Light is the life of television art. The safety and reliability of the dimming system is a powerful guarantee for using light to shape the objective world. The power of any professional dimming system is very large. A single bulb is 5kW or even 10kW, and a performance can use thousands of bulbs. It can be seen that the total power consumption of a dimming system is amazing. Therefore, the efficiency and heat dissipation of the dimming system is very important, and it is the key to maintaining the reliability of the dimming system for a long time.
The dimming device has gone through four generations: the first generation is a resistive dimmer. The second generation is a transformer type dimming device. The third generation is an electromagnetic amplifier type dimming device. The fourth generation is a thyristor dimming device. The first generation was the least efficient and the fourth generation was the most efficient.
If the efficiency of the dimming system is not high, the power consumed by itself is considerable. Assuming it's 96% efficient (it seems to be a very good number), when it pushes a 6kW load, its power consumption is already:
Also assume that a dimming cabinet has 60 6kW loads, and its total power consumption is as high as:
Therefore, it is important to improve the efficiency of the dimming system. It not only reduces the temperature rise of the dimming cabinet (because the temperature rise and power consumption are directly proportional), but also reduces the power consumption, thus reducing operating costs. Currently, more advanced dimming systems use the latest solid state switches and are highly efficient.
The choke has an efficiency of over 98%, which reduces the large disturbance caused by the sharp rise of current due to non-100% dimming. (The thyristor adjusts the voltage by changing the conduction angle. Its on-time is only about 1μs. This current waveform is actually a sharp pulse at the leading edge.)
However, even with a very efficient dimming system, the performance and design of the cooling system is still important. Even with 98% efficiency, taking the above as an example, its own power consumption is still as high as 7.2kW. To effectively discharge such large power consumption outside the system and keep the internal components of the system working in a reasonable temperature environment, the rational design of the heat dissipation system cannot be ignored.
At present, there are three types of vertical cabinet cooling systems in the world: forced air supply, forced air extraction and intelligent ventilation.
Forced air supply：
This cooling system installs the blower at the bottom of the cabinet, allowing fresh air to enter from the bottom of the cabinet and then accelerate upwards to remove the heat generated by the thyristor.
The advantage of this approach is that it is efficient and can take a lot of tropicals with a small fan. Its disadvantage is that the cold air drawn from below is constantly heated by the power consumption of the thyristor while flowing upwards, so the temperature of the thyristor at the top is much higher than that of the bottom, resulting in the top thyristor. Reliability and longevity.
Forced air extraction：
This system is designed to mount the extractor on top of the cabinet. Fresh air is introduced from the front of each thyristor through a suitable process design, and then the hot air is vented outside the cabinet by suction.
This method is precisely designed (fluid dynamics) and rigorous process control, so that the amount of air in each thyristor from the top to the bottom is approximately the same, so that each thyristor is acceptable. Operating within the temperature range ensures the reliability of each thyristor. However, this design also has the disadvantage that the wind resistance is large, and the power of the exhaust fan needs to be increased, so that the noise is also large.
Since the dimming system is rarely fully loaded under normal operating conditions, the amount of air required can be relatively reduced. According to this theory, the intelligent exhaust is based on the detection of the temperature rise in the vertical cabinet, and then determines the amount of air. In the general operating environment, the fan only needs to run at a low speed, and the noise is relatively reduced, but when the load increases, the fan is accelerated accordingly. In this way, the advantages of forced drafting are retained, and the disadvantages of high noise are also solved.
Finally, it is worth mentioning that, despite the high dimming efficiency and good heat dissipation system, the dimming system is always a very powerful electrical system. High temperatures and the occurrence of arcing and ignition can not be completely avoided. Only on the basis of high efficiency and good heat dissipation, supplemented by the necessary high temperature and fire prevention measures (such as the use of high temperature flame retardant lines), the safe use of the entire dimming system can be guaranteed.