Analysis and response to the problem of the distribution system of a mine combined building

1 design overview

The complex has four floors, the first and second floors are canteens, the third floor is a multi-purpose hall, and the fourth floor is an activity and office space with a building area of ​​approximately 7,600. The power distribution system is divided into two systems: power and lighting. The branch circuit protection uses C65N series circuit breakers for overcurrent protection. The circuit breaker setting value is 16A. The lighting fixtures use high-efficiency energy-saving light source. The design requires the installation of the lamp power factor cos 0 85, each The number of luminaires installed in the branch circuit is less than 25 盏. The lighting distribution system is designed to meet the specifications.

2 reasons for tripping

In view of the large-area trip and power failure accidents in the protection circuit breaker, the detailed design verification of the sub-region and branch road was carried out on the original lighting distribution system.

From the calculation results, the selection of each branch circuit breaker and the overcurrent setting value are correct, and more than 30% of the margin is reserved. Under normal circumstances, there should be no overload trip and power failure. To this end, from the following aspects of the actual construction of the lighting distribution system parameters and equipment selection analysis:

2 1 Distribution system branch line insulation test

The sampling and insulation test of the trip branch line was carried out with a shaking table. The data showed that the line insulation level was normal, and it was possible to eliminate the tripping power failure caused by the line short circuit fault.

The length is mainly restricted by the conditions of coal seam occurrence, ventilation and safety conditions, and the equipment level of the supporting equipment of the working face.

In 2000, a coal mine in Pingmei simplified the design of two common fully mechanized mining faces in the west wing of the three-level Dingyi mining area into one working face, and arranged the Ding 631060 super-long fully mechanized mining face, which was 2500m long and lengthened. 260m. The super-long working face is less than a normal working face, and the tunneling rate is reduced by 24%; the protection of coal pillars is saved, and the coal mining is 56,000 tons.

2 2 Product qualification review of circuit breakers

After the compliance test of the circuit breaker selected for this project, it is proved that the selected circuit breaker is a genuine C65N series circuit breaker, and it can play normal breaking and protection in other branch circuits of this project, and there should be no quality problems.

2 3 Detection and analysis of each branch circuit current

The actual current value of each branch circuit was measured with a clamp-type ammeter. To ensure the accuracy of the measurement, the current value of each branch circuit was measured three times, and the average value was taken as the actual current value of the branch circuit. For the calculation of the calculation of the current value and the actual current value of each branch circuit, see 1.

It can be seen from 1 that after the second renovation of the comprehensive building, although the number of lamps installed in each branch circuit has increased, the installation capacity has not increased much, and some even reduced, but the measured current is better than the design calculation value. It is about 3 times larger than the setting current value and about 1 32 times higher than the setting current value. According to Ohm's law, the power of the single-phase power circuit is calculated as P = I! U ! The calculation of cos shows that the calculated power factor average value of cos 0 31 under the measured current is much lower than the requirement of the installed lamp power factor cos0 85, which is lower than the design requirement, and the power factor cos0 5 in the incoming lamp manual. It can be seen that the low power factor of installing the luminaire during the second decoration is the root cause of the overcurrent tripping failure of each branch circuit. 1 Design calculation of current value and measured current value comparison Note: The calculated current value in the table is obtained with cos = 0 85.

3 treatment plan determination

According to the above analysis results, it can be seen that due to the low power factor of the installed lamps during the second renovation, the overcurrent of each branch circuit is severe, resulting in the power supply capability of the branch circuit breakers and their corresponding distribution lines of the entire lighting distribution system. To meet the requirements of safe power supply, there are serious safety hazards that must be dealt with in a timely manner. To this end, the following treatment options are proposed.

Option 1: Replace the luminaire. The low-power factor lamps that have been installed have been replaced with high-efficiency lamps with a power factor of cos 0 85, with an investment of about 90,000 yuan.

The advantage of this scheme is that the construction is simple and the construction period is short; the disadvantage is that the investment is too large and not easy to bear compared with the decoration contractor.

Option 2: Adding an in-situ compensation capacitor to increase the power factor of the lamp and reduce the operating current. Parallel a single-phase capacitor at each ballast starting ballast to increase the power factor of the lamp to over 85, with an investment of about 13 million yuan. The advantage of this scheme is that the investment is saved, the construction period is short, and the contractor can bear it; the disadvantage is that the construction is difficult.

Option 3: Transform the distribution system. Replace the distribution breaker and distribution line, and invest about 350,000 yuan. The shortcoming of this scheme is that compared with the decoration contractor, the construction is difficult, the construction period is long, and the investment is too big to bear.

Comprehensive comparison of the above three schemes, combined with the fact that the project has been renovated and the decoration contractor has almost no money to earn, recommend the scheme 2 with short investment period and short construction period as the transformation plan of the project, and get the construction unit and the decoration contractor. Fully affirmed, the problem was solved satisfactorily.

4 Conclusion

For the overcurrent problem of lighting distribution system caused by low power factor lamps, it is feasible and economical to use the single phase shunt capacitor to compensate locally to improve the power factor of the lamp. From the operation situation of this project for more than half a year, the transformation result has achieved the intended purpose, which not only solves the problem of over-current tripping of the protection circuit breaker caused by non-short-circuit fault, but also has obvious energy-saving effect, which has been well received by the construction unit. The scheme recommended in this paper to improve the power factor of the luminaire is also a good reference for the transformation of similar projects.

Earphones is one of our important products , both the in ear headfphones and Earphones With Mic have advantages as follow :

The sound quality of the best in Ear Headphones is amazing.

Military level unite voices more pure.

Great sound experience.

Two voices exports more stereo sound.

These earphones with mic have the mic on the wire and the wired earphones works great.All metal building cavity make a more powerful sound shock.Wide dynamic range;Dual bass sound unit design, a broader range.

Excellent bass response;Connect to all MP3 players and digital audio device.

These Good Quality Earphones have real deep heavy base, excellent high frequency and no distortion. And these earphones are comfortable , completely fit to the shape of the ears.

Earphones

Ear Headphones, Earphones With Mic, Good Quality Earphones

Hebei Baisiwei Import&Export Trade Co., LTD. , https://www.baisiweicable.com