- How much power?
Generally speaking, the system type of performance system is nothing more than a computer moving head light, stage matrix, wireless microphone receiver, music player, mixer, peripherals, digital processor, amplifier, speakers and so on. But the size of the system can vary far and wide; a very small system may have only a few devices, while a large PA system may contain hundreds of devices. The size of the system allows for most of the total power to be realized, and there must be a clear method of calculation.
The method is actually quite simple, the first step is to check the power rating of each device through the product manual of the device, and in the second step, all the devices are rated to get the total power. But here in order to solve a problem, the passive speakers are driven by power amplifiers, the power amplifiers and speaker power supplies are not double-counted, otherwise the result will be much larger than the actual.
So the question arises! Should I calculate the power according to the power amplifier or according to the speaker power? Theoretically it should be calculated according to the power of the power amplifier, because the loudspeaker is the power amplifier load and the power amplifier is the access to the grid device. However, in practice, system designers usually choose twice the power of the power amplifier, i.e. twice the power rating of the loudspeaker, or even several times the power amplifier, making the power calculated from the power of the power amplifier more practical than the actual power In practice, it is recommended to calculate the power rating based on the loudspeaker to get a more practical, safer and more conservative power value. Making a simple excel sheet can help you to calculate it quickly.
2. Do I want to use multi-wire cables to ensure safety?
On the basis of a clear and well-defined system capacity, we can answer the question - do I want to use thicker cables? There are old old gods on the internet who have learned from their experiences with these questions, my advice is to learn from experience while getting to the truth. According to Ohm's law, we know that I = P / U. Given a power supply and voltage, we can calculate the current of a circuit. The power of the two systems shown above, for example, 220V supply voltage to calculate the total current.
For 8 LA110 and supporting performance system: I = P / U ≈ 11000W / 220V = 50A
For 8 LA212 and supporting performance systems: I = P / U ≈ 22000W / 220V ≈ 100A
Knowing the current that the circuit may reach, we will select the appropriate wire gauge product according to the cable current indicator provided by the cable manufacturer. The figure below shows the small series that labels are used to provide cable parameters. What you buy cable manufacturer does not provide these parameters, the amount, then you still pretend to hesitate, and then decisively change the place of purchase.
3. Single-phase motorized three-phase electric power
Single-phase electric power or three-phase electric power? This in itself is the wrong question, and the reality is that many issues are clearly more than just good or bad. Change the question, should my system be single phase power or three phase power? This depends on the size of the system and the total power to decide.
Small indoor conference sound reinforcement system, such as the use of two CM15 as the main sound, two CM15 return, the total system power is less than 2300W; then it is more suitable for single-phase power supply, it is not difficult to calculate the current of the circuit is about 10A, as shown in Figure 3, the product parameter table can be used 3x1.5mm ² (copper cable, in the air, the same as the following) cable products. The system is recommended to use single-phase power supply, power connection is convenient, and such a small room may only be able to use single-phase power.
