Slip Ring, as a key transmission hub between rotating component (hub) and stationary component (cabin) in wind power generating set, acts as an important role in overall safety, stability and efficiency of overall motor with its directly sound operation conditions. Once slip ring is broken down, a series of chain reactions will be generated, causing severe effects on power transmission, control system, operation safety as well as its maintenance costs of the motor.
First, power transmission interruption that can cause its generating capacity loss
Slip Ring acts as transmitting its power generated by the motor from rotating hub side to its tower cylinder side and finally connecting with the public electric power system. If the following problems happened, including ineffective contact of Slip Ring, over-worn of the brush, corrosive conductive ring or even ineffective insulating, the followings will be happened:
- Instable current transmission that can cause voltage fluctuation or momentary power failure;
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If severe, power output will be totally interrupted that cause the fact that the motor will be forcedly to be shut down, which can directly bring about its generating capacity loss;
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In the condition of high load capacity, its contact resistance will be increased that can cause its local overheating and can even cause a fire, threatening its equipment safety.
Second, control signal interruption that can cause abnormal operation of its pitch system.
Modern wind power generating sets depend on precise pitch system to control and adjust its blade angle for the purpose of optimizing its wind-power capturing efficiency and of ensuring its equipment safety. Slip Ring serves the function of transmitting its control order and its power to its pitch system inside the hub. If the channel of the signal of Slip Ring is failure, which will cause the followings:
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Pitch Order cannot be transmitted, causing the fact that the blade cannot be fully feathering or adjusted its angle in time.
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If wind-shift line or emergent shut down, causing the fact that full feathering cannot be safely operated. And, related risks will be increased, including abrupt acceleration, over-speed and structural damage.
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Insynchronous pitch of each and every blade, causing increasing vibration of the unit and unbalanced load. And, key components will be increased its fatigue, including the gear box and main shaft.
Third, abnormal data communication, causing impeding its state supervision and fault diagnosing
Slip Ring acts as sensor-data feedback including the data of the temperature, its vibration, rotate speed and the angle). Once the signal transmission is blocked, the followings will be happened:
- Supervision system cannot gain real-time data of inside hub, causing Black Boxing;
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Ineffective fault pre-warning system, causing the fact that potential problems cannot be found in time and sudden fault risks will be increased;
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The maintenance staff cannot correctly judge fault root causes, causing prolonging its inspection period and reducing its maintenance efficiency.
Fourth, electromagnetic interference and signal crosstalk, causing its control system malfunction.
If ineffective shield or aging insulating of inside Slip Ring, probably causing electromagnetic interference or signal crosstalk. So , the followings will be happened:
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Bit error for its control signal and data packet loss;
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Fault order or false alarm will be accepted by its control system, causing a series of malfunctions including shut-down malfunction and pitch malfunction;
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Increasing logic mess of its control system within long-period operation, affecting overall equipment stability.
Fifth, increasing maintenance costs and safe risks
Generally, the failure of Slip Ring is hardly to be directly found. That failure can be inspected after machine stop. Once failure, the following will be happened:
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Slip Ring will be repaired and even to be returned after machine stop. If shutting down for a long time, its generating capacity loss will be increased.
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Slip Ring will be operated its regular maintenance with its working high above the ground and a series of complex processes, which will increase safe risks for the staff and its maintenance costs.
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If the failure is not be repaired in time, peripheral devices are probably affected including pitch motor, the controller and the cable, causing related secondary damage and even increasing corresponding losses.
Sixth, shortening equipment lifetime, affecting full-life-cycle reliability for the motor
Slip Ring, as a quick-wear part, is easy to be aged especially for itself and related components, if frequent breakdown or long-period of poor operation conditions. For example:
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Conductive powder will be generated by abnormity wear of the brush and conductive ring, polluting inside environment;
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Insulating material will be damaged by related over-heating or arc, reducing overall reliability;
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The component, including bearing and sealing parts, will be increasingly ineffective within unstably long-period of operation, affecting overall lifetime of the motor.
Therefore, in spite of small structure of Slip Ring, its failure will cause a series of severe consequences from its generating efficiency decreasing to severe safety accidences. So, ensuring stable operation of Slip Ring not only represents the key process of improving wind-plant economic benefits but also an important precondition for ensuring its safety, reliability and long-lifetime operation of the motor.
