Answer: 1. The reasons why the rotor is grounded: 1) Personnel are working on the excitation circuit and the rotor is grounded due to accidental contact or others reasons. 2) Grounding caused by damaged rotor slip ring insulation, damaged rotor slot insulation, damaged rotor slot insulation and end insulation, damaged rotor cable insulation, etc. 3) Aging of insulation due to long-term operation, debris or vibration causing the insulation pads to move between certain revolutions of the rotor, partially blocking the rotor ventilation holes, causing local overheating and aging of the rotor winding insulation, causing the rotor to ground. . 4) Rats and other small animals enter the excitation circuit, the insulated water pipe in the stator water inlet and outlet is casedry and leaking, the excitation circuit is dirty, etc., causing the rotor to ground. 2. The phenomenon of rotor grounding: when the rotor circuit is grounded at one point, no current loop is formed due to grounding at one point, and no current passes through the fault point. The excitation system remains normal and does not affect the. normal operation of the device. Check if the rotor ground signal can be reset. If it can be reset, it is instantly grounded. If it cannot be reset, use a multimeter to measure the voltage from the positive and negative poles of the rotor to ground. As the voltage from one pole to ground drops to zero, the voltage from the other pole to ground rises to full voltage, indicating that a small grounding has occurred. 3. Rotor grounding treatment: 1) Check whether anyone is working in the excitation circuit. If this is caused by a membere staff, this needs to be corrected. 2) Check whether there is obvious damage to each part of the excitation circuit or whether it is grounded due to dirt. If it is grounded due to dirt, it must be purged. 3) Perform a detailed external inspection of the affected circuits and, if necessary, deactivate the rectifier cabinets in turn to determine if this is due to grounding of the DC circuit of the rectifier cabinet. 4) Check whether the ground is in the excitation circuit or the measurement protection circuit. 5) If the rotor is grounded on a stable metal mass at one point and the fault point cannot be identified, in addition to strengthening the monitoring of the operation of the unit, after obtaining authorization to During shipment, the two-point grounding protection of the rotor should be used for tripping and request closing as soon as possible. 6) The rotor workswith an earthing point. If the unit is underexcited or out of phase, the rotor ground can generally be considered to have changed to a two-point ground. The point grounding protection action will trigger. Otherwise, the machine must be stopped immediately. For internal dual water cooling units, if water leakage occurs when the rotor is grounded at one point, the machine must be stopped immediately.
What is the generator display stage? The rotor
Short circuit fault between the rotor windings is a common generator fault. In the event of a slight short circuit between the turns, the unit can only continue to operate, but care should be taken to strengthen monitoring and testing. When the short circuit between the turns is serious, the current of the rotor will increase significantly and the temperature of the rotor will increase significantly. rolls it uprotor will increase, limiting the reactive power of the generator, or cause the unit to vibrate more, or even force it to stop. Therefore, when an inter-turn short circuit fault occurs in the rotor winding, the inter-turn short circuit point must be found by testing and eliminated to restore normal operation of the generator. The generator rotor is grounded at one point and two points. Additionally, the rotor layer will also be grounded and cause a short circuit between the turns. Rotor grounding can be divided into instantaneous grounding, intermittent grounding and permanent grounding. It can also be divided into internal grounding and external grounding, metal grounding and resistive grounding. Personnel were working on the excitation circuit and the rotor was grounded due to accidental contact or other reasons.
Insulationof the rotor slip ring is damaged, the rotor slot insulation is damaged, and the rotor slip ring insulation is damaged. Damage to the sub-slot insulation and end insulation, damage to the rotor cable insulation, etc. can cause grounding. Insulation aging due to long-term operation, debris or vibration causing the insulation pads to move between certain revolutions of the rotor, partially blocking the rotor ventilation holes, causing local overheating and aging of the rotor. insulation of the rotor winding, causing the rotor to be grounded. Rats and other small animals enter the excitation circuit, the insulated water pipe at the water inlet and outlet of the stator is broken and leaking, and the excitation circuit is dirty, causing the excitation to the rotor earth. When the rotor circuit is grounded at one point,no current loop forms due to grounding at one point and no current passes through the fault point. The excitation system remains in a normal state and does not affect the normal operation of the unit. . Check if the rotor ground signal can be reset. If it can be reset, it is instantly grounded. If it cannot be reset, use a multimeter to measure the voltage from the positive and negative poles of the rotor to ground. As the voltage from one pole to ground drops to zero, the voltage from the other pole to ground rises to full voltage, indicating that a small grounding has indeed occurred. How to handle rotor grounding: Check if anyone is working in excitation. If the problem is caused by a staff member, it must be corrected. Check if there is obvious damage to each part of the excitation circuit or if it is grounded due to dirt, it should be purgedé and the circuit concerned must be inspected in detail if necessary, the rectifier. The cabinet should be shut down in turn to determine if this is caused by grounding of the DC circuit in the rectifier cabinet. Check whether the ground is in the excitation circuit or in the measurement protection circuit if the rotor is grounded to a stable metal. grounding at one point and the fault point cannot be identified, in addition to strengthening the monitoring of the unit operation, after obtaining shipment consent, apply two-way grounding protection points on rotor tripping and request shutdown treatment as soon as possible.
That is, the magnetic poles on the rotor are highlighted. (As shown below left)
A generator is a mechanical device that converts other forms of energy into electrical energy. Generators are generally composeds of stators, rotors, end covers, bearings and other components. The rotor is composed of rotor core winding (or magnetic pole, magnetic choke), retaining ring, center ring, slip ring, fan and a rotating shaft.
The shape of generator rotor is divided into hidden pole type and explicit pole type. Hidden pole type: the rotor is cylindrical, thin and long, there are no protruding magnetic poles on the rotor, the speed is high, and the number of magnetic pole pairs is small. It is typically used in turbine generators; Pole type is also called salient pole type: the rotor is large. Most of them are shaped like a round cake, with pairs of magnetic poles and excitation coils visibly protruding from the rotor. They have a low rotational speed and many pairs of magnetic poles. generallyused in hydroelectric generators.