 Hello friends, I hope all of you are fine. In today’s tutorial, we are gonna have a look at Open Circuit Test and Short Circuit Test of Synchronous generator and their relationship. There are many factors of electrical power network rely on the usage of the generator models for the estimation of the power system behavior, the correctness of these estimations relies on the correctness of the parameters of the generator using in the system. Some of these parameters are not easy to find so producers of the generators mentioned these parameters on the datasheet.

In today’s post, we will have a look at different parameters of a synchronous generator that should be examined before installation of the generator. To easy understating of the parameter of a generator, you must have knowledge of the synchronous generator resultant circuit. So, let’s get started with the Open Circuit Test and Short Circuit Test of Synchronous generator.

#### Open Circuit Test and Short Circuit Test of Synchronous generator

• During the measurement of the resultant circuit of the synchronous generator, we find the three parameters, that are very important to study the complete performance of the real world synchronous generator.
• These three parameters are described here.

#### Open Circuit Test of the Synchronous Generator

• To accomplish this test the generator should move at its rated speed, no-load should be at its terminals, and the value of the field winding current should be 0.
• After following these steps, we will vary the field current step by step and calculate the terminal voltage at each step.
• As there is no load at the output terminals of the generator, so there will be zero armature current.
• Hence the internal generated voltage EA will equal to the phase voltage Vø.
• By using this data, we can construct the curve among the internally generated voltage that equals the terminal voltage and the field current.
• This graph between EA and the field current is known as the open-circuit characteristic (OCC) of the synchronous generator.
• By this graphical representation, we can find the value of internal generated voltage EA any value of the field current.

#### Short circuit test of Synchronous Generator

• To understand this straight-line behavior let’s have a look at the equivalent circuit of the synchronous generator when it is short-circuited this circuit is shown below. • From this circuit, you can find the value of the armature current (IA) that is given here.

IA =EA/(RA+jXs)

• The magnitude of the armature current is given here,

IA =EA/√(R2A+X2s)

Zs = √(R2A+X2s)

= EA/IA

• As we know that synchronous reactance Xs is greater than the armature resistance RA so this equation becomes.

Xs= EA/IA

= Vø,oc/IA

• If the value of the internally generated voltage (EA) and armature current (IA) is known, we can compute the value of the synchronous reactance.
• Measure the internal generated voltage EA from the open-circuit characteristic (OCC) at the specified value of the field current.
• Measure the short-circuited current IA at the field current from the open-circuit characteristic (OCC)
• Put the values of the internal generated voltage EA and the IA in given below equation and find the value of the synchronous reactance.

Xs= EA/IA

• There is some issue for this technique to the measurement of the synchronous reactance.
• As the internal generated voltage EA is measured from the OCC at that point where the generator is partly saturated for a higher value of the field current and the armature current (IA) taken from the SCC where the generator is un-saturated for all values of the field current.
• So, at the larger field current, the internal generated voltage calculated from the OCC at a specified value of the IF is not similar to the internal generated voltage measured from the SCC at the same value of the field current IF.
• This difference affects the value of the synchronous reactance X
• So, the result by this method can be applied to the saturation point, the unsaturated XS can be measured by this equation at any value of the IF in the straight-line part of the open-circuit characteristic (OCC).

Xs= EA/IA

#### Short-Circuit Ratio Synchronous Generator

• It is the ratio of the field current needed for the rated voltage at open-circuited conditions to the field current needed to produce rated armature current at short-circuited conditions.
• Though the short-circuit ratio tells nothing new that is not we know about synchronous generator reactance. But in industries, this fact is used so we should have knowledge of it.

You can also read some related topics to a synchronous generator that is listed here.

Introduction to Synchronous Generator

Synchronous Generator Equivalent Circuit

Synchronous Generator Phasor Diagram

Synchronous Generator Power and Torque

Synchronous Generator Operating Alone

Synchronous Generator Parallel Operation

Synchronous Generator parallel with Large Power system

Synchronous Generator Parallel with same Size Generator

Synchronous Generator Ratings

Synchronous Generator Capability Curves

Synchronous Generator Transients

That is the detailed article on the Synchronous Generator Parameter we did different tests for finding different parameters if you have any query ask in comments. See you in the next tutorial Synchronous Generator Operating Alone.

### 1 Comment

1. fleck water softener where to buy says:

We’re a gaggle of volunteers and starting a new scheme in our community.
Your site provided us with useful info to work on. You’ve performed a
formidable process and our entire neighborhood will probably be thankful to you.