A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer's core, which induces a varying electromotive force (EMF) across any other coils wound around the same core. Electrical energy can be transferred between separate coils without a metallic (conductive) connection between the two circuits. Faraday's law of induction, discovered in 1831, describes the induced voltage effect in any coil due to a changing magnetic flux encircled by the coil.
Transformers are used to change AC voltage levels, such transformers being termed step-up or step-down type to increase or decrease voltage level, respectively. Transformers can also be used to provide galvanic isolation between circuits as well as to couple stages of signal-processing circuits. Since the invention of the first constant-potential transformer in 1885, transformers have become essential for the transmission, distribution, and utilization of alternating current electric power.A wide range of transformer designs is encountered in electronic and electric power applications. Transformers range in size from RF transformers less than a cubic centimeter in volume, to units weighing hundreds of tons used to interconnect the power grid.
An ideal transformer is linear, lossless and perfectly coupled. Perfect coupling implies infinitely high core magnetic permeability and winding inductance and zero net magnetomotive force (i.e. ipnp − isns = 0).[3][c]
A varying current in the transformer's primary winding creates a varying magnetic flux in the transformer core, which is also encircled by the secondary winding. This varying flux at the secondary winding induces a varying electromotive force or voltage in the secondary winding. This electromagnetic induction phenomenon is the basis of transformer action and, in accordance with Lenz's law, the secondary current so produced creates a flux equal and opposite to that produced by the primary winding.
The windings are wound around a core of infinitely high magnetic permeability so that all of the magnetic flux passes through both the primary and secondary windings. With a voltage source connected to the primary winding and a load connected to the secondary winding, the transformer currents flow in the indicated directions and the core magnetomotive force cancels to zero.
According to Faraday's law, since the same magnetic flux passes through both the primary and secondary windings in an ideal transformer, a voltage is induced in each winding proportional to its number of turns. The transformer winding voltage ratio is equal to the winding turns ratio.
An ideal transformer is a reasonable approximation for a typical commercial transformer, with voltage ratio and winding turns ratio both being inversely proportional to the corresponding current ratio.
The load impedance referred to the primary circuit is equal to the turns ratio squared times the secondary circuit load impedance.
The ideal transformer model neglects many basic linear aspects of real transformers, including unavoidable losses and inefficiencies.
(a) Core losses, collectively called magnetizing current losses, consisting of.
Hysteresis losses due to nonlinear magnetic effects in the transformer core, and
Eddy current losses due to joule heating in the core that are proportional to the square of the transformer's applied voltage.
(b) Unlike the ideal model, the windings in a real transformer have non-zero resistances and inductances associated with:
Joule losses due to resistance in the primary and secondary windings
Leakage flux that escapes from the core and passes through one winding only resulting in primary and secondary reactive impedance.
(c) similar to an inductor, parasitic capacitance and self-resonance phenomenon due to the electric field distribution. Three kinds of parasitic capacitance are usually considered and the closed-loop equations are provided
Capacitance between adjacent turns in any one layer;
Capacitance between adjacent layers;
Capacitance between the core and the layer(s) adjacent to the core;
Inclusion of capacitance into the transformer model is complicated, and is rarely attempted; the ‘real’ transformer model's equivalent circuit shown below does not include parasitic capacitance. However, the capacitance effect can be measured by comparing open-circuit inductance, i.e. the inductance of a primary winding when the secondary circuit is open, to a short-circuit inductance when the secondary winding is shorted.
Main article: Leakage inductance
The ideal transformer model assumes that all flux generated by the primary winding links all the turns of every winding, including itself. In practice, some flux traverses paths that take it outside the windings.Such flux is termed leakage flux, and results in leakage inductance in series with the mutually coupled transformer windings. Leakage flux results in energy being alternately stored in and discharged from the magnetic fields with each cycle of the power supply. It is not directly a power loss, but results in inferior voltage regulation, causing the secondary voltage not to be directly proportional to the primary voltage, particularly under heavy load. Transformers are therefore normally designed to have very low leakage inductance.
In some applications increased leakage is desired, and long magnetic paths, air gaps, or magnetic bypass shunts may deliberately be introduced in a transformer design to limit the short-circuit current it will supply. Leaky transformers may be used to supply loads that exhibit negative resistance, such as electric arcs, mercury- and sodium- vapor lamps and neon signs or for safely handling loads that become periodically short-circuited such as electric arc welders.
