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Topic includes
- Electric power transmission
- Overhead transmission
- Underground transmission
- Bulk power transmission
- Some IE rules
- Conditional and requirement Domestic installation
- Conditional and requirement Domestic installation
Transmission
Electric power transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is part of electricity delivery, known as the "power grid" in North America, or just "the grid". In the United Kingdom, India, Tanzania, Myanmar, Malaysia and New Zealand, the network is known as the National Grid.
500 kV Three-phase electric power Transmission Lines at Grand Coulee Dam; four circuits are shown; two additional circuits are obscured by trees on the right; the entire 7079 MW generation capacity of the dam is accommodated by these six circuits.
Most transmission lines are high-voltage three-phase alternating current (AC), although single phase AC is sometimes used in railway electrification systems. High-voltage direct-current (HVDC) technology is used for greater efficiency over very long distances (typically hundreds of miles). HVDC technology is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links are used to stabilize large power distribution networks where sudden new loads, or blackouts, in one part of a network can result in synchronization problems and cascading failures.
Electricity is transmitted at high voltages (66 kV or above) to reduce the energy loss which occurs in long-distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher installation cost and greater operational limitations, but reduced maintenance costs. Underground transmission is sometimes used in urban areas or environmentally sensitive locations.
High-voltage overhead conductors are not covered by insulation. The conductor material is nearly always an aluminum alloy, made into several strands and possibly reinforced with steel strands. Copper was sometimes used for overhead transmission, but aluminum is lighter, yields only marginally reduced performance and costs much less. Overhead conductors are a commodity supplied by several companies worldwide
Today, transmission-level voltages are usually considered to be 110 kV and above. Lower voltages, such as 66 kV and 33 kV, are usually considered subtransmission voltages, but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution. Voltages above 765 kV are considered extra high voltage and require different designs compared to equipment used at lower voltages.
Electric power can also be transmitted by underground power cables instead of overhead power lines. Underground cables take up less right-of-way than overhead lines, have lower visibility, and are less affected by bad weather. However, costs of insulated cable and excavation are much higher than overhead construction. Faults in buried transmission lines take longer to locate and repair.
In some metropolitan areas, underground transmission cables are enclosed by metal pipe and insulated with dielectric fluid (usually an oil) that is either static or circulated via pumps. If an electric fault damages the pipe and produces a dielectric leak into the surrounding soil, liquid nitrogen trucks are mobilized to freeze portions of the pipe to enable the draining and repair of the damaged pipe location. This type of underground transmission cable can prolong the repair period and increase repair costs. The temperature of the pipe and soil are usually monitored constantly throughout the repair period
Transmission efficiency is greatly improved by devices that increase the voltage (and thereby proportionately reduce the current), in the line conductors, thus allowing power to be transmitted with acceptable losses. The reduced current flowing through the line reduces the heating losses in the conductors. According to Joule's Law, energy losses are directly proportional to the square of the current. Thus, reducing the current by a factor of two will lower the energy lost to conductor resistance by a factor of four for any given size of conductor.
The optimum size of a conductor for a given voltage and current can be estimated by Kelvin's law for conductor size, which states that the size is at its optimum when the annual cost of energy wasted in the resistance is equal to the annual capital charges of providing the conductor. At times of lower interest rates, Kelvin's law indicates that thicker wires are optimal; while, when metals are expensive, thinner conductors are indicated: however, power lines are designed for long-term use, so Kelvin's law has to be used in conjunction with long-term estimates of the price of copper and aluminum as well as interest rates for capital.
The synchronous grids of the European Union.
IE rules
Rule 28 Voltage
Rule 30 Service Lines and apparatus on consumer premises.
Rule 31 Cut-out on consumer’s premises.
Rule 46 Periodical inspections and testing of consumer’s installation.
Rule 47 Testing of consumer’s installation.
Rule 54 Declared voltage of supply to consumer.
Rule 56 Sealing of meters and cut-outs.
Rule 57 Meters, maximum demand indicators and other apparatus on
consumer Premises.
Rule 77 Clearance above ground of the lowest conductor.
Rule 79 Clearance from buildings of low and medium voltage lines and
service lines.
Rule 87 Line crossing or approaching each other.
Rule 88 Guarding.
- Conditions and Requirements for Domestic, Commercial and Industrial Installation – steps to be followed in preparing electrical estimate (domestic, industrial and agricultural installation)
Residential single bed room Flat (1BHK).
Industrial power wiring having 4 or 5 machines.
School building having 3 class rooms.
Primary Health Centre having minimum 6 rooms.
Lighting scheme of a party hall having minimum 20 twin TL
fittings.
Erection of one no. 15hp induction motor in Saw mill / Flour mill.
Irrigation Pump motor (5hp) wiring.
Computer centre having 10 computers, a/c unit, UPS, light and fan.
Street Light service having 12 lamp light fittings
3 phase Service connection to a building having 5 kW load.
