What is nominal ratio of transformer?

The nominal ratio is defined as the ratio of rated primary quantity to the rated secondary quantity, either current or voltage. It is the ratio of transformation i.e. actual ratio to the nominal ratio. The ratio which is indicated on the name plate of a transformer is always its nominal ratio.

Herein, what is CT ratio in electrical?

A current transformer (CT) is a type of transformer that is used to measure alternating current (AC). It produces a current in its secondary which is proportional to the current in its primary.

What do you mean by CT ratio?

The ratio of a CT’s primary rating to its secondary rating is equal to the number of secondary turns. For example, a CT with a 5-A secondary and 20 turns will have a nameplate ratio of 100:5. This ratio is based on the primary conductor passing once through the transformer window.

What is transformer turns ratio test?

Turns ratio between the windings. The turns ratio test is performed on all taps of every winding. Power Transformer Turns Ratio Test. The Transformer Turns Ratio tester (TTR) is device used to measure the turns ratio between the windings (example shown below).

Why tap are provided on HV side of transformer?

Taps are provided at the HV windings of the transformer because of the following reasons. Taps are provided at the HV windings of the transformer because of the following reasons. The current on the low voltage winding of large transformers are high. Therefore interruption of high currents is a difficult task.

What is a ratio correction factor?

The term “ratio-correction factor” is defined as “that factor by which the marked (or nameplate) ratio of a current transformer must be multiplied to obtain the true ratio.” Usually, a family of such curves is provided for different typical values of burden.

What is a multiple tap transformer?

A Multi Tap Transformer is a step up or down transformer that has multiple taps on either the primary winding or the secondary winding. A Multi Tap Transformer provides flexibility in your input and output voltage requirements. Multi Tap Transformers are used in heating element applications.

What are the taps on a welding transformer?

A combination of primary and/or secondary taps on the welding transformer are commonly used to provide a macro adjustment of the welding current, as well as adjustment of secondary voltage.

What is a tap on a transformer?

A tap changer is a mechanism in transformers which allows for variable turn ratios to be selected in discrete steps. Transformers with this mechanism obtain this variable turn ratio by connecting to a number of access points known as taps along either the primary or secondary winding.

What does off nominal mean?

As “nominal” means “that has its nominal (aka normal) value”, the common word that comes to mind is abnormal. In writing, however, it is perfectly fine to refer to such a situation as off-nominal. This term is found in plenty of technical reports and manuals of aircraft.

Why the rating of transformer is in KVA?

Copper losses ( I²R)depends on Current which passing through transformer winding while Iron Losses or Core Losses or Insulation Losses depends on Voltage. So the Cu Losses depend on the rating current of the load so the load type will determine the powerfactor P.F ,Thats why the rating of Transformer in kVA,Not in kW.

Why tap changer is used in transformer?

A tap is a connection point along a transformer winding that allows a certain number of turns to be selected. This means, a transformer with a variable turns ratio is produced, enabling voltage regulation of the output. The tap selection is made with a tap changer mechanism.

Where is tap changer in transformer?

The purpose of a tap changer is to regulate the output voltage of a transformer by altering the number of turns in one winding and thereby changing the turns ratio of the transformer. There are two types of tap changers: a de-energized tap changer (DETC) and an on-load tap changer (LTC).

What makes a transformer hum?

Causes of electric hum. Electric hum around transformers is caused by stray magnetic fields causing the enclosure and accessories to vibrate. Magnetostriction is a second source of vibration, in which the core iron changes shape minutely when exposed to magnetic fields.

What is transformer noise?

Transformer noise is caused by a phenomenon which causes a piece of magnetic sheet steel to extend itself when magnetized. When the magnetization is taken away, it goes back to its original condition. This phenomenon is scientifically referred to as magnetostriction.

Why humming noise is produced in transformer?

The basic cause of transformer noise is magnetostriction: the expansion and contraction of the iron core (laminations) due to the magnetic effect of alternation current flowing through the transformer coils. This produces an audible hum.

What is the meaning of magnetostriction?

Magnetostriction is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization.

What is the effect of hysteresis loss in transformer machines?

Hysteresis loss is due to the reversal of magnetization of transformer core whenever it is subjected to alternating nature of magnetizing force .Whenever the core is subjected to an alternating magnetic field, the domain present in the material will change their orientation after every half cycle.

What is current loss?

Eddy Current Loss. When an alternating magnetic field is applied to a magnetic material an emf is induced in the material itself according to Faraday’s Law of Electromagnetic induction. These circulating currents are called Eddy Currents. They will occur when the conductor experiences a changing magnetic field.

What do you mean by iron loss in a transformer?

Eddy current loss and hysteresis loss depend upon the magnetic properties of the material used for the construction of core. Hence these losses are also known as core losses or iron losses. Hysteresis loss in transformer: Hysteresis loss is due to reversal of magnetization in the transformer core.

What is transformer efficiency formula?

Copper losses represents the greatest loss in the operation of a transformer. The intensity of power loss in a transformer determines its efficiency. The efficiency of a transformer is reflected in power (wattage) loss between the primary (input) and secondary (output) windings.

How can we minimize the core losses in a transformer?

Core losses majorly include Hysteresis loss and eddy current loss. Eddy Current loss can be reduced by increasing the number of laminations. The laminations provide small gaps between the plates. As it is easier for magnetic flux to flow through iron than air or oil, stray flux that can cause core losses is minimized.

What do you mean by CT ratio?

The ratio of a CT’s primary rating to its secondary rating is equal to the number of secondary turns. For example, a CT with a 5-A secondary and 20 turns will have a nameplate ratio of 100:5. This ratio is based on the primary conductor passing once through the transformer window.

Originally posted 2022-03-31 05:34:40.