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Benefits of Outlet Circuit Breakers for Generator Sets

Nov. 09, 2021

The low-voltage, high-current circuit breaker installed at the outlet of the generator set plays an important role. In the past, due to the huge rated current and short-circuit current of the generator set and the large DC component of the breaking current, it was difficult to manufacture the GCB, and the cost was also very high. Taking into account technical and economic factors, except for the low-oil circuit breaker set at the outlet of the generator set of the small capacity unit (single unit capacity below 200MW), the general large unit (single unit capacity of 200MW and above) mostly adopts the generator-transformer unit connection, and try to use the disconnect Phase closed bus.


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When the high-voltage circuit breaker of the generator set is in normal operation, during the operation of splitting or paralleling, and in the operation process under the accident state, if one-phase or two-phase circuit breaker fails to operate, malfunctions or breaks insulation breakdown due to fracture When the non-full-phase opening and closing state are caused, the safe and stable operation of the power grid will be seriously threatened, and it is very likely that the outlet circuit breaker and isolating switch are not installed.


The advantage of the unit wiring method between the generator set and the transformer set used by units of 200MW and above is that it eliminates the need for GCB and corresponding relay protection at the same time. However, this simplified wiring method makes the stable operation of generator sets, transformers, and systems largely dependent on the operating reliability of the high-voltage circuit breaker on the high-voltage side of the main transformer. The rotor of the generator set is damaged due to the negative sequence current and even caught fire, and the stability of the system is damaged, causing major accidents such as large-scale power outages.


1. Lubricants are not used according to the season. Different brands of lubricants should be used in different seasons. Some generator sets burn bushes because lubricating oil with low viscosity is used in summer, and an oil film cannot be formed on the bearing bush contact surface.


2. The lubricating oil is not clean. If dirty lubricating oil is added to the body, it will block the oil circuit and cause tile burning.


3. Carelessly observe the meter. When the diesel engine is working normally, the oil pressure should be between (0.15~0.25) MPa, and the oil pressure during idling operation should not be less than 0.5 MPa. Many operators seldom pay attention to the oil pressure gauge, so they can't find the hidden troubles in time.


4. Add the engine oil to an inappropriate amount. If the engine oil is too much, the engine oil will easily burn when the engine is running, and carbon deposits will be formed. Generally, the oil level is most suitable between the upper and lower scales of the oil dipstick.


5. Long-term overload causes tile burning. Due to long-term overload operation, the engine temperature is high, the speed is low, the bearing capacity of the bearing increases, and the oil supply of the oil pump is correspondingly reduced. In addition, the viscosity of the oil decreases at high temperatures, which is more likely to cause bush burning.


6. The matching clearance between the shaft and the bush does not meet the standard. If the gap is too small, the oil is not easy to enter, and the oil film layer cannot be formed. If the gap is too large, the engine oil is easy to lose, and the oil film layer is also difficult to form. Therefore, when repairing and assembling, it is necessary to ensure that the bearing gap is within the standard range.


Starlight Power was founded in 1974 and is one of the earliest manufacturers of generators and diesel generator sets in China. If you want get more information, welcome send email to sales@dieselgeneratortech.com, we will pay highly attention on your question.

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