Components of a substation and different types of transformers?

Components of a substation

The following components are used in the substation,

1. transformers
2. circuit breakers
3. switches and cutoffs
4. lightning arresters
5. Fences and gates

A transformer steps up incoming voltages and steps down outgoing voltages  respectively.
A circuit breaker protects power system against different surges.
Switches and Cutoffs help us in controlling flow of current in the power system.
A lightning arrester protects our power system against dangerous effects of storms.
In s substation fences and gates are used in order to secure the system from various damages.

 Transformer is made up of what

A device possessing shape of doughnut type having iron core with copper coils wound about or across opposite sides of the coil.The specific amount of current that flows through one side of coils generates magnetic field which then in turn creates current in the second side of coils inspite of the fact that there is no electrical contact between two sides of the coils.

What does  a transformer do

 A transformer performs transformation of specific amount of electrical energy from one specific circuit to an other specific circuit with the special feature that frequency before and after the transformation remains the same.However,transformer either increases or decreases AC voltage.

Types of transformers

The following are the types of the transformers normally used for respective functions and purposes.
power transformers

1. potential transformers
2. audio transformers
3. instrument transformers
4. 
   

Purpose of power transformers

Power transformers are employed in transmission of electric power and in electrical equipments or appliances too to convert main high voltage into local low voltage.
Types of power transformers

1. laminated core transformer
2. toroidal  core transformer

Brief function of above two transformers

Laminated core transformers  have lamination of some insulated material in order to reduce losses due to eddy currents produced in inner core.Whereas lower external field is present in toroidal transformers and they cover up less space as compared with laminated core transformers.

Purpose of potential transformer

A simple potential transformer enables us to monitor voltages of power line in single phase and three phase cases in power monitoring applications.

Types of potential transformer

• optical transformer
• capacitor transformer
• electromagnetic transformer

Brief function of above types
An optical transformer is configured when optical materials are used.
But capacitor and electromagnetic transformers are used when higher voltages applications are under discussion.

 Purpose of Audio transformers

Audio transformers are used for travelling of audio signals in different audio systems or circuits.
Furthermore audio transformers possess unique property of matching impedance between low and high impedance circuits.And audio transformers interlink components of professional audio systems.

Instrument transformers

Instrument transformers are employed for the operation of different instruments by using high voltages lines or high current circuits.

Types of instrument transformers

• Potential transformers
• current transformers

Brief function of above types

Potential transformers with the combination of voltmeter help us in measuring voltage in AC.
While current transformers with the combination of ammeter help us in measuring current in AC.

Power transformers

Laminated core

Laminated core transformer
This is the most common type of transformer, widely used in electric power transmission and appliances to convert mains voltage to low voltage to power electronic devices. They are available in power ratings ranging from mW to MW. The insulated laminations minimizes eddy current losses in the iron core.

Small appliance and electronic transformers may use a split bobbin, giving a high level of insulation between the windings. The rectangular cores are made up of stampings, often in E-I shape pairs, but other shapes are sometimes used. Shields between primary and secondary may be fitted to reduce EMI (electromagnetic interference), or a screen winding is occasionally used.

Small appliance and electronics transformers may have a thermal cut-out built into the winding, to shut-off power at high temperatures to prevent further overheating.

Toroidal

Toroidal transformer
Doughnut shaped toroidal transformers save space compared to E-I cores, and sometimes to reduce external magnetic field. These use a ring shaped core, copper windings wrapped round this ring (and thus threaded through the ring during winding), and tape for insulation.

Toroidal transformers have a lower external magnetic field compared to rectangular transformers, and can be smaller for a given power rating. However, they cost more to make, as winding requires more complex and slower equipment.

They can be mounted by a bolt through the center, using washers and rubber pads or by potting in resin.

Autotransformer

Main article: Autotransformer
An autotransformer has one winding that is tapped at some point along the winding. Voltage is applied across a portion of the winding, and a higher (or lower) voltage is produced across another portion of the same winding. The equivalent power rating of the autotransfomer is lower than the actual load power rating. It is calculated by: load VA × (|Vin – Vout|)/Vin. For example, an auto transformer that adapts a 1000 VA load rated at 120 Volts to a 240 Volt supply has an equivalent rating of at least: 1,000VA × (240V – 120V) / 240V = 500VA. However, the actual rating (shown on the tally plate) must be at least 1000 VA.

