Main Power Transformer Solution for Coal Mine

Most of the design adopts scheme one, which pays too much attention to 100% backup in case of failure and neglects the economy.

From the above analysis and calculation, for large mines and large open-pit mines, due to the large installed capacity of power transformers, the basic electricity bill is a huge figure and has to be considered. The probability of failure of the power transformer is very small. can satisfy.

According to the above analysis, the second option (that is, two power transformers working at the same time) is the most economical regardless of whether it is a mine or an open-pit mine.

The only flaw is that when one fails, the other cannot guarantee all the loads of the mine. Although it meets the specifications, it affects production and life for the continuity of production.

The solution can be to add an auxiliary power transformer to the two power transformers.

The power transformer capacity is selected from 20% to 40% of the mine load, and a 10KV bus is added when it is normal. When the bus is disconnected in the event of a failure, the self-provided diesel engine generates electricity to meet the electricity consumption of coal mines.

This will not affect production too much, and will not increase the basic electricity bill. Although there is an initial equipment fee, it is much smaller than the basic electricity fee paid. The connection method of the power transformer is shown in the following figure.

In the above figure, B1 and B2 are normal power transformers, B1 and B2 power transformers are coal mine normal load 80 ℅, B3 is auxiliary power transformer, coal mine normal load 20 ℅, when the power transformer is normal, B1 and B2 power transformers operate simultaneously, and B3 is disconnected.

When one fails, the other can ensure the normal operation of the mine’s first and second load or the open-pit drainage pump.

Once the fault is difficult to repair, a B3 power transformer can be used when normal production and work are affected by a power transformer. After the B3 power transformer is put into operation, the coal mine load is guaranteed to be 100 ℅, and the middle bus bar only has a low-level load on the grounding surface.

The above is the author’s suggestion and needs to be studied. The author found that the power transformer accident rate is not high through many surveys of electricity users. Since the power transformer accident rate is not high, it is not necessary to prepare a backup auxiliary power transformer for diesel power generation. Save costs as much as possible on the basis.

Therefore, in the future design, the comparison of schemes should not only compare the basic investment, but also compare the operating costs, comprehensively compare and grasp the specifications, and optimize the design.

Of course, if the local power supply department preferentially uses electricity or reduces or exempts the basic electricity charge for hot standby, the above scheme may not be considered. In short, the design depends on the specific situation.

For example, the coal mine power source is different from the superior power source, and the fees may be different.

1. The coal mine power source is taken from the superior power source in different busbar sections of the same substation. What you are facing is a contract unit, and the cost may be the basic fee for operating the power transformer. If so, the above option is better.

2. The coal mine’s power supply is taken from two different power sources at the upper level, so you have to sign a power supply agreement with the two, and if you pay the fee, you have to pay the basic fee for the two respective power transformers.

If this is the case, the second option above is more economical. In short, depending on the agreement of the power supply department, comprehensive consideration will be made to reduce the production cost on the basis of meeting the regulations.