# What does the dot mean on a current transformer?

## What does the dot mean on a current transformer?

The Dot Conversion (also known as the Dot Notation) is a polarity marking in a Transformer Phasing which is used to identify the phase relation between primary and secondary current and voltage in a transformer.

## Why do transformers use dot conventions?

The Dot convention is a type of polarity marking for transformer windings which describes the phase relationships in the transformer schematic diagrams. In this, the dots are mentioned on the primary and secondary windings of the transformer. By convention, the dot represents the positive polarity.

How do you find the dot convention?

Explanation. If the two currents flow into each dot or out of each dot, the mutual inductance (M) will be positive. On the other hand, if one current flows into a dotted end and the other leaves the dotted end, then the mutual inductance (M) will be negative.

### What is X1 in current transformer?

The Primary or Line side is designated with the letter ‘H’. The Secondary or Load side is designated with either the letter ‘X’ or ‘S’. X1 (White for 3090SCCTs), S1, or H1 is the positive wire. X2 (Black for 3090SCCTs), S2, or H2 is the negative wire.

### What is P1 and P2 in current transformer?

P1 indicates the side on which the current source is located, whilst P2 indicates the load side.

What is meant by dot convention?

Dot convention is a technique, which gives the details about voltage polarity at the dotted terminal. This information is useful, while writing KVL equations.

## What is Dot convention why it is used in the magnetic circuit?

The convention is as follows. If two terminals belonging to different coils in a coupled circuit are marked identically with dots then for the same direction of current relative to like terminals, the magnetic flux of self and mutual induction in each coil add together.

## What does dot on inductor mean?

(7) A dot convention is used to specify the direction of the windings around the core. Dots on the same ends of the inductor, like in figure 1, mean that the coils are wrapped clockwise- counterclockwise to each other.

What is 5P10 in CT?

If you see the specification or name plate of a protection class CT, you will find that it is given like 5P10. This CT can be interpreted as a protection class CT having an accuracy of 5% over a current range of 10 times of normal primary current rating.

### What is P1 P2 and S1 S2 of current transformer?

The connections of the primary winding are designated “K” and “L” or “P1” and “P2”, and the connections of the secondary winding are designated “k” and “l” or “S1” and “S2”. The polarity must be established such that the “flow direction of the energy” runs from K to L.

### What is 5P10 in current transformer?

What is coefficient of coupling in transformer?

Coefficient of coupling It is defined as the ratio of the number of magnetic flux lines common between two coils (inductors) to the number of magnetic flux lines in a coil.

## What is dot convention why it is required?

Dot Convention in Coupled Circuits is used to establish the choice of correct sign for the mutually induced voltages in coupled circuits.

Which is better 5P10 or 5P20?

Its application which differetiate the use of 5P10 and 5P20. If the breaker is used for backup protection say incommer etc you can use 5P20, but if it is say an incommer ACB/ MCCBof PMCC, you should use 5P10 only.

### What is 5P in CT?

The Number ‘5’ indicates the accuracy of the CT. When the current flows through the 5P20 protection class CT is 20 times of the rated primary current, the CT reads within the composite error of 5 %. If the current is above 20 times then the CT will saturate. Related Post: Accuracy Limit Factor(ALF) of CT.

### What is CT P1 and P2?

CTs are marked with P1 and P2 to indicate which way they should be fitted around the cable or buss-bar. The side marked P1 must point towards the generator, and P2 must point towards the load. If an arrow is printed on the CT it must point towards the load.