yhdistelmäkäämittyjä

Yhdistelmäkäämittyjä, known in English as compound-wound or cumulative compound DC motors, are a type of direct current electric motor that utilizes two sets of field windings. These windings are connected in such a way that their magnetic fields add together, hence the term "cumulative compound". One field winding is in series with the armature, and the other is connected in parallel with the armature. This configuration provides characteristics that blend those of shunt and series wound DC motors.

The series winding provides a strong starting torque, similar to a series motor, because its magnetic field strength is directly proportional to the armature current. As the motor speeds up and the armature current decreases, the magnetic field from the series winding also weakens. The shunt winding, connected in parallel with the armature, provides a relatively constant magnetic field, similar to a shunt motor. This helps to regulate the motor's speed and prevents it from accelerating excessively.

The combination of these two windings results in a motor with good starting torque and relatively stable speed regulation under varying loads. Compound-wound motors are often used in applications where a high starting torque is required, but where the speed must not vary too drastically with load changes. Examples include elevators, punch presses, and some types of hoists. The exact performance characteristics can be adjusted by varying the relative strengths of the series and shunt field windings.