Types of Electrical Isolators
The electrical isolators are classified based on the requirement of the system which includes the following.
Double Break Type Isolator
Single Break Type Isolator
Pantograph Type Isolator
Then divide the load from a system with isolator opening
Close the earth switch. Earth switch can become with an interlock system with isolator. That’s means when isolator is open only that time earth switch can be closed.
Closing Operation of Electrical Isolator
Detach the earth switch.
Shut the isolator.
Shut the circuit breaker.
But these two have a similar principle like disconnection for isolating the parts of electrical circuit form the system. This cannot function in an on-load situation where there is any fault occurs in the system then the circuit breaker will trip routinely.
The circuit breaker is like an MCB or ACB that trips the complete system if there is an error occurs
Withstand Capacity
Isolators have the small withstand capacity when contrasted to Circuit Breaker.
Circuit breakers have the high withstand capacity at the condition of ON-load.
An insulator is one type of detaching switch which works under the condition of off-loading. It separates the circuit part in which the error takes place from the power supply. Isolators are applicable for high voltage devices like transformers. The main function of Isolator is, it blocks the DC signals & allows the AC signals to flow.
Circuit Breaker is one kind of protection device which works like a switch. When the fault happens in the system, it opens as well as closes the circuit contact. It separates the circuit automatically when a short circuit or overload takes place.
The applications of Isolators involve in high voltage devices such as transformers.
These are protected with a locking system on the external or with a lock to stop accidental usage.
Isolator in Substation: When a fault occurs in a substation, then isolator cuts out a portion of a substation.
Most transmission lines are high-voltage three-phase alternating current (AC), although single phase AC is sometimes used in railway electrification systems. High-voltage direct-current (HVDC) technology is used for greater efficiency over very long distances (typically hundreds of miles). HVDC technology is also used in submarine power cables (typically longer than 30 miles (50 km)), and in the interchange of power between grids that are not mutually synchronized. HVDC links are used to stabilize large power distribution networks where sudden new loads, or blackouts, in one part of a network can result in synchronization problems and cascading failures.
Electricity is transmitted at high voltages (66 kV or above) to reduce the energy loss which occurs in long-distance transmission. Power is usually transmitted through overhead power lines. Underground power transmission has a significantly higher installation cost and greater operational limitations, but reduced maintenance costs. Underground transmission is sometimes used in urban areas or environmentally sensitive locations.
Overhead transmission
High-voltage overhead conductors are not covered by insulation. The conductor material is nearly always an aluminum alloy, made into several strands and possibly reinforced with steel strands. Copper was sometimes used for overhead transmission, but aluminum is lighter, yields only marginally reduced performance and costs much less. Overhead conductors are a commodity supplied by several companies worldwide
Today, transmission-level voltages are usually considered to be 110 kV and above. Lower voltages, such as 66 kV and 33 kV, are usually considered subtransmission voltages, but are occasionally used on long lines with light loads. Voltages less than 33 kV are usually used for distribution. Voltages above 765 kV are considered extra high voltage and require different designs compared to equipment used at lower voltages.
Underground transmission
Electric power can also be transmitted by underground power cables instead of overhead power lines. Underground cables take up less right-of-way than overhead lines, have lower visibility, and are less affected by bad weather. However, costs of insulated cable and excavation are much higher than overhead construction. Faults in buried transmission lines take longer to locate and repair.
In some metropolitan areas, underground transmission cables are enclosed by metal pipe and insulated with dielectric fluid (usually an oil) that is either static or circulated via pumps. If an electric fault damages the pipe and produces a dielectric leak into the surrounding soil, liquid nitrogen trucks are mobilized to freeze portions of the pipe to enable the draining and repair of the damaged pipe location. This type of underground transmission cable can prolong the repair period and increase repair costs. The temperature of the pipe and soil are usually monitored constantly throughout the repair period
Bulk power transmission
Transmission efficiency is greatly improved by devices that increase the voltage (and thereby proportionately reduce the current), in the line conductors, thus allowing power to be transmitted with acceptable losses. The reduced current flowing through the line reduces the heating losses in the conductors. According to Joule's Law, energy losses are directly proportional to the square of the current. Thus, reducing the current by a factor of two will lower the energy lost to conductor resistance by a factor of four for any given size of conductor.
The optimum size of a conductor for a given voltage and current can be estimated by Kelvin's law for conductor size, which states that the size is at its optimum when the annual cost of energy wasted in the resistance is equal to the annual capital charges of providing the conductor. At times of lower interest rates, Kelvin's law indicates that thicker wires are optimal; while, when metals are expensive, thinner conductors are indicated: however, power lines are designed for long-term use, so Kelvin's law has to be used in conjunction with long-term estimates of the price of copper and aluminum as well as interest rates for capital.
IE rules
Rule 28 Voltage
Rule 30 Service Lines and apparatus on consumer premises.
