[Nan Yue Stage Lighting Network] Light is the life of TV 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. Thus, the total power consumption of a dimming system is amazing. Therefore, the efficiency and heat dissipation of the dimming system are very important. It is the key to the long-term operation of the dimming system to maintain its reliability.

    The dimming equipment 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 silicon controlled dimming device. The first generation has the lowest efficiency and the fourth generation has the highest efficiency.

    If the efficiency of the dimming system is not high, the power consumed by itself is considerable. Assuming its efficiency is 96% (it seems to be a very good number), when it wants to drive a 6kW load, its own power consumption is already:

    6×(100%－96%)=0.24kW

    Suppose a dimming cabinet has 60 loads of 6kW. At this time, its total power consumption is as high as:

    0.24×60=14.4kW

    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 is proportional to the power consumption), but also reduces power consumption, thereby reducing operating costs. At present, the more advanced dimming system uses the latest solid-state switches and is highly efficient.

    The choke coil has an efficiency of more than 98%, which reduces the great interference caused by the sharp rise of current due to non-100% dimming. (SCR adjusts the voltage by changing the conduction angle. Its conduction time is only about 1μs. This current waveform is actually a pulse with a steep front edge.)

    However, even for a very efficient dimming system, the performance and design of the cooling system are still very important. Even with 98% efficiency, taking the above example as an example, its own power consumption is still as high as 7.2kW. To effectively drain such a large power consumption out of the system and to keep the internal components of the system working in a reasonable temperature environment, the reasonable design of the heat dissipation system cannot be ignored.

    At present, there are three popular cooling systems for closet cabinets in the world: forced air supply, forced ventilation and intelligent ventilation.

    (1) Forced air supply

    This heat dissipation system is to install the blower at the bottom of the vertical cabinet, so that the fresh air enters from the bottom of the vertical cabinet and then accelerates to blow upward, thereby taking away the heat generated by the SCR.

    The advantage of this approach is high efficiency, and a large amount of tropical heat can be removed with a small fan. Its disadvantage is that the cold air drawn in from below is continuously heated by the power consumption of the thyristor while flowing upward, so the temperature of the thyristor at the top is much higher than that at the bottom, resulting in the thyristor at the top The reliability and life expectancy are reduced.

    (2) Forced ventilation

    The design of this system is to install the exhaust fan on the top of the cabinet. Through proper process design, fresh air enters from the front of each thyristor, and then the hot air is exhausted to the outside of the cabinet through exhaust.

    This method, through precise design (fluid dynamics) and rigorous process control, can achieve roughly the same air intake from top to bottom for each thyristor, so that each thyristor can be acceptable Operate within the temperature range, ensuring the reliability of each SCR. However, this design also has disadvantages, that is, the wind resistance is large, the power of the exhaust fan needs to be increased, and the noise is also large.

    (3) Smart ventilation

    Because under normal operating conditions, the dimming system is rarely fully loaded, so the required air extraction volume can be relatively reduced. Intelligent ventilation is based on this theory. By detecting the temperature rise in the vertical cabinet, and then determining the ventilation volume, the fan only needs to run at low speed in a normal operating environment, and the noise is relatively reduced, but when the load increases, the fan will accelerate accordingly. In this way, the advantages of forced ventilation are retained, and the shortcomings of high noise are also solved.

    Finally, it is worth mentioning that although there is a high dimming efficiency and a good heat dissipation system, the dimming system is always a very powerful electrical system. It is impossible to completely avoid phenomena such as high temperature and arc ignition. Only on the basis of high efficiency and good heat dissipation, supplemented by necessary high temperature prevention and fire prevention measures (such as the use of high temperature flame retardant wires), can the safe use of the entire dimming system be guaranteed.