its not necessary to use only Delta type T/F at receiving end, we can also used star type but in this case at same voltage level two star neutral point create due to which Harmonic create for avoiding this we prefer opposite combination at sending end and receiving end.

bcoz at the transmission side especially for secondary distribution we need neutral wire for getting single phase supply and star type is only one which provide neutral. at receiving side to step up voltage we need delta type connection.

Each AC and DC machine having its own characteristics.According to the reguirement, the motors will be selected. Also the availability of supply is taken into consideration. But normally AC is preffered than DC due to its low maintenance and relaiability.

Take an eg. of DC series motor, it's properties are suitable for Railway engine, at the start it has high torque and low speed and once the core gets saturated it's torque is low but the speed is higher, so for this kind of special requirement we require DC M/C

Current & voltage both requires for utilisation. Current depents on device for its energirising. Each individual device reqiures currents for its own working. But voltage is applied across device term...

As pressure in pneumatic sysytem is analogaus to voltage that's why the coil connected to supply voltage in wattmeter is called pressure coil.
 

The previous answers are right + to make an accurate measurement O.C test on LV side because the current is high on the low voltage so when we repeat the experiment we will get more results with the ...

Because during OC test, rated voltage is applied, hence the HV side is unsuitable to keep instruments, hence it is the HV side that is opened and the LV side is where instruments are placed (at their rated values)

Transformer noise is caused by the phenomenon magnetostriction. When a piece of any magnetic sheet is placed in the magnetic field it gets magnetised and elongate. But when the magnetic field is remov...

Because of the airgaps between stampings of the core.

To find out the losses under normal operating condition.

Normally the OC test is done to find out the losses. The losses depends on the voltage and frequency applied to the machine. So that while testing, the rated voltage and frequency are applied to the machine.