Air gaps are also used to keep a transformer from saturating, especially audio-frequency transformers in circuits that have a DC component flowing in the windings. A saturable reactor exploits saturation of the core to control alternating current.
Knowledge of leakage inductance is also useful when transformers are operated in parallel. It can be shown that if the percent impedance and associated winding leakage reactance-to-resistance (X/R) ratio of two transformers were the same, the transformers would share the load power in proportion to their respective ratings. However, the impedance tolerances of commercial transformers are significant. Also, the impedance and X/R ratio of different capacity transformers tends to vary.
Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer
A transformer designed to increase the voltage from primary to secondary is called a step-up transformer. A transformer designed to reduce the voltage from primary to secondary is called a step-down transformer.
Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer
Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer
Liquid-cooled (oil-filled) transformers use oil as the cooling and insulating medium. They are commonly used in high-voltage power transmission and distribution systems, as well as in industrial and commercial applications, where a higher power rating and increased efficiency is required.
Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformerThree phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer Three phases transformer
Simply put, Chinese New Year and Lunar New Year are not the same, although they are very much connected. In a casual conversation, both terms can be used interchangeably as synonyms. However, in a more strict cultural environment, it is necessary to understand the differences between the two.
Why is Chinese New Year not on the same day every year?
Chinese New Year is not on the same day every year because it is worked out according to the first day of the Chinese Lunar calendar. This means the year is determined by the movements of the sun and moon.
Why is red a significant colour in Chinese culture?
Use evidence from the text to support your answer. The colour red is very lucky to the Chinese as it symbolises fortune, good luck and joy. It is also the colour that, according to legend, scared away the Nian beast, ensuring the safety of the village.
Why is money given in even amounts?
Money is given in even amounts because odd numbers are believed to be bad luck in Chinese culture.
Why do you think lions and dragons are used for the dance in the parade rather than animals such as rabbits, cats and dogs? Lions and dragons are the most commonly used animals as part of the Chinese New Year parade dance as these costumes are bigger allowing more people to fit underneath them. Lions and dragons are big, fierce creatures, they can scare away evil spirits and bad luck.
In your own words, explain the legend of how Chinese New Year began. Pupils’ own responses, such as ‘According to Chinese legend, a village was attacked by a monster called the Nian, which ate their food, livestock and people. The villagers left food out for it but noticed that it was scared of a girl wearing red. They then used red lanters, scrolls and firecrackers to scare away the Nian and it never returned.’
Power transformers are used in transmission network of higher voltages for step-up and step down application (400 kV, 200 kV, 110 kV, 66 kV, 33kV) and are generally rated above 200MVA. Distribution transformers are used for lower voltage distribution networks as a means to end user connectivity.
Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer
High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer
Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer
High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer
Three phases transformer Liquid transformer Dry type transformer Surge arrester Lightning arrester Distribution transformer Power transformer Paid mounted transformer
High voltage switchgear Low voltage switchgear Skid mounted transformer Mother coil Silicone steel plate Single phase transformer
Three phases transformer
What are the implications of connecting different vector group like Dyn11 and Dyn5 distribution transformer in a network?
A Dyn11 and a Dyn5 have different vector groups so they can’t be paralleled directly by matching busings. However, using two phase rolls and different bushing connections, the vector groups can be matched.
First, here are the vector groups for a Dyn1, Dyn5 and Dyn11 when excited by counter clockwise, positive sequence, phase rotation ABC:
Note that the vector groups for the Dyn1 and Dyn5 are in phase with each other but the bushings don’t match—the Dyn5 lags the Dyn1. Also note that the output vector group of a Dyn1 lags a Dyn11 by 60º.
Here is where it gets interesting. When the phase rotation of the excitation source is reversed from ABC to ACB, the vector groups are mirrored as shown below (a phase rotation meter connected ABC would rotate in the negative direction; or if connected ACB, would rotate in the positive direction):
When these two sets of vector groups are compared, it becomes apparent that a Dyn11 vector group can be matched to a Dyn5 provided one of them has reverse phase rotation. There are two possible combinations.
Given a Dyn11 with positive sequence phase rotation ABC, a Dyn5 will have the same vector group if the phase sequence is rolled:
Can you see how to parallel these? The bushing match is A-A, B-C, C-B, a-c, b-b, c-a.
