Ct And Pt Transformers.pdf

Voltage Transformer or Potential Transformer TheoryElectrical4U

It is connected to the meter or instrument. Generally, current transformers are expressed in their primary to secondary current ratio. You can transform the voltage or current down with a transformer whose turns ratio is accurately known, then measuring the stepped down magnitude with a normal range instrument.

Circuit Globe All about Electrical and Electronics. The primary terminal of the potential transformer is connected to the line for measuring the line voltage. The original magnitude can be determined ct and pt transformers just multiplying the result with the transformation ratio. Some other differences between the current and the potential transformer are explained below in the comparison chart. Current transformers are generally used to measure currents of high magnitude.

These transformers reduce the voltage and current from high value to the low value which can be measured by conventional instruments. One of the major difference between them is that the current transformer convert the high value of current into low value whereas the potential or voltage.


Secondary Winding It is connected to the current winding of the instrument. There are several types of differences between the voltage and the current transformer.

Clampmeter utilizing a split core A current clamp uses a current transformer with a split core that can be easily wrapped around a conductor in a circuit. Ring-type transformers usually use dry insulation systems, with a hard rubber or plastic case over the secondary windings. These transformers have large number of primary turns and smaller number of secondary turns. Thus the current transformer steps up increases the voltage while stepping down lowering the current.

Newer Post Older Post Home. Connection Connected in series with the instrument Connected in parallel with the instrument.

The line current is too high, and it is very difficult to measure them directly. This is a simplest form of potential transformer definition. Recieve free updates Via Email! Where a metal shield is present in the cable jacket, it must be terminated so no net sheath current passes through the ring, to ensure accuracy.

Current Transformer (CT)

This transformed voltage across the secondary winding will again drop due to the internal impedance of the secondary, before appearing across burden terminals. Transform the voltage from high value to the low value. Just like the transformer used for stepping down purpose, potential transformer i.

Instrument transformer

The current transformer is mainly used for relay protective scheme because it reduces the high magnitude of primary current to the suitable value for relay operation. Only the net ct and pt transformers current produces a secondary current ct and pt transformers this can be used to detect a fault from an energized conductor to ground. Current transformers used to sense ground fault zero sequence currents, such as in a three-phase installation, may have three primary conductors passed through the ring.

For temporary connections, a split ring-type current transformer can be slipped over a cable without disconnecting it. The current transformer also provides insulation against the high voltage of the power circuit and hence protect the apparatus and personnel from high voltage. The primary of the current transformer is connected directly to the line whose value is to measure.

Instrument Transformers - CT and PT

The primary winding consists the full line voltage. This primary emf will transform to the secondary winding by mutual induction and transformed emf is E s.

These transformers step down the current to be measured, so that it can be measured with a normal range ammeter. Ring-type current transformers ct and pt transformers installed over a bus bar or an insulated cable and have only a low level of insulation on the secondary coil. The secondary of the current transformer is connected to the ammeter or meter which measured the line value regarding fractions. Current transformers are often constructed by passing a single primary turn either an insulated cable or an uninsulated bus bar through a well-insulated toroidal core wrapped with many turns of wire.

Home Electrical machines Power system Contact electricaleasy. The secondary winding has large number turns accurately wound for a specific turns ratio. Because the gaps in the hinged segment introduce inaccuracy, confessions of a gp pdf such devices are not normally used for revenue metering.

Instrument Transformers

Current Transformer (CT)

Has a small number of turns and can be open circuit. The primary winding may be just a conductor or a bus bar placed in a hollow core as shown in the figure. Voltage Transformer or Potential Transformer Theory A voltage transformer theory or potential transformer theory is just like a theory of general purpose step down transformer.

The potential transformer reduced the high value of voltage into the small value which can easily be measured by the voltmeter or meter. Ct and pt transformers potential transformer reduced the high value of voltage into ct and pt transformers small value which can easily be measured by the voltmeter or meter. The core of the potential transformer is made up with high operating core operating at low flux densities.