We can increase the turning force (or torque) that the motor can create in three ways: either we can have a more powerful permanent magnet, or we can increase the electric current flowing through the wire, or we can make the coil so it has many “turns” (loops) of very thin wire instead of one “turn” of thick wire.

An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor’s magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor’s shaft.

We supply electrical energy to an electric motor. An efficient motor transfers most of this energy as kinetic energy (useful work). Energy is lost as the electric current flows through the motor’s coils.

(It is converted into kinetic energy by means of an electric motor. A motor works when an electric current passes through a wire in a magnetic field. The wire turns, and some of the electric energy is turned into kinetic energy.)

How do motors work? Electric motors work by converting electrical energy to mechanical energy in order to create motion. Force is generated within the motor through the interaction between a magnetic field and winding alternating (AC) or direct (DC) current. Electric Motors have an array of applications.

Look for the stator core construction and rotor. If there is no commutator, then it is a AC motor. If there is a commutator and brushes, it may be either a DC motor or an AC commutator motor (Universal motor).

AC motors are generally considered to be more powerful than DC motors because they can generate higher torque by using a more powerful current. However, DC motors are typically more efficient and make better use of their input energy.

Tesla, for example, uses alternating current (AC) induction motors in the Model S but uses permanent-magnet direct current (DC) motors in its Model 3. There are upsides to both types of motor, but generally, induction motors are somewhat less efficient than permanent-magnet motors at full load.

3 Point Starter is a device whose main function is starting and maintaining the speed of the DC shunt motor. The 3 point starter connects the resistance in series with the circuit which reduces the high starting current and hence protects the machines from damage.

The most significant difference between the three point and the four-point starter is that in three-point starter the no voltage coil (NVC) is connected in series with the field winding whereas in four-point starter the NVC is directly connected to the supply voltage.

What is a Three-point Starter? It is named as a 3-point starter because this starter has 3 terminals, one is L (line) linked to supply, one is F (field) linked to the field and the other is A (armature) linked to the armature.

series motor

Series wound DC motors are best for applications that require high startup torque, without the need for speed regulation. Like a shunt motor, as a load is applied to a DC series motor, the motor speed decreases, which reduces the back EMF and increases the net voltage.

Originally Answered: Why should a series motor never be started on no-load? Motor armature current is decided by the load. On light load or no load, the armature current drawn by the motor is very small. and on no load as Ia is small hence flux produced is also very small.

Applications include automotive, hoists, lifts and cranes as it has a high starting torque. Shunt Wound – This type has one voltage supply and the field winding is connected in parallel with the rotor winding and can deliver increased torque, without a reduction in speed by increasing the motor current.

1. What will happen if DC shunt motor is connected across AC supply? Explanation: In case of parallel field connection, it won’t rotate at all and will start humming and will create vibrations, as a torque produced by positive and negative cycle will cancel out each other. DC motor will be heated up and it may burn.

compound DC motor

It means your motor / rotational machine has high moment of inertia. Larger moments requiring more torque to rotate. For rotating machines (like electric motors, ic engines) if the moment of inertia is high, since the torque is rotational moment, starting torque will be higher.

The starting torque is the required amount of energy that is used to overcome the inertia of standstill. That is also known as pull-up torque it is the minimum torque generated by a motor to accelerate it from static position to the operating speed.

The 3600 RPM, 1HP motor produces 1.5 ft. lbs. of torque at 3600 RPM. So if your 1HP pump was operating at 1800 RPM, the 1800 RPM motor would be producing 3 ft.

The Locked Rotor Torque or Starting Torque is the torque an electrical motor develops when starting at zero speed. A high Starting Torque is more important for application or machines hard to start – like positive displacement pumps, cranes etc.

Starting torque is the torque transferred by the shaft coupling during run-up (see Start-up process). It is calculated based on the ratio of power (P) to angular velocity (ω) and is represented as a rotational speed function.

: the maximum torque a motor will carry without an abrupt drop in speed.

Starting torque = torque reqd to overcome friction, load inertia, stiction, etc., and accelerate the load inertia. This is meant to be a transient value. Running torque or load torque = less than starting torque, keeps the previously accelerated inertia + load at steady state speed.

The required torque is calculated by multiplying the sum of load torque and acceleration torque by the safety factor. When the required torque for the motor varies over time, determine if the motor can be used by calculating the effective load torque.

The starting torque of the motor is given by, At start, the rotor reactance is large because slip of the motor at start is equal to unity. The large rotor reactance at start makes the starting torque of the motor poor. The motor draws about 5 to 6 times current of its full load current and produce very less torque.

Starting Torque:- It is torque which is required to start the motor at load or at no load. It is available at the rotor shaft and denoted by Ts. Running Torque:- It is the torque which is required to run the motor at normal speed with load. It is also available at the rotor shaft.

Note that the torque is maximum when the angle is 90 degrees. A practical way to calculate the magnitude of the torque is to first determine the lever arm and then multiply it times the applied force. The lever arm is the perpendicular distance from the axis of rotation to the line of action of the force.

Hence, the developed torque is maximum when the rotor resistance per phase is equal to the rotor reactance per phase under running conditions. By putting the value of sX20 = R2 in equation (1) we get the equation for maximum torque.

1. Torque (lb.in) = 63,025 x Power (HP) / Speed (RPM)
2. Power (HP) = Torque (lb.in) x Speed (RPM) / 63,025.
3. Torque (N.m) = 9.5488 x Power (kW) / Speed (RPM)
4. Power (kW) = Torque (N.m) x Speed (RPM) / 9.5488.