A brief analysis of the causes of frequent tripping of LED display screens

1 The layout of the leakage protector is unreasonable

Due to the particularities of the LED display installation site, such as wiring errors, damaged lines, damage to the leakage protector in the switch box, some electrical appliances not passing through the switch box, etc., as well as the inevitable misoperation and refusal of the leakage protector itself, coupled with the failure to arrange the leakage protector according to the actual power consumption, the total leakage protector frequently trips.

In addition to strengthening management in this situation, it is also necessary to rationally arrange the leakage protectors according to the actual situation from a technical point of view. The leakage protector on the incoming main power supply can be mainly used as the overall protection to prevent electrical fire hazards and electrical short circuits, and also as backup protection for each small leakage protection range. Its rated leakage action current can be selected between 200~500mA, and the rated leakage action time can be selected from 0.2~0.3s. In this way, the influence of surge voltage, surge current and electromagnetic interference on the total leakage protector can be greatly reduced, and the selectivity and reliability of the action of the total leakage protector can be improved. If the secondary leakage protection within each leakage protection range can be placed in an effective protection state, the probability of frequent tripping of the total leakage protector on the construction site can be greatly reduced.

2 There is no secondary or third-level leakage protection within the protection range.

The final leakage protector in the switch box is the main protection for electrical equipment. If the final leakage protector is not installed, damaged, or improperly selected, it may cause the upper-level leakage protector to trip frequently. Since there are many metal conductors and wire joints in the LED display screen, if the wire insulation is not very good, it will lead to frequent leakage; some also add some sockets, and often do not install leakage protectors, often causing leakage. Only by forming an effective second-level or third-level leakage protection mode within each protection range can the frequent tripping of the leakage protector be effectively reduced.

3 The leakage protector itself has certain limitations

(1) Current leakage protectors, whether electromagnetic or electronic, use magnetic induction voltage transformers to pick up the leakage current in the main circuit of electrical equipment. It is impossible to arrange the three-phase or three-phase four-wire completely evenly in the magnetic ring. The three-phase electrical load of the LED display cannot be completely balanced. Under large current or high overvoltage, a certain electromotive force will be induced in the magnetic ring with high magnetic permeability. When this electromotive force reaches a certain level, it will cause the leakage protector to trip. Since the leakage protector with a larger rated current uses a relatively larger magnetic ring, the leakage magnetic flux generated is also relatively large, and the leakage current has to overcome the magnetizing force of the magnetic ring itself, resulting in the actual use of the leakage protector with a larger rated current, lower sensitivity, and greater rejection rate.

(2) The leakage protector has an uncertain operating area between the rated leakage operating current and the rated leakage non-operating current. When the leakage current of the leakage protector fluctuates in this area, it may cause the leakage protector to trip irregularly.

4 Unreasonable selection of leakage protector

(1) The rated leakage action current used in the switch box exceeds 30mA or is a leakage protector that is more than twice the rated current of the electrical equipment, or a leakage protector with a time delay type is selected. Due to the increase in the rated leakage action current or the decrease in protection sensitivity, when a leakage fault occurs, the final leakage protector does not operate, and the upper-level leakage protector may operate.

(2) The starting current when powering up the LED display is often relatively large, and this large current may cause the leakage protector to trip. Therefore, the display box should be powered on in batches as much as possible. In addition, an electromagnetic leakage protector that is less sensitive to surge overvoltage and overcurrent should generally be selected; or an electronic leakage protector that is 1.5 to 2 times larger than the rated current should be selected. However, as the final leakage protection, the rated leakage action current should not be greater than 30mA.

In short, frequent tripping of leakage protectors is the result of a combination of various factors. The most important thing is to arrange the leakage protectors reasonably, narrow the protection scope of the second or third-level leakage protectors, and correctly select the leakage protectors and wiring so that the second- or third-level leakage protectors in each range are in an effective protection state. On the other hand, it is to strengthen electricity management and improve the quality of electricity users through training, and to eliminate non-electrician wiring. This can not only improve the safety of electricity, but also reduce the frequent tripping of leakage protectors and create better power supply conditions for the normal work of LED displays.