1). What is an electrical system as shown below?
- Transformer
- MV Switchgear
- LV MCC / Switchgear
- Synchronize Panel
- Generator
- NGR (Neutral Grounding Resistance)
- Capacitor Bank
- Electrical Motor system
- Distribution Board
- UPS system
- Grounding system
- Lightning Protection
- Lighting System
a). A transformer refers to a power appliance that can change AC from one voltage level to another level. This can be either designed to ‘step up’ of ‘step down’ voltage and operates on the magnetic induction principle. A transformer is a completely rigid, fixed-electronic device that is devoid of any moving part thus ensuring in application conditions a long and Billy- hassle-free operation.
b). MV Switchgear (or) Medium Voltage Switchgear is switchgear that is classified in the range of 3 KV up to 36 KV switchgear network. These switchgears are of many types. They may include
- Metal enclosed indoor type,
- Metal enclosed outdoor type,
- Outdoor type without metal enclosure, etc.
The interruption medium of this switchgear may be
- Oil Circuit Breaker,
- SF-6 Circuit Breaker and
- Vacuum Circuit Breaker.
The basic characteristic which defines the requirements to the MV power network is to interrupt current in the faulty condition, including the case when any type of CB is used in the MV switchgear system.
c). LV Switchgear or Low Voltage Switchgear electrical switchgear is classified as those installed with ratings up to 1 kV.
LV Switchgear refer to all the accessories such as
- Low Voltage Circuit Breakers,
- Switches,
- Off load electrical isolators,
- HRC fuses,
- Earth Leakage Circuit Breaker,
- Miniature Circuit Breakers (MCB) and
- Molded Case Circuit Breakers (MCCB) etc.
that protects the LV system.
d). Synchronization panels are mainly designed and utilized with respect to specified power system characteristics. These panels work manually and have an in-built automatic synchronizing feature for 2 or more generators or Breakers. They are commonly employed in the applications of synchronizing the generators and providing multiplexing solutions.
e). Generator is an apparatus by which motive power which is a form of electrical energy is transformed into electrical energy for utilization in other electrical circuit.
Mechanical energy sources are
- Steam turbines,
- Gas turbines,
- Water turbines,
- C engines,
- Wind turbines and
- Hand cranks etc.
f). NGRs are applied to reduce the fault current for the protection of equipment and persons in industrial power systems. In solid grounding, the system is directly grounded and it is only by the value of the soil resistance that the fault current is restricted.
The fault current is normally very high this current can damage transformers, generators, motors wiring and other equipments in the system. The NGRs are connected to the neutral and ground in such a way that there is increased net resistance in the case of an earth fault and thus reduce the amount of current that flows in the circuit to a safe amount.
g). Capacitor Bank is a number of capacitors which have similar ratings connected either in series or parallel to store electrical energy. The resulting bank is then used in order to react a power factor lead of lag or phase shift in an alternating current power supply.
h). Electrical machines that convert electricity into mechanical energy are called electric motors. Almost all electric motors work using the combination of the magnetic field associated with the motor and electric current passing through a wire winding to produce force in the form of torque applied on the motor’s shaft.
DC supply can be
- Batteries,
- Motor vehicles,
- Rectifiers
while AC supply is the
- Power grid,
- Inverters or
- Electrical generators.
An electric generator is mechanically very similar to an electric motor but works in a reverse direction that is converting mechanical energy to electrical energy.
i). A distribution board is an element of electrical power supply that is used to divide an electrical power feed into branches as well as incorporates fuses or circuit breakers for each branch in a single compartment.
j). UPS or Uninterruptible Power Supply is an equipment that offers batteries or ‘power conditioning’ when electrical power is off or exists in an undesirable voltage. Small UPS systems give power for a few minutes; this is just enough to bring down the computer gracefully, while larger UPS have enough battery for several hours.
k). Grounding system or the intentional connection of a phase or neutral conductor to earth for the purpose of controlling the voltage to earth, or ground , within predictable limits. It also calls for the provision of a current flow that will enable detection of the undesirable connection between system conductors and the ground.
l) Their main objective of a lightning protection system is to divert that high voltage electrical energy to a less damaging path to the ground and not allow it to flow through the buildings electrical wiring, water piping, structure or low voltage cabling path where it could cause havoc inside the building.
m). Lighting systems make for efficient use of energy and hence the costs since they assist in providing the light only at the times and place that it is required. History has it that most illumination systems all encompass time schedules, occupancy control, and photocell control. Some systems also have demand response and will the lights in my house dim or turn off to benefit from special offers from the electricity providers. More often such systems are integrated into a broader system known as building automation systems.
2). What should electricians know about safety?
Most important safety concerns for electrician are:
- Touching live parts and getting an electric shock and burns.
- Defects that would likely lead to fires, and
- Fire or explosion in which electrical energy could be a possible cause in a potentially explosive or flammable environment.
3). What are the distinctions between the two categories of maintenance known as preventive and corrective maintenance?
| Preventive Maintenance | Corrective Maintenance |
| Preventive is maintenance is done where there is no problem. | Corrective maintenance is done where there was a problem |
| Preventive maintenance is carried out, often and systematically. | Corrective maintenance is carried out more often at random. |
| Preventive maintenance will maximize the corrective activities. | Corrective maintenance will reduce the need for the preventive. |
4). What are the tools used for electrical work?
Tools used for electrical works are:
- Pliers
- Screwdrivers and nut drivers
- Wire strippers
- Fishing tools
- Measuring devices (Multimeter, Voltmeter etc.)
- Labeling machines
- Power drills and drivers – hammer/drills
- Power saws.
5). What do you consider to be the most important skills for Electricians?
Critical skills for electricians are:
- Electrical installation and safety is knowledge
- Good vision
- Team work
- Basic math
- Problem solve skill
- Physical fitness
- Flexibility
6). What is the primary difference between a breaker and a fuse?
- A fuse and a circuit breaker of them both control an overloaded circuit through interrupting the continuity of current.
- A fuse is a piece of metal that is designed to melt when there is a short circuit in the supply of current while a circuit breaker is a device that shuts down a circuit when it detects dangerous flow of current.
- Fuses cause a much faster interruption of the current flow, however, it has the disadvantage of needing replacement once a piece of metal has melted, while circuit breakers can be reset multiple of times.
7). What is the Electrical Calibration?
Electrical calibration can be described as the act of checking or altering the performance of any measuring or testing instruments that deals with electrical parameters.
Typically, this field of study is referred to as low frequency and DC electrical metrology.
Some main parameters of electrical circuit include
- Voltage,
- Current,
- Resistance,
- Inductance,
- Capacitance,
- Time as well as frequency.
Other parameters such as electrical power and phase are also in this segment of metrology.
Simple percentage relations of like quantities are used to compare one like quantity to another unknown like quantity.
8). What is the difference between Installation and Reparation?
| Installation | Reparation |
| An electrical installment can therefore be described as a compilation of electrical devices connected as a circuit from a given power source to serve an intended function. | Reparation is an act that repairs the components which involve adjustments, melting or replacing some of the part of the object to work as it is supposed to work. |
9). What is the Motor Starting?
Motor starting or motor starter is an electric motor that turns an inner combustion engine and keeps the turning until the engine itself has enough power to turn then like in cars.
10). What is a kWh meter?
Kwh meter is the electric meter that records the amount of electrical energy in units of kwh that is taken in the house.
A kWh meter has a counter section where the regulator records the units of kilowatt hour abbreviated as kWh.
Energy consumption is derived by verifying the difference of the counter’s reading from the mentioned period.