For voltage ratios that don't exceed about 3:1, an autotransformer is cheaper, lighter, smaller, and more efficient than an isolating (two-winding) transformer of the same rating.[2] Large three-phase autotransformers are used in electric power distribution systems, for example, to interconnect 33 kV and 66 kV sub-transmission networks.[citation needed]

Variable autotransformer

Variable autotransformer
Main article: Autotransformer § Variable autotransformers
By exposing part of the winding coils of an autotransformer, and making the secondary connection through a sliding carbon brush, an autotransformer with a near-continuously variable turns ratio can be obtained, allowing for wide voltage adjustment in very small increments..

Induction regulator

Main article: Induction regulator
The induction regulator is similar in design to a wound-rotor induction motor but it is essentially a transformer whose output voltage is varied by rotating its secondary relative to the primary—i.e., rotating the angular position of the rotor. It can be seen as a power transformer exploiting rotating magnetic fields. The major advantage of the induction regulator is that unlike variacs, they are practical for transformers over 5 kVA. Hence, such regulators find widespread use in high-voltage laboratories.

Polyphase transformer

A high-voltage transformer being dismantled

Cutaway view of a polyphase transformer
For polyphase systems, multiple single-phase transformers can be used, or all phases can be connected to a single polyphase transformer. For a three phase transformer, the three primary windings are connected together and the three secondary windings are connected together.[4] Examples of connections are wye-delta, delta-wye, delta-delta and wye-wye. A vector group indicates the configuration of the windings and the phase angle difference between them. If a winding is connected to earth (grounded), the earth connection point is usually the center point of a wye winding. If the secondary is a delta winding, the ground may be connected to a center tap on one winding (high leg delta) or one phase may be grounded (corner grounded delta). A special purpose polyphase transformer is the zigzag transformer. There are many possible configurations that may involve more or fewer than six windings and various tap connections.


Three-phase transformers 380kV/110kV and 110kV/20kV
Grounding transformer[edit]
Main article: Zigzag transformer
Grounding transformers let three wire (delta) polyphase system supplies accommodate phase to neutral loads by providing a return path for current to a neutral. Grounding transformers most commonly incorporate a single winding transformer with a zigzag winding configuration but may also be created with a wye-delta isolated winding transformer connection.

Leakage or stray field transformers

Leakage transformer
A leakage transformer, also called a stray-field transformer, has a significantly higher leakage inductance than other transformers, sometimes increased by a magnetic bypass or shunt in its core between primary and secondary, which is sometimes adjustable with a set screw. This provides a transformer with an inherent current limitation due to the loose coupling between its primary and the secondary windings. The output and input currents are low enough to prevent thermal overload under all load conditions—even if the secondary is shorted.

Uses

Leakage transformers are used for arc welding and high voltage discharge lamps (neon lights and cold cathode fluorescent lamps, which are series connected up to 7.5 kV AC). It acts then both as a voltage transformer and as a magnetic ballast.

Other applications are short-circuit-proof extra-low voltage transformers for toys or doorbell installations.

Resonant transformer

A resonant transformer is a transformer in which one or both windings has a capacitor across it and functions as a tuned circuit. Used at radio frequencies, resonant transformers can function as high Q_factor bandpass filters. The transformer windings have either air or ferrite cores and the bandwidth can be adjusted by varying the coupling (mutual inductance). One common form is the IF (intermediate frequency) transformer, used in superheterodyne radio receivers. They are also used in radio transmitters.

Resonant transformers are also used in electronic ballasts for fluorescent lamps, and high voltage power supplies. They are also used in some types of switching power supplies. Here often only one winding has a capacitor and acts as a tank circuit. The transformer is driven by a pulse or square wave for efficiency, generated by an electronic oscillator circuit. Each pulse serves to drive resonant sinusoidal oscillations in the tuned winding, and due to resonance a high voltage can be developed across the secondary.Courtesy of wikipedia....