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Basic ConceptsElectrical / Electronics SymbolsTransformer

Electrical Transformer Symbols – Single Line Transformer Symbols

Transformer Symbols – Single Line Transformer Symbols

Following is a list of different types of transformer symbols. The single line transformer symbols list is given below at the end of the post.

Transformer Symbols

Two Winding Transformer

Two winding Transformer Symbol

This is a generic symbol of a two winding transformer is single line representation. Two winding transformers are made up of two winding connected together through the varying magnetic flux.

Single Phase two Winding Transformer

Single Phase two winding transformer Symbol

This is SLD (single line diagram) representation of single phase two winding transformer. Such transformer has two winding i.e. primary and secondary both used by the single phase. It has two primary terminals and two secondary terminals.

Air Core Transformer

Air Core Transformer Symbol

These symbols represent air core transformer. An air core transformer has no magnetic core, instead the winding is wound around a plastic (nonmagnetic material) or there is no core at all. There are core losses in magnetic core that increases with frequency which is why air core transformer is used for radio frequency applications.

Saturable Reactor Transformer

Saturable Reactor Transformer Symbol

This is a type of transformer whose core can be saturated on purpose. Core saturation is the point where the core is fully magnetized and producing maximum flux. The core saturation is controlled using DC control winding.  During saturation, the reactance decreases that result in increasing of the current flow.

Iron Core Transformer

Iron Core Transformer Symbol

The core of this transformer is made up of iron. The iron has high magnetic permeability which allows it to carry high magnetic flux thus increasing the induction between the windings. The disadvantage of iron core is eddy current loss (core loss) which depends on supply frequency. Thus they are used for low frequency applications.

Ferrite Core Transformer

Ferrite Core Transformer Symbol

This symbol represents a transformer made up of ferrite core. The ferrite is a magnetic material having very high magnetic permeability which increases the flux inside the core of the transformer. Also ferrite has very low electrical conductivity which decreases the eddy current losses occurring inside the core.

Variable Transformer

Variable Transformer Symbol

A variable transformer is a type of transformer that can provide a variable secondary voltage from the same primary voltage. It can vary the output voltage by changing the number of turns or using different tap points or by variable coupling. A Variac is the most common variable autotransformer.

Single Phase Separate Winding Transformer

Single Phase Separate winding Transformer Symbol

This is an SLD representation of a single phase transformer with separate winding for primary & secondary terminals. The double dashed line represents two terminals for each winding.

Shielded Transformer

Shielded Transformer Symbol

Shielded transformer has an electrostatic shield between the primary & secondary winding that prevents the transfer of huge spikes of voltage & high frequency noise. The shield is grounded & The capacitance between the shield and the primary winding prevents the noise transfer due to high frequency.

Current Regulation Transformer

Current Regulation Transformer Symbol

Such type of transformer provides constant current even if the voltage increases or decreases. Storable core transformer regulates the current by saturation the core using DC control winding.

Voltage Regulation Transformer

Voltage Regulation Transformer Symbol

Voltage regulation of a transformer means maintaining the secondary voltage constant over a range of load. This kind of transformer regulate its voltage i.e. provide constant voltage with increasing or decreasing the load current.

Moving magnet Transformer

Moving magnet Transformer Symbol

As the name suggest, the voltage in this transformer coil is induced by the movement of the magnet in close proximity to the coil. Phono cartridge uses MM transformer & it converts the movement of the stylus into electrical signal by moving the magnet attached to its tips.

Adjustable Core Transformer

Adjustable Core Transformer Symbol

Such type of transformer has an adjustable core which increases or decreases the flux linkage between the windings to increase or decrease the current flow. Such type of transformers is used for current control in welding applications.

Current Transformer

Current Transformer Symbol

Current transformer is a type of instrument transformer used for decreasing high alternating current in a line down to safe levels for measurement purposes. The current produced in its secondary is proportional to the current in its primary (conductor) & it is measured by connecting it with a conventional Ammeter.

Dual Core Current Transformer

Dual Core Current Transformer Symbol

Such type of current transformer has two cores. There is a single conductor (primary) going though both of the cores of the transformer. The double core of the transformer increases the rating of the transformer.

Dual Core Current Transformer with Two Secondary Lines

Dual Core Current Transformer with Two Secondary Lines Symbol

This is a dual core current transformer that has two cores each with individual secondary winding. Each winding offers different turn ratio providing access to two different current ratings on each individual windings.

Current Transformer with 3 Conductors

Current Transformer with 3 Conductors Symbol

Such type of CT is also known as CBCT (Core Balance Current Transformer). It has 3 primary conductors (3 phases) running through its core. The total vector sum of the current in normal condition is zero. When there is an earth fault current, the difference appears through the CBCT which is connected to the alarm system.

Single Core CT with two Secondary & 3 Primary Conductors

Single Core CT with two secondary & 3 primary conductors Symbol

This symbol represents a current transformer having 2 secondary windings on a single core. There are 3 primary conductors running through its core. The individual secondary winding provides different current rating & turns ratio.

Single Core Current Transformer with two Secondary

Single Core Current Transformer with two secondary Symbol

Such type of Current transformer has two secondary winding on a single core. Each winding provide different turn ratio offering different current ratings.

Choke

Choke Symbol

Choke is a made up of two separate windings wounded on the same core in opposite direction. It is used for blocking high frequency current while it allows direct current & alternating current with low frequency.

Step Down Transformer

Step Down Transformer Symbol

A step down transformer is a type of transformer that converts high primary voltage into low secondary voltage. It also converts the low primary current into high secondary current. Step down transformer has Low number of turns in its secondary winding then its primary winding. The conversion depends on the turn ratio of the transformer.

