# What is Star to Delta Connection?

## What is Star to Delta Connection?

Star and Delta Connections are the two types of connections in a 3 – phase circuits. A Star Connection is a 4 – wire system and a Delta Connection is a 3 – wire system. Hence, most of the power generated and distributed is actually a 3 – phase power (but majority of households will receive a single phase supply).

### What is the criteria for star delta transformation?

The relation of delta – star transformation can be expressed as follows. The equivalent star resistance connected to a given terminal, is equal to the product of the two delta resistances connected to the same terminal divided by the sum of the delta connected resistances.

#### What is the difference of Star and Delta?

In star connection, the line current is equal to the phase current, whereas in delta connection the line current is equal to root three times of the phase current. In star connection, phase voltage is low as 1/√3 times the line voltage, whereas in delta connection phase voltage is equal to the line voltage.

**How do you find line current in Delta Connection?**

Transformer Delta and Delta Connections In a delta connected ( Dd ) group of transformers, the line voltage, VL is equal to the supply voltage, VL = VS. But the current in each phase winding is given as: 1/√3 × IL of the line current, where IL is the line current.

**What voltage is a Delta Connection?**

Star connections are mainly required for the Power Transmission Network for longer distances, whereas in delta connection mainly in Distribution networks and is used for shorter distances. In star connection, each winding receives 230 volts and in delta connection, each winding receives 415 volts.

## What is the difference between Delta and star connection in motor?

In STAR Connection, the starting or finishing ends (similar ends) of three coils are connected together to form the neutral point. A common wire is taken out from the neutral point which is called Neutral. In DELTA Connection, the opposite ends of three coils are connected together.

### What is the difference between star and delta?

#### How do you find the equivalent resistance in delta connection?

The following equations represent the equivalent resistance between two terminals of delta network, when the third terminal is kept open.

- RAB=(R1+R3)R2R1+R2+R3.
- RBC=(R1+R2)R3R1+R2+R3.
- RCA=(R2+R3)R1R1+R2+R3.
- 2(RA+RB+RC)=2(R1R2+R2R3+R3R1)R1+R2+R3.
- RA=R1R2R1+R2+R3.
- RB=R2R3R1+R2+R3.
- RC=R3R1R1+R2+R3.
- RA=R1R2R1+R2+R3.

**What is the ratio of transformation of Star Delta Connection?**

Explanation: Star/star and delta/delta both connections have phase transfer ratio of x:1 and line transfer ratio also equal to x:1, while star/zig-zag star and delta/zig-zag star connections have line transformation ratio equal to 2/√3x:1. Sanfoundry Global Education & Learning Series – Transformers.

**When to use delta to star transformation equations?**

The resistors in between point 1, 2&3 are about to replace by a star connected system. Otherwise is difficult to find the total resistance. So we have to use the delta to star transformation equations.

## How to convert a Delta Network to a star network?

In this way, we can convert a delta network into a star network. Let us calculate the resistances of star network, which are equivalent to that of delta network as shown in the following figure. Given the resistances of delta network as R1 = 10 Ω, R2 = 60 Ω and R3 = 30 Ω.

### Do you have to replace Delta with Star?

This is very important. Though the tutorial problems guide you to find the replaceable systems, in practical level you will have to guide yourself manually. This means you must know how to choose the correct system to apply delta/star transformation. See the circled systems in the figure. You have to replace these systems with delta systems.

#### What are the resistances of the Delta Network?

Given the resistances of delta network as R1 = 10 Ω, R2 = 60 Ω and R3 = 30 Ω. We know the following relations of the resistances of star network in terms of resistances of delta network. Substitute the values of R1, R2 and R3 in the above equations.