**REGULATING TRANSFORMERS:**

**REGULATING TRANSFORMER**:

The transformers which can vary voltage or phase angle of an output circuit are known as regulating transformer.In other word over all control of transformer is in our hand that is we can control current, voltage and phase angle.All the mentioned parameters are adjustable according to situation.

Regulation in a transformer can be made by following ways:

- Voltage regulating transformer
- Phase angle regulating transformer
- OLTC regulating transformer

Here we will discuss detail about voltage regulating transformer.

**VOLTAGE REGULATING TRANSFORMER: **

First of all we will know about voltage regulation,

VOLTAGE REGULATION:

The voltage regulation is defines as the percentage of voltage diffrence between no load voltages of a transformer with respect to full load voltage.

VOLTAGE REGULATION OF TRANSFORMER:

If a electrical power transformer is open circuited which means load is not connected with secondary terminal,in such situation the secondary terminal voltageof the transformer will be its secondary EMF that is E_{2}.And when full load is connected with secondary terminalof the transformer than rated current I_{2} folws through the secondary circuit,at the same time primary winding will also draw equivalent full load current from the source.The voltage drop in the secondary will be I_{2}Z_{2} in which Z_{2} is secondary impedence of transformer and now at same loading condition if we measure the voltage between secondary terminal we will get voltage V_{2} across load terminals which is less than no load secondary voltage E_{2} and this is due to I_{2}Z_{2} voltage drop in the transformer.

EXPRESSION FOR VOLTAGE REGULATING TRANSFORMER:

Here expression for voltage regulating transformer is represented by percentage that is

Voltage regulation(%)=E_{2}-V_{2}/V_{2}×100 %

**CAPABLITY CURVES FOR ALTERNATOR:**

Capablity curve for an alternator is plotted by taking P in the ordinate andQ in absicca,where P is the output power of alternator,Ş is tourque angle between two magnetic field.

Any operation within the boundary of the curve is safefrom heating and stability.If poi t S_{0} is located having active power P_{0} and Q_{0}the following results are available.

- S
_{0}=P_{0}+jQ_{0} - The machine will not geet over heated and will remain stable if S
_{0}is inside capablity curve - Ş or tourqe angle is the angle between Q-axis and the line drawn from S
_{0}to origin of field current I_{f}axis - Above the length of line2 is the measure of the field current required to operate at value of P=P
_{0}and Q=Q_{0}with rated terminal voltage - A line drawn from S
_{0}to the origin of Q axis will be at angle ő_{0}from the origin.

IMPORTANT QUESTIION:

1-Define regulating transformer?

Ans- The transformers which are used in which we can vary voltage or phase angle of an output circuit are known as regulating transformer

2-In how many ways regulation in a transformer can be maded?

Ans- Regulation in a transformer can be made by following ways:

- Voltage regulating transformer
- Phase angle regulating transformer
- OLTC regulating transformer

3-Define voltage regulation and describe voltage regulating transformer?

Ans- The voltage regulation is defines as the percentage of voltage diffrence between no load voltages of a transformer with respect to full load voltage. If a electrical power transformer is open circuited which means load is not connected with secondary terminal,in such situation the secondary terminal voltageof the transformer will be its secondary EMF that is E_{2}.And when full load is connected with secondary terminalof the transformer than rated current I_{2} folws through the secondary circuit,at the same time primary winding will also draw equivalent full load current from the source.The voltage drop in the secondary will be I_{2}Z_{2} in which Z_{2} is secondary impedence of transformer and now at same loading condition if we measure the voltage between secondary terminal we will get voltage V_{2} across load terminals which is less than no load secondary voltage E_{2} and this is due to I_{2}Z_{2} voltage drop in the transformer.

4-Write down the expression for voltage regulating transformer?

Ans- Voltage regulation(%)=E_{2}-V_{2}/V_{2}×100 %

5-Write down some conclusion of capablity curves for alternator?

Ans-Following conclusion were made:

- S
_{0}=P_{0}+jQ_{0} - The machine will not geet over heated and will remain stable if S
_{0}is inside capablity curve - Ş or tourqe angle is the angle between Q-axis and the line drawn from S
_{0}to origin of field current I_{f}axis - Above the length of line2 is the measure of the field current required to operate at value of P=P
_{0}and Q=Q_{0}with rated terminal voltage - A line drawn from S
_{0}to the origin of Q axis will be at angle ő_{0}from the origin