What are slip rings in induction motor?

For an induction motor to produce torque, at least some difference should be there between stator field speed and rotor speed. This difference is called ‘slip’. The Slip Ring” is an electromechanical device that aids in transmitting power and electrical signals from stationary to a rotating component.

How does a slip ring motor works?

Slip rings on a wound rotor AC motor. Once the motor reaches operating speed, the brushes are lifted via the springs and the slip rings are short-circuited via the sliding contact bar. Adding resistance to the rotor windings brings the rotor current more in-phase with the stator current.

How does slip Help for rotation of induction motor?

“Slip” in an AC induction motor is defined as: As the speed of the rotor drops below the stator speed, or synchronous speed, the rotation rate of the magnetic field in the rotor increases, inducing more current in the rotor’s windings and creating more torque.

How is a slip ring motor started?

Slip-ring motors are invariably started by rotor resistance starting. Slip-ring motors are invariably started by rotor resistance starting. In this method, a variable star-connected rheostat is connected in the rotor circuit through slip rings and full voltage is applied to the stator winding as shown in Fig: 3.27.

What is the purpose of slip rings?

“A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. A slip ring can be used in any electromechanical system that requires unrestrained, intermittent or continuous rotation while transmitting power and / or data.

Why are slip rings used?

A slip ring is a method to make an electrical connection from a stationary object to a rotating assembly. These are used in many industrial automation applications and for equipment like tower and jib cranes, as well as cable and hose winders, where a portion can spin freely, while the base is fixed.

Where are slip rings used?

Which type of rotor is used in slip ring induction motor?

Compared to a squirrel-cage rotor, the rotor of the slip ring motor has more winding turns; the induced voltage is then higher, and the current lower, than for a squirrel-cage rotor. During the start-up a typical rotor has 3 poles connected to the slip ring. Each pole is wired in series with a variable power resistor.

What happens when slip is zero?

Zero slip means that rotor speed is equal to synchronous speed. If rotor is rotating at synchronous speed in the direction of rotating magnetic field the, there will be no flux cutting action, no emf in the rotor conductors, no current in rotor bar conductor and hence no development of electromagnetic torque.

Why is slip important in a motor?

In induction motor, slip is important because slip determines torque and also the machine behaviour. Explained as follows: (1) Torque depends on rotor power factor which, in turn, depends on slip. So, torque is lowest when slip(s) is equal to 1 i.e. at standstill.

Where is slip ring induction motor used?

The slip ring induction motors are also used for loads which require a gradual build-up of load. They are used for loads that requires speed control. Typical applications of wound rotor or slip ring induction motors are crushers, plunger pumps, cranes & hoists, elevators, compressors and conveyors.