical energy. The main difference between them is in regard to what spins and what is fixed. In an alternator, electricity is produced when a magnetic field spins inside the stator (windings of wire). In a generator, on the other hand, the armature or windings of wire spin inside a fixed magnetic field to generate electricity.
What is analog-to-digital conversion of signals?
Analog-to-digital conversion is an electronic process in which a continuously variable (analog) signal is changed, without altering its essential content, into a multi-level (digital) signal.
What is your understanding of Australian engineering standard 61508?
IEC 61508. IEC 61508 is an international standard published by the International Electrotechnical Commission consisting of methods on how to apply, design, deploy and maintain automatic protection systems called safety-related systems.
Why AC systems are preferred over DC systems?
a. It is easy to maintain and change the voltage of AC electricity for transmission and distribution. b. Plant cost for AC transmission (circuit breakers, transformers etc) is much lower than the equivalent DC transmission c. From power stations, AC is produced so it is better to use AC then DC instead of converting it. d. When a large fault occurs in a network, it is easier to interrupt in an AC system, as the sine wave current will naturally tend to zero at some point making the current easier to interrupt.
What are the various kind of cables used for transmission?
Cables, which are used for transmitting power, can be categorized in three forms: • Low-tension cables, which can transmit voltage up to 1000 volts. • High-tension cables can transmit voltage up to 23000 volts. • Super tension cables can transmit voltage 66 kV to 132 kV.
Can you explain the difference between direct and alternating current?
In direct current (DC), the electric charge (current) only flows in one direction. Electric charge in alternating current (AC), on the other hand, changes direction periodically. The voltage in AC circuits also periodically reverses because the current changes direction.
Explain Norton's Theorem in a single sentence.
Norton on the other hand reduces his circuit down to a single resistance in parallel with a constant current source. Norton's Theorem states that "Any linear circuit containing several energy sources and resistances can be replaced by a single Constant Current generator in parallel with a Single Resistor".
How can you relate power engineering with electrical engineering?
Power engineering is a sub division of electrical engineering. It deals with generation, transmission and distribution of energy in electrical form. Design of all power equipment also comes under power engineering. Power engineers may work on the design and maintenance of the power grid i.e. called on grid systems and they might work on off grid systems that are not connected to the system.
What is the difference between a single pole and a double pole circuit breaker?
Single-pole breakers: Provide 120 volts, 15-20 amps and have one hot wire and one neutral wire. Double-pole breakers: Provide 240 volts, 20-60 amps and have two hot wires that share one neutral wire.
What is slip in an induction motor?
Slip can be defined as the difference between the flux speed (Ns) and the rotor speed (N). Speed of the rotor of an induction motor is always less than its synchronous speed. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol 'S'.
Why star delta starter is preferred with induction motor?
Star delta starter is preferred with induction motor due to following reasons: • Starting current is reduced 3-4 times of the direct current due to which voltage drops and hence it causes less losses. • Star delta starter circuit comes in circuit first during starting of motor, which reduces voltage 3 times, that is why current also reduces up to 3 times and hence less motor burning is caused. • In addition, starting torque is increased and it prevents the damage of motor winding.
Explain the application of storage batteries.
Storage batteries are used for various purposes, some of the applications are mentioned below: • For the operation of protective devices and for emergency lighting at generating stations and substations • For starting, ignition and lighting of automobiles, aircrafts etc. • For lighting on steam and diesel railways trains. • As a supply power source in telephone exchange, laboratories and broad casting stations.• For emergency lighting at hospitals, banks, rural areas where electricity supplies are not possible.
A capacitor has a label on it saying, "100 WVDC". What does this label mean and what is the consequence of exceeding this rating?
The capacitor's working voltage is 100 volts DC. Failure of the dielectric material will result from exceeding this voltage rating. In electrolytic capacitors especially, the failure can be violent!
Why back emf(electromotive force) used for a dc motor? highlight its significance.
The induced emf developed when the rotating conductors of the armature between the poles of magnet, in a DC motor, cut the magnetic flux, opposes the current flowing through the conductor, when the armature rotates, is called back emf. Its value depends upon the speed of rotation of the armature conductors. In starting, the value of back emf is zero.
What are some of the most common causes of transformer humming?
The main cause of transformer noise is the Magnetostriction Effect. ... The alternation current that flows through an electrical transformer's coils has a magnetic effect on its iron core. It causes the core to expand and contract, resulting in a humming sound.