Rule 31 Cut-out on consumer’s premises.
Rule 46 Periodical inspections and testing of consumer’s installation.
Rule 47 Testing of consumer’s installation.
Rule 54 Declared voltage of supply to consumer.
Rule 56 Sealing of meters and cut-outs.
Rule 57 Meters, maximum demand indicators and other apparatus on
consumer Premises.
Rule 77 Clearance above ground of the lowest conductor.
Rule 79 Clearance from buildings of low and medium voltage lines and
service lines.
Rule 87 Line crossing or approaching each other.
Rule 88 Guarding.
- Conditions and Requirements for Domestic, Commercial and Industrial Installation – steps to be followed in preparing electrical estimate (domestic, industrial and agricultural installation)
Estimate the quantity of material required for
Residential single bed room Flat (1BHK).
Industrial power wiring having 4 or 5 machines.
School building having 3 class rooms.
Primary Health Centre having minimum 6 rooms.
Lighting scheme of a party hall having minimum 20 twin TL
fittings.
Erection of one no. 15hp induction motor in Saw mill / Flour mill.
Irrigation Pump motor (5hp) wiring.
Computer centre having 10 computers, a/c unit, UPS, light and fan.
Street Light service having 12 lamp light fittings
3 phase Service connection to a building having 5 kW load.
What are the rules of electricity?
We've organized these principles into three basic rules: Rule 1 – Electricity will always want to flow from a higher voltage to a lower voltage. Rule 2 – Electricity always has work that needs to be done. Rule 3 – Electricity always needs a path to travelElectrical Isolator Definition, Working, Types of Isolator & Applications
The isolator is one type of switching device, and the main function of this is to make sure that a circuit is totally not triggered in order to perform the preservation. These are also recognizable like isolation switches to isolate the circuits. These switches are applicable in industrial, distribution of electrical power, etc. High voltage type isolation switches are utilized in substations for permitting isolation of equipment like transformers, circuit breakers. Usually, the disconnector switch is not proposed for circuit control but it is for isolation. Isolators are activated either automatically or manually. This article discusses an overview of electrical isolator, types and its applications.What is Isolator?
The isolator can be defined as; it is one type of mechanical switch used to isolate a fraction of the electrical circuit when it is required. Isolator switches are used for opening an electrical circuit in the no-load condition. It is not proposed to be opened while current flows through the line. Generally, these are employed on circuit breaker both the ends thus the circuit breaker repair can be done easily without any risk.Types of Electrical Isolators
The electrical isolators are classified based on the requirement of the system which includes the following.
Double Break Type Isolator
Single Break Type Isolator
Pantograph Type Isolator
Electrical Isolator Operation
The operation of electrical isolator can be done by the following two operational methods namely opening and closing.Opening Operation of Electrical Isolator
In the beginning, open the major circuit breaker.Then divide the load from a system with isolator opening
Close the earth switch. Earth switch can become with an interlock system with isolator. That’s means when isolator is open only that time earth switch can be closed.
Closing Operation of Electrical Isolator
Detach the earth switch.
Shut the isolator.
Shut the circuit breaker.
Difference between Isolator and Circuit Breaker
The main difference among the isolator as well as the circuit breaker is that the isolator detaches the circuit at the OFF-load situation while the circuit breaker detaches the circuit at the ON-load situation.But these two have a similar principle like disconnection for isolating the parts of electrical circuit form the system. This cannot function in an on-load situation where there is any fault occurs in the system then the circuit breaker will trip routinely.
The main differences between these two are discussed below.
Type of Device
An isolator is an off-load apparatus whereas circuit breaker is an ON-load apparatus.Operation
The operation of the isolator is manual whereas the operation of the circuit breaker is automatic.Device Action
The isolator is one type of mechanical apparatus which works like a switch whereas circuit breaker is an electronic apparatus made with BJT or MOSFET.Function
When a fault occurs in a substation, then isolator cuts out a portion of a substation. The other apparatus works without any intrusion.The circuit breaker is like an MCB or ACB that trips the complete system if there is an error occurs
Withstand Capacity
Isolators have the small withstand capacity when contrasted to Circuit Breaker.
Circuit breakers have the high withstand capacity at the condition of ON-load.
An insulator is one type of detaching switch which works under the condition of off-loading. It separates the circuit part in which the error takes place from the power supply. Isolators are applicable for high voltage devices like transformers. The main function of Isolator is, it blocks the DC signals & allows the AC signals to flow.
Circuit Breaker is one kind of protection device which works like a switch. When the fault happens in the system, it opens as well as closes the circuit contact. It separates the circuit automatically when a short circuit or overload takes place.
Applications of Isolator
The applications of isolator include the following.The applications of Isolators involve in high voltage devices such as transformers.
These are protected with a locking system on the external or with a lock to stop accidental usage.
Isolator in Substation: When a fault occurs in a substation, then isolator cuts out a portion of a substation.
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