LED driving power required for outdoor lighting needs to be considered due to factors such as water resistance, high temperature, lightning strike, etc., so the design is more complicated than the general driving power supply. Then in the design process, the safety problem of the LED driver power supply also needs to be highly valued. Let us talk about the lightning protection performance of the outdoor LED driver power supply.

Lightning is a natural phenomenon of nature, especially in the south with abundant rain. Lightning strikes are divided into indirect mines. Indirect, the losses caused by thunderstorms are enormous. Lei mainly includes direct lightning, conducted lightning and inductive lightning. Because the energy impact caused by direct lig·htning is very large, the destructive power is extremely strong, and the general power supply cannot be tolerated. So let's talk about the effects of conducted lightning and inductive lightning on the drive power.

The surge impact of a lightning strike is a transient wave, a transient disturbance that can be either a surge voltage or a surge current. Transfer to the power line along a power line or other path (conducting lightning) or by an electromagnetic field (inductive lightning). Its waveform characteristics are first rising rapidly and then slowly decreasing. This phenomenon can have a fatal effect on the power supply, because the instantaneous surge shock generated by it far exceeds the electrical stress of the general electronic device, resulting in direct damage to the electronic components.

In the case of a smart power supply, even a transient surge does not damage the device and may interfere with the normal operation of the program, causing an erroneous command, causing the power supply to fail to operate as intended. This also explains why the surge (shock) immunity is a category of electromagnetic compatibility in safety certification.

For outdoor LED lighting drive power, lightning protection is an important indicator of power performance. Therefore, when designing outdoor drive power, you must consider lightning protection. The circuit designed by Mingshida contains a secondary protection circuit. The primary protection circuit consists of fuse FUSE, varistor MOV1, gas discharge tube AR3; secondary protection circuit consists of varistor MOV2, MOV3, gas discharge tube AR1. , AR2; the role of secondary protection is different, the primary protection circuit is mainly responsible for handling differential mode surges, instantaneous absorption of the differential mode surge voltage of the power port. The secondary protection circuit is mainly responsible for handling common mode surges, and the surge absorption through the varistor, the effective absorption of the lightning protection tube and the energy release to the ground, so that the surge impact is greatly reduced after passing through the protection circuit of this stage.

Lightning protection refers to the ability of the power supply to have a surge protection. The LED drive power supply requires a surge (impact) anti-interference test on the safety certification to ensure that the power supply has certain anti-interference ability.

The LED driving power supply exists as a component of the LED lamp. When the LED driving power source and the LED module are respectively placed, the output port of the LED driving power source and the LED module input port must meet the requirements of this standard: can withstand 2kV between the line and the line. 4kV surge between line and ground, Mingshida drive power also has this requirement for the LED power supply port.

At present, LED outdoor driving power supply is still a difficult problem to solve in lightning protection. Of course, the development of electronic technology to the present is not a big challenge from the technical point of view. Just because LED lamps have requirements and limitations on the overall size of the power supply, it is still necessary to design a power supply that meets lightning protection requirements in a limited space. Not so easy. In general, the current GB/T17626.5 only recommends that the product meet the differential mode 2KV, common mode 4KV standard. In fact, this specification is far from meeting the actual requirements, especially for special conditions such as port terminals, factories with large electromechanical equipment in the vicinity or lightning strike-prone areas.

In order to resolve this contradiction, many engineering companies often solve this problem by adding an independent surge suppressor. By adding an independent lightning protection device between the input and the outdoor LED driving power source, the threat of lightning strike to the outdoor LED driving power source is solved, thereby greatly ensuring the reliability of the power supply. It is necessary to point out that for stand-alone lightning protection devices, the reference standard is different from the integrated power supply lightning protection standard, and the reference standard is IEC61643-1 or EN61643-11. Stand-alone lightning arresters are generally composed of multi-stage protection lines. In order to protect the power supply equipment of the latter stage, it must ensure that the residual voltage after multi-stage protection is less than the surge voltage that the back-end power supply can withstand. The smaller the value, the better, generally less than 1.5KV, better design products This value can be lower than 0.8KV.

In fact, in addition to being struck by lightning, the power supply is switched on and off, capacitive, capacitive or large loads, switching of the power system, resonance phenomena associated with switching devices, and various system faults such as system combinations for grounding systems. Both short-circuit and arc faults produce high transient overvoltages (or overcurrents). For example, a high-power drive power supply generates a large surge current into the power supply device at the turn-on instant, especially in the cold start condition, because there are many different capacitors in the power supply, especially for PFC (power factor). Adjust the high-voltage, large-capacity electrolytic capacitor after the line. The voltage is very low before starting the machine. The capacitor is quickly charged in a short time after the mains is turned on. The peak current is much larger than the input current under steady-state conditions.

If it is turned on at the same time when the input voltage is 90 degrees, the inrush current will be larger at this time.

While designing the corresponding lightning protection circuit, it is also necessary to fully consider the stress capability of the component, especially the varistor, discharge tube, rectifier bridge, fuse, EMI filter and other components at the input end of the power supply, and fully consider the waves that may be tolerated. Surge level.

In addition, there are some considerations regarding the proper installation and use of the drive power. If the power supply must be grounded reliably, to ensure that the impact energy has a fixed path to bleed; use a dedicated line to supply power to the outdoor drive power source, avoid large mechanical and electrical equipment around to avoid the surge impact when the electromechanical equipment starts; reasonably control each branch The total load of the lamps or power supply on the road, to avoid the surge shock caused by the load being too large; the reasonable configuration of the knife, the opening or closing must be carried out step by step. These can effectively avoid the surge of operation, so that the LED driver power supply can work more reliably.