(1) Smoke or fire occurs in the generator or exciter, or a hydrogen explosion occurs in the generator.
(2) The main transformer and the high-power transformer have serious defects and need to be shut down urgently.
(3) The generator sealing oil is interrupted and cannot be restored quickly.
(4) A strong ring spark occurs in the slip ring of the generator or main exciter and cannot be eliminated.
(5) The generator vibrates strongly (far exceeding the specified allowable value).
(6) The steam turbine tripped but the generator main circuit breaker did not trip.
(7) Other accidents endangering the safety of people and equipment occur.
1. When the load is symmetrical, the magnetomotive force ofthe armature affects the fundamental wave of the magnetic field of the main pole. This phenomenon is called armature reaction.
Assume that the only magnetomotive force acting on the DC generator is generated by the stator magnetic field. However, the current in the armature winding also creates a strong magnetomotive force which distorts and weakens the magnetic field produced by the magnetic field. This distortion and weakening of the magnetic field occurs in both motors and generators. The reaction caused by the magnetomotive force of the armature is generally called armature reaction.
2. The armature reaction has a great influence on the operation of the DC motor, which strengthens the magnetic field on one half of the magnetic pole and weakens the magnetic field on the other half. , the stronger the distortion of the magnetic field caused by the armature reaction, and the result is that it destroyswill interfere with the normal switching of armature winding components, easily cause sparking, and worsen the operating conditions of the motor. At the same time, the reaction of the armature will make the magnetic flux dense at the end of the pole piece, which will make the maximum voltage between the collector segments too high, which can also easily cause sparking and even cause a ring fire in the engine.
Install additional magnetic poles to compensate for distorted magnetic flux. For large motors, adding a compensation winding to the top of the main magnetic pole can correct the distortion in the magnetic flux distribution.
Detailed information:
The armature is the component of the electric motor that contains son. The relative movement of the wire through the magnetic field between the pole pieces causes an induced current dans the wire (as in a generator) or current passing through the wire causes magnetic induction, causing it to rotate in that magnetic field (as in. an electric motor). ?
Only DC motors have an armature. The armature includes an armature core and an armature winding. The armature winding is the circuit part of the DC motor. It also induces an electric potential and generates electromagnetic torque for electromechanical energy. conversion part (the generator is the conversion of mechanical energy into electrical energy). The armature core is part of the main magnetic circuit and sometimes the supporting component of the armature winding, and the armature winding is embedded in the slot of the armature core.
Baidu Encyclopedia - Armature Reaction