Step Up Transformer

Step Up Transformer Symbol

The step up transformer converts the low primary voltage into high secondary voltage. It also converts the high primary current into low primary current. It is mostly used for line transmission to decrease the line losses occurring in the transmission line & also to meet the voltage requirement in a circuit. It has low number of primary turns then secondary turns.

Center Tapped Transformer

Center Tapped Transformer Symbol

A center tapped transformer has a tap point in the center of the secondary winding which let us access half the number of turns in the secondary winding. The voltage between the center tap point & any end of the winding is half of that of the full winding.

Transformer with Winding Polarity

Transformer with winding Polarity Symbol

The winding polarity in a transformer is denoted by the dot convention. if the current enters the primary dotted terminal, the voltage induced in the secondary dotted terminal will be positive. If the current leaves the primary dotted terminal, the voltage induced in the secondary dotted terminal will be negative. They are mostly used for connecting transformer in parallel to increase their capacity.

Three Winding Transformer

Three Winding Transformer Symbol

Apart from primary and secondary winding, there is another winding called tertiary winding which is why it is known as three winding transformer. Don’t confuse this with 3 phase transformer because 3 phase transformer has only 2 winding i.e. primary & secondary. The tertiary winding is used for providing reactive power where necessary or supplying auxiliary load with different voltage & power levels.

Autotransformer

Autotransformer Symbol

Such type of transformer has only one coil. The turns of the coil are divided in fixed proportion which acts as primary and secondary at the same time. there are no electrical isolation between the coil and the secondary voltage is the result of the self-induction as well as electrical conduction. Small size, lower cost & high efficiency is the main advantage of Autotransformer.

Single phase Autotransformer

Single phase autotransformer Symbol

This SLD symbol represents a single phase autotransformer. It has only single winding which is used by the same phase conductor. There are two input terminals as well as two output terminals taken from the same coil. They are used for single phase applications.

Variable Autotransformer

Variable Autotransformer Symbol

A variable autotransformer also known as Variac has a sliding brush that moves continuously across the winding increasing or decreasing the turn ratio of the transformer. The voltage in the secondary varies due to the changing turn ratio.

Iron Core Autotransformer

Iron Core Autotransformer Symbol

This symbol represents an autotransformer whose winding is wounded around the core made of iron. The iron core increases the magnetic flux which increases the self-induction between the turns.

Three Phase Voltage Transformer

Three Phase Voltage Transformer Symbol

This symbol represents a three phase voltage transformer. It is made up of 6 windings wounded around a single core. There are 3 windings on each side i.e. primary & secondary side. However the windings can be connected in any of these two most common configurations star or delta.

Three Phase Star-Star Connected Transformer

Three Phase Star-Star Connected Transformer Symbol

The primary windings & the secondary windings of such 3 phase transformer is connected together in star or wye configuration. Star configuration is a 4 wire 3 phase system where there is a neutral terminal.

3 Phase Transformer – Induction Regulator

3 Phase Transformer - induction regulator Symbol

Induction regulator is an AC electrical machine similar to an induction motor used for providing a continuous variable voltage. The primary & secondary windings are connected in series. Its output voltage depends on the turn ratio & it can provide continuous voltage ranging from 0 to maximum output voltage.

3 Single Phase Star/Star Connected Transformer

3 single phase star-star connected transformer Symbol

It is the symbol used for 3 single phase transformers whose primary and secondary both are connected in star formation. The star configuration is acquired by combining one end of all three windings to make a neutral point.

Three Phase Star Connected Autotransformer

Three phase star connected autotransformer Symbol

This symbol represents the star configuration is a three phase autotransformer. There are only three windings in a three phase autotransformer that acts as both primary and secondary winding. There may multiple tap points for variable secondary voltage.

3 Phase Star-Delta Connected Transformer

3 phase star-delta connected transformer Symbol

Also known as 3 phase wye-delta (or Star / Delta) transformer is a 3 phase transformer whose primary winding is connected together in star or wye configuration & the secondary winding is connected in delta configuration. It converts the three phase 3 wire system into three phase four wire system

3 Phase Delta-Star Connected Transformer

3 phase delta-star connected transformer Symbol

It is also known as delta-wye transformer & the primary winding of this transformer is connected in delta configuration and the secondary winding is connected in star or wye configuration. It converts the 4 wire (three phase) system into 3 wire (three phase) system.

3 Phase Star-Delta Connected Transformer with Tap Changer

3 phase star-delta connected transformer with tap changer Symbol

This symbol represent a 3 phase transformer connected in star-delta configuration with a tap changer. The tap changer is used for the regulation of the output voltage by changing the transformer turn ratio. The tap changer switches between many tap points providing variable turn ratios.

3 phase Star/Star Connected Transformer with Connection Points

3 phase star-star connected transformer with connection points Symbol

This is a 3 phase star-star connected transformer with multiple tap points for variable voltage. Each connection point provides fixed output voltage depending on the turn ratio with respect to the primary winding.

3 phase star-zig zag Connected Transformer

3 phase star-zig zag connected transformer Symbol

Such type of 3 phase transformer’s primary winding is connected in wye or star configuration and the secondary winding is connected in zig zag or “interconnected star ” configuration. Each phase of the zig zag transformer has two halves. The zig zag configuration provide a neutral for grounding or for supplying a single phase load.

Following is the list of single line transformer symbols.

Single Line Transformer Symbols

Related Electrical and Electronic Symbols:

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