ELECTRIC MACHINES || What is no load current on Xmer ? || Draw the circuit diagram for open circuit test on single-phase transformer ?||Describe sumpner`s test on transformer with neat diagram?||Draw the circuit diagram for load test on single phase Xmer?

What is no load current on Xmer ?

When the secondary winding of transformer is open (no load connected) and supply voltage source is connected to the primary side on Xmer , So the current is flowing in primary circuit is called no load current . which is represent by Io .

Draw the circuit diagram for open circuit test on single-phase transformer ?

Open circuit

Draw the circuit diagram for short circuit test on single-phase transformer ?

Short circuit

Describe sumpner`s test on transformer with neat diagram?

The open and short circuit test cannot be used foe the 'heat run' test wherein the purpose is to determine the steady temperature rise if the transformer was fully loaded continuously ; this is so because under each of these test the power loss to which the transformer is subjected is either the core loss or copper loss but not both . The way out of this impasse without conducting an actual loading test is the SUMPNER`s test which can only be conducted simultaneously on two identical transformer .

Sumpner`s test

Draw the circuit diagram for load test on single phase Xmer?

Circuit diagram for load test

GK_GOURAV

What Is Auto Transformer || Explanation ...

Auto Transformer :-

It is a type of Transformer , It`s working principle is same as normal transformer, which is   " FARADAY`S LAW OF ELECTOR-MAGNETIC INDUCTION " .
Which states that ;
' When a conductor is placed in a varying magnetic field, an EMF is induced which is known as Induced EMF. If the conductor circuit is closed, a current is
also induced which is known as Induced Current. It has two Windings  ;

             1.) Primary Winding ,
     2.) Secondary Winding.

In auto Transformer number of turns in primary winding is constant but we can change number of turns in the secondary winding with the help of a Rotating Disk.
So we are eligible to take output as much as we want under the capacity of the transformer.
We can represent Auto-Transformer by the following symbol :

AUTO Xmer

As we know ;

         N1/N2 = E1/E2

Means the induced voltage depends on the number of turns in the windings. We can change the output by changing the number of turns in the winding in the
Single Transformer.

VIDEO:-

Use :-

It is mainly used in laboratories in schools, colleges and research labs Because in labs we are used to work with different voltages, it is very useful
to work with An Auto-Transformer.

P-N JUNCTION DIODE

P-N JUNCTION DIODE :-

It is one of the most usable electronics element . It is made up of semiconductors of p- type and n- type, when we join both semiconductors it forms a junction between them, hence the junction is from this name.

This device has two terminals / electrodes one from n-type semiconductor and second from p-type semiconductor . Due to the two electrodes it is called DIODE, i.e. di + electrode.

To connect the external terminals , a metal is applied to the heavily doped n-type and p-type semiconductor. which is called ohmic contact.
The drop across the contact is very small which do not affect the performance of the device.

DIAGRAMS AND SYMBOLS :-

p-n junction diade

symbol

BIASING :- 

To operate the diode we need to know about the biasing .

our diode works short circuit when it is in the forward biased, means it pass current on it.
and when it is reverse biased it act as a open circuit, means it do not allow to pass current on it.
FORWARD BIASING:-
the p terminal of diode is connected to the positive terminal of the battery and the n terminal of diode is connected to the negative terminal of the battery.
shown the fig.


REVERSE BIASING:-
the n terminal of diode is connected to the positive terminal of the battery and the p terminal of diode is connected to the negative terminal of the battery.
shown the fig.

USE OF DIODE :-

It allow to flow current only in one direction so it is use in rectifier circuits.
And also to send information or signal in only one direction.

What is an LDR ? || How to use it in the circuit.

LDR :-

LDR is light-dependent resistor . It is a kind of variable resistance . It very automatic with respect to light . we can control it`s resistance with the help of light intensity.

It works on the photo-conductivity principle , and it is a passive element of electronics circuit .

Image of an LDR

It is made of a high resistance semiconductor.

Material use to make It ?

It is made from Semiconductor material , Which have most light Sensitive properties.

Mainly most of the LDR made up of Cadmium Sulphide ,(CdS)

VIDEO:-

IT`S RESISTANCE :-

In the time of dark means when LDE in the dark (low light intensity) it show high resistance in Mega ohms .
{so light intensity is inversely proportional to the resistance of LDE.}

And in the time of light means the intensity of light is high , so LDE show very low resistance in the order of ohms only.

UNIT OF LDR :-

It is a kind of resistance so its unit is same as resistance

which is OHM  𝞨 .

USE OF LDR :-

LDR is also a light sensing element in electronics.

* To make night light :-
It is a electric circuit which is made with the help of LDR. This circuit is use as a automatic switch.
When light fall on this circuit it off automatically and when the light intensity decrease on this circuit it on automatically.
[this circuit is works on both directions...]

We can use LDR in any light detecting circuits .
Like Light depending alarm system , Light depending switch , Light depending indicators ect.

RESISTANCE :-

RESISTANCE :-

It is the basic element of electrical and electronics instruments and machines .
Resistance can be define as a barrier in the way / path of current
in conductor (It is a single straight wire.).
We have a formula for finding the value of resistance , it is given
by scientist OHM . that is :-

V = IR                                                                                     R = V/I

It is Ohm`s law
where R = resistance of the conductor.
  V = voltage of the terminals of the conductor.
  I = current flowing in the conductor.

We can say that the ratio between voltage and current is define as resistance.

DIAGRAMS AND SYMBOLS OF RESISTANCE :-

Symbol of resistance are shown in fig. below;
We can use the symbol of resistance at the time of
circuit draw in paper.

  

SYMBOL

                                     

UNIT OF RESISTANCE :- 

Here the unit of resistance is OHM , is symbolic representation is
Greek word (omega) Ω

Where ohm = volt / ampere ;

USES OF RESISTANCE :-

Basically we use resistance to reduce current in some electronics
device.
1.) To protect device.
2.) Safety purpose.
3.) To reduce voltage.

VARIABLE RESISTANCE :-

this is A kind of resistance, but it can increase or decrease its
resistance.
is symbol and fig. shown below.

SYMBOL