(1) Smoke or fire occurs in the generator or exciter, or a hydrogen explosion occurs in the generator.
(2) The main transformer and 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.
How to deal with sparking from generator carbon brushes
Let's talk about a complicated topic
Rotor: generatore a rotating magnetic field
Stator: stator The coil generates an alternating current in the changing magnetic field
Rectifier: rectifies the alternating current generated by the stator coil into a direct current at through a diode. The unidirectional conductivity of the diode
Capacitor: The friction between the slip ring and the carbon brush will produce sparks, which will produce electromagnetic interference. The capacitor is used to avoid interference.
Case: Generator support and mounting
That's it, I'm in the maintenance business. and I understand some simple generators quite well.
This can be excluded from the following points: 1. Check whether the brush length is too shortrte and reaches the lifeline, which makes the pressure too low and the brush cannot contact the slip ring; 2. Check whether the pressure of the spring pressure finger is appropriate. If it is too small, it will cause brush discharge. 3. Check the surface finish of the slip ring. If it is too hairy, it will increase the brush. contact resistance and cause large sparks; 4. Check the rotor electrical circuit to ensure that the resistance is normal and that there are no short circuits between turns. 5. Check whether the bearings are too large, causing the brushes to run out significantly; slip ring when the rotor turns. Check whether the radial runout on the slip ring surface is too large. The brush bounces and sparks; 6. In addition, if the brush conforms to the one used before, the brush has conductive current requirementsand friction speed. Preventive measures
1. Carbon brushes and slip rings should be inspected daily. The main inspection items are:
(1) The wear length of carbon brushes does not exceed 2. /3. When the wear length of the carbon brush exceeds 2/3 (that is, the top of the carbon brush and the top of the brush holder are on the same plane), it should be replaced.
(2) There is no spark from the carbon brush. When the carbon brush just begins to spark, it is necessary to find the cause and eliminate it in time.
(3) The carbon brush has no gap from the outside of the slip ring, and there is no crack at the edge of the carbon brush.
(4) The carbon brush braid is well connected to the brush holder and the carbon brush, and there is no heat or contact with the brush holder.
(5) The baThe carbon blade does not jump, shake or get stuck in the brush holder.
(6) Regularly use a DC clamp meter to measure the current sharing of each carbon brush evenly, and use an infrared thermometer to measure whether the carbon brushes are overheated when there is an abnormality .It should always be replaced in time.
(7) The spring pressure is normal and there is no deformation or breakage. Normally, the pressure on each carbon brush should be uniform and stable. The unit pressure is generally between 1.1 kg and 2.5 kg. The unequal pressure difference between carbon brushes should be less than 5%.
(8) The distance between the brush holder and the slip ring is the specified value. The distance between the generator brush holder and the slip ring: 2.5~3mm, the distance between the main excitation brush holder and the slip ring: 2~4mm.
(9) The surface of the slip ring should be free from discoloration, overheating and uneven wear, and the surface temperature of the slip ring should not exceed 120°C.
(10) Check if there is dirt on the brush holder and brush holder. If there is a lot of dirt, it should be swept away with a brush or blown out with compressed air.