Talk about the common sense of electrician of LED display engineers-1

- Sep 09, 2019-

1. Why must the lighting switch be connected to the fire line?


If the lighting switch is installed on the zero line, although the lamp does not work when it is disconnected, the phase line of the lamp holder is still connected, and people think that the lamp does not work, they will mistakenly think that it is in the state of power failure. In fact, the ground voltage of each point on the lamp is still 220 volts of dangerous voltage. People can get an electric shock if they touch those parts that are actually electrified when the lights go out. So all kinds of lighting switches or single-phase small capacity electrical equipment switches, only connected in series on the fire line, to ensure safety.


2. How to install single-phase three-hole socket correctly?


Generally, single-phase electrical equipment, especially mobile electrical equipment, should use the three-core plug and the matching three-hole socket. Three-hole socket has a special protection zero (ground) socket, in the use of zero protection, someone often only in the socket bottom will be the hole in the wiring pile head and the socket into the zero line directly connected, this is very dangerous. Because in the event that the zero line of the power supply is disconnected, or the fire (phase) line of the power supply, the zero line is connected the opposite way, the metal parts such as the housing will also carry the same voltage as the power supply, which will lead to electric shock.


Therefore, the special grounding jack should be connected with the special protective grounding wire. In the case of zero connection protection, the zero connection line should be specially drawn from the power source, rather than nearby using the zero connection line leading into the socket.


3. Why is it forbidden to bury plastic insulated wires directly in the wall?


(1) plastic insulation wire used for a long time, the plastic will aging crack, insulation level is greatly reduced, when the line short overload or short circuit, it is easier to accelerate the damage of insulation.

(2) once the wall is damp, it will cause large area leakage of electricity, endangering personal safety.

(3) plastic insulation wire directly buried, not conducive to line maintenance and repair.


4. Why use leakage protector?


Leakage protection device, also known as leakage protection switch, is a new type of electrical safety device, its main USES are:


(1) prevent electric shock accidents caused by leakage of electrical equipment and circuit.

(2) prevent single-phase electric shock accident in the process of electricity consumption.

(3) timely cut off single-phase grounding fault in the operation of electrical equipment to prevent electrical fire accidents caused by leakage of electricity.

(4) with the improvement of people's living standard, increase of all kinds of electrical appliances, in the process of electricity, due to the defect, improper use of electrical equipment and safety technical measures against the person get an electric shock and fire accident caused, has brought people's lives and property losses should not have, and the occurrence of leakage protector, to prevent the happenings of all kinds of accidents, to cut off the power supply in time, to protect equipment and personal safety, provides a reliable and effective technical measures.


5. What are the main causes of electric shock accidents?


Statistics show that the main causes of electric shock accidents are as follows:


(1) lack of electrical safety knowledge, fly a kite near the high-voltage line, climb the high-voltage pole to dig the nest; After the low-voltage overhead line is broken, use your hands to pick up the fire line. Night electrified wiring hand touch electrified body; Touch the broken rubber cover knife brake.

(2) in violation of operating rules, live connection lines or electrical equipment without taking necessary safety measures; Touching damaged equipment or wires; Misplacing live equipment; Electrified lighting fixtures; Live repair of power tools; Moving electrical equipment with electricity; Twist a light bulb with a wet hand, etc.

(3) unqualified equipment, insufficient safety distance; The resistance of two-wire ground system is too large; Disqualification of grounding wire or disconnection of grounding wire; Insulation damage leads exposed, etc.

(4) the equipment is out of repair, the circuit is broken by strong wind or the pole is blown down and not repaired in time; The bakelite damage of the plastic cover is not timely changed; Damaged electric motor wire, making the housing live for a long time; Porcelain bottle damage, make phase wire and pull wire short connection, equipment shell electrified.

(5) other accidental causes, such as walking at night and touching live wires that fall to the ground.


6. What rescue measures should be taken in case of electric shock?


In case of electric shock accident, while ensuring the safety of the ambulance, the first thing to do is to make the electric shock victim quickly disengage from the power supply, and then carry out the following emergency repair work.


(1) remove tight clothing that prevents the wearer from breathing.

(2) check the mouth of the electrocutor and clean up the mucus in the mouth. If there is denture, remove it.

(3) rescue immediately and on the spot, such as respiratory arrest, use mouth-to-mouth resuscitation rescue, if the heart has stopped beating or irregular vibration, can be performed artificial chest extruding rescue. There is no excuse for interruption.


If there is a second person on the scene besides the rescuer, the following should be done immediately:


1) provide first aid tools and equipment.

2) dissuade the field staff.

3) maintain adequate lighting and ventilation on site.

4) report to the leader and ask the doctor to come to the rescue.


Experimental research and statistics show that if treatment starts from 1 minute after electric shock, 90% can be saved; If starting from 6 minutes after electric shock rescue, only 10% of the chance of survival; But from after electric shock 12 minutes starts the rescue, saves the possibility extremely. So when someone is electrocuted, use every possible means.


7. What are the measures for safe electricity consumption of the display screen?


With the widespread application of LED display screen, it is very important to correctly grasp the knowledge of safe electricity consumption to ensure the safety of electricity consumption.


(1) do not buy "three none" of the fake products.

(2) there should be a complete and reliable power cord plug when using electricity. The electrical equipment with metal shell should be protected by grounding.

(3) switches and fuses shall not be installed on ground and zero wires. Do not connect the grounding wire to the water and gas pipes.

(4) do not touch live equipment with wet hands, and do not wipe live equipment with wet cloth.

(5) do not connect wires or move live equipment.

(6) when checking and repairing the electrical appliances on the LED large screen, the power must be disconnected first.

(7) when the power cord of an electrical appliance is damaged, it should be replaced immediately or wrapped up with an insulating cloth.

(8) in case of fire of electrical appliances or wires, disconnect the power supply before extinguishing.


8. How to prevent the burning of electrical equipment on the display screen?


The rated voltage of the input line of the commonly used LED display switch power supply is 220 volts, and the normal supply voltage is around 220 volts. If the supply voltage of the power supply line rises momentarily due to lightning strike and other natural disasters, the three-phase unbalanced household line breaks the null line due to disrepair, or the phase voltage rises due to human error wiring and other reasons, the voltage will rise and lead to the overheating of the screen power supply. To prevent the burning of power supply and other electrical appliances, it is necessary to start from the following aspects: first, when the electrical equipment is not used, should try to disconnect the power supply; Second, the transformation of old and out of repair wiring; Three is the installation with over voltage protection leakage switch.


9. What are the basic requirements of leakage protector?


Technically, the following requirements shall be met:


(1) the sensitivity of the shock protection should be correct and reasonable, and the general starting current should be within the range of 15 to 30 ma.


(2) under normal circumstances, the operating time of electric shock protection should not be more than 0.1 second.


(3) the protector shall be equipped with necessary monitoring equipment to prevent the loss of protection when the operating state changes. For voltage type electric shock protector, a zero-wire grounding device shall be installed.


10. How to prevent electrical fire accidents? What happens after a fire?


First of all, when installing electrical equipment, the quality must be guaranteed, and should meet the requirements of fire safety. Qualified electrical equipment should be used, broken switches, lamp holders and damaged wires can not be used, wire joints should be connected according to the provisions of the law firmly connected, and insulation tape wrapped. Tighten screws on the wiring pile head and terminals to prevent poor