The second combination is derived by taking the Dyn5 as the reference. Given a Dyn5 with positive sequence phase rotation ABC, a Dyn11 will have the same vector group if the phase sequence is rolled:
The bushing match is the same: A-A, B-C, C-B, a-c, b-b, c-a.
So there are the implications of matching the vector groups of a Dyn11 and Dyn5. Now, please read the following disclaimer.
DON’T TRY TO PARALLEL YOUR TRANSFORMERS UNLESS YOU HAVE VERIFIED FOR YOURSELF THAT THE VECTOR GROUPS WILL MATCH.
WHEN YOU THINK YOU HAVE A MATCH, HAVE YOUR WORK VERIFIED.
MAKE SURE YOU USE PHASING STICKS TO MEASURE AND VERIFY THAT ALL VECTORS MATCH BEFORE CLOSING THE PARALLELING BREAKER.
USE A PHASE ROTATION METER TO VERIFY PROPER PHASE ROTATION FOR EACH TRANSFORMER BEFORE CLOSING THE PARALLELING BREAKER.
REMEMBER TO TAKE YOUR TIME AND BE SAFE!
What does Dyn11 mean on a transformer?
Dyn11 is vector group notation of tansformer.It means LV winding,
which is star connected (written in small letters means LV side and vice versa)is 30 degrees lagging by HV winding which is delta connected.
D = Delta connection at primary,y = Star connection at secondary and n = neutral point connected at secondary.
Dyn 11 means that the voltage of the secondary star winding lead the primary phase voltage by 30 degree and it corresponds to 11 o'clock.
Having a background in electrical engineering, you must know all types of electrical transformer symbols.
A transformer is an electrical machine(called in electrical engineering) or passive component(called in electronics engineering)
that transformer electrical energy from one circuit to another circuit with the help of faraday's law of electromagnetic induction.
In this article, we are going to see the symbol of transformer.
Here, you can see the symbol of a single phase transformer.
This symbol is used for single-line wiring diagrams. So, you must know this transformer's single line diagram symbol.
Here, the two circles indicate the two winding of the transformer.
These two circles are overlapped to each other because it indicates they are wound on the same core and magnetically connected to each other.
The upper and lower two lines indicate the primary and secondary winding terminals of the transformer.
Here, you can see the symbol of a three-phase transformer.
It is also almost the same as the single-phase transformer, just the difference is here,
three lines on both sides that indicate the three-phase terminals of the transformer.
Based on the core material Transformer is classified into main three types.
Iron Core Transformer is one of them. Here, you can see the symbol of Iron Core Transformer.
It also comes under the types of transformer classified based on the core material.
Here, you can see the symbol of Air Core Transformer
Variable Transformer is that where voltage can be varied either by providing tapings or changing the position of the transformer core.
Here, you can see the symbol of step down transformer.
Step Down transformer transfers the electrical energy by lowering the voltage and increase the current.
A step down transformer has more turns in primary winding than the secondary winding.
So, you can see the turns difference in primary and secondary winding in its symbolic diagram.
Step Up transformer increases the voltage but decreases the current in its secondary side.
Step Up transformer has fewer turns in primary winding than its secondary winding.
Here, you can see the symbol of autotransformer. An autotransformer has a single winding.
Tapping is provided for the output power supply.
Here, you can see the symbol of Isolation transformer.
The isolation transformer is that where both primary and secondary winding has the same turns and they carry the same voltage also.
The isolation transformer is used where proper isolation is required between two different power circuits.
It is an instrument transformer. Current transformer mainly used for measurement purpose, automation purpose, etc.
Here, you can see the symbol of potential transformer.
It is also an instrument transformer and used for measurement and control systems.
The voltage transformer is used everywhere such as power transformer, distribution transformer, etc.
Power transformers are used in power generating stations.
The main function of the power transformer is to step up the voltage for high voltage power transmission.
Power transformers are generally, Star-Delta connected,
which means they have star-connected winding in the primary side and delta-connected winding in the secondary winding.
Here, you can see the symbol of power transformer.
Distribution transformers are used on the consumer end.
The main function of the distribution transformer is to step down the voltage if required and distribute the electrical power with an electrical balance.
Generally, distribution transformers are Delta-Star connected, but they may be Star-Star connected also.
Here, you can see the symbol of Distribution Transformer.