Liukurengasmoottori

Liukurengasmoottori, also known as a slip ring motor, is a type of AC electric motor. Its rotor contains coils that are connected to slip rings. These slip rings, along with brushes, allow external electrical components to be connected to the rotor circuit. This is in contrast to a squirrel cage rotor, which has a permanently short-circuited rotor.

The primary advantage of a liukurengasmoottori is its ability to control the rotor's resistance. By adding external resistance through the slip rings and brushes, the starting torque can be increased, and the starting current can be reduced. This makes it suitable for applications where high starting torque is required, such as cranes, hoists, and large industrial machinery. Furthermore, the speed of the motor can be varied to some extent by adjusting the rotor resistance, although this method of speed control is not as efficient as other methods.

The construction of a liukurengasmoottori involves a stator, similar to that of a squirrel cage motor, and a rotor with windings. The ends of the rotor windings are brought out to a set of slip rings mounted on the motor shaft. Carbon brushes press against these slip rings, allowing electrical connection to the external circuit. When the motor is running at its normal operating speed, the slip rings are often short-circuited by a mechanism within the motor, effectively turning it into a simpler, more robust motor for steady-state operation. This design provides a balance between performance characteristics and operational simplicity.