The effect of a armature reaction is to- - Reduction of generated emf due to decrease in value of flux per pole. -The maximum value of gap flux density increases. -The armature reaction shifts brush axis from GNA

Negative sequence over current relays are used to detect the unbalanced load on a generator which may cause excessive rotor heating. The relay is also used to detect unbalanced load currents in motors.

Field winding in a DC motor is not a rotating part. It is present away from the motating part of the machine. So, temperature rise in the machine will not produce any effect on the machine rotation. Thuse field winding can sustain the maximum temperature rise.

ব্যাখ্যাঃ ট্রান্সফর্মারের Open সার্কিট টেস্ট হতে আয়রন লস এবং শর্ট সার্কিট টেস্ট হতে কপার লস বের করা হয়।

The direction of the induced emf is always such as to result in opposition to the change producing it. This law is known as Lenz's law

The art of welding refers to a fabrication process that causes coalescence between materials such as metals, thermoplastics and others. In welding, heat is used to melt the workpieces and a filler materials is used to form a weld pool or molten material.

When DC Motor routes on the action of driving torque, the conductors move through the magnetic field and hence emf induce the direction of this emf oppose to applied voltage. This is called as back emf.

Slip ring induction motor is a type of motor where its external circuit is connected using some rings. This rings attached with high resistance acts as an external circuit for the rotor. This external circuit helps in developing a high starting torque with low current

As increased load means that it requires more torque to turn at that speed. The motor is not producing that torque. So motor will slow or decrease a little bit.

E = V- laRa ⇒ 110 = 120-la x0.5 la = 20 A

The starting winding also known as the auxiliary winding is used to create the torque needed to start a single phase motor. The starting winding is placed in the stator and also parallel of rotor of the motor.

N₁= 120f/P = 120x50/4 = 1500 грm

They improve the waveform of generated EMF Le. generated EMF can be made to approximate to sine wave more easily and the distorting harmonics can be reduced or totally eliminated.

When the DC motor is connected across the supply without load then it will draw a small amount of current form supply. As low current will flow through the field winding as well as armature widing so main flux produced will be lesser. As, main flux is lower. speed will tend to increase. As speed increases back em also increases and thus current drawn from the supply will become more and more lower and thus main flux will also become more and more lower and thus speed will tend to increase more and more.

Power is measured in watt. Joules. Strength of current measured in Amperes. Ampere-hour is the unit of quantity of electricity of electric charge.