The amount of current in an electrical circuit that is allowed to pass continuously without overheating the wire is called safe current carrying capacity or safe current. If the current flowing through the wire exceeds the safe carrying capacity, it is called a wire overload. Generally, the maximum allowable working temperature of a wire is 65°C. When overloaded, the temperature exceeds this temperature, which will cause the insulation to rapidly age and even burn the circuit. The construction of the community security network is inseparable from the security camera system, and the indispensable thing in the security camera system is the overload protection. What this article brings to you is the overload protection of the PPTC resettable fuse in the security camera system.

The power supply of security cameras will not use one-to-one power supply, which will waste a lot of resources and cost too much. Therefore, the power supply of security cameras generally uses a switching power supply to distribute multiple 12V DC power supply to each camera load; some system power supplies use a adaptor (linear transformer), which is rectified and transformed into 12V DC power through a transformer. Divided into multiple power sources, distributed to the camera load. Whether it is a switching power supply or an AC/DC power supply, it is a multi-channel power supply system of a public power supply, which is a commonly used method at present.

In this kind of power supply system, there will be a fatal problem, that is, when one of the camera loads has a short circuit or an overcurrent problem, the utility power supply will be damaged. This is also a common problem, because the camera itself is composed of multiple The system unit composed of electronic components has different quality, craftsmanship, and product implementation standards of different manufacturers. Now with the improvement of people’s living standards and the diversified application of electronic equipment, the electromagnetic environment of the security camera system has become very complicated. Security systems often induce various stray electromagnetic waves, spike interference, lightning current, unstable voltage, electric spark interference, short-circuit wiring, installation errors, and so on. In these situations, the occurrence of any kind of problem may cause the load of the security equipment to generate a large current or generate high temperature due to heat. The result is to damage the power supply and make the system work abnormally.

There are many ways to solve the above-mentioned problems. The fuse-type fuse element is often used at the earliest, and a fuse-type fuse is installed at the input end of the power supply. If there is a problem in that way, the whole system will not work; later, a fuse-type is installed in each branch. Fuse, when one of the loads or wires has a short circuit, the fuse is blown, just replace it with a blown fuse, and it will not affect the operation of the entire system. However, it is often not so simple to replace the fuse. Not only is it inconvenient to replace the fuse (working at height), but in most cases, the fuse is selected larger than the conventional requirement, and the fuse is often burned only when the camera is seriously damaged. In this case, it is the camera. The equipment has been seriously damaged or scrapped, and the camera will not get better after changing the fuse.

In fact, the application of fusing type fuse here only solves the protection of short circuit and overcurrent, but does not solve the problem of over temperature protection. Therefore, it is now recommended to use PPTC resettable fuse, which can protect the device before it burns out. Protection and over-temperature protection are provided at the same time. It will automatically recover after power failure and does not need to be replaced. When a problem occurs in one circuit, the corresponding self-recovery fuse will become a protection state without affecting the normal operation of other circuits.

Not only a large number of facts also explain this problem, but the application of PPTC resettable fuses as overload protection of security camera systems has also become the best solution commonly used in the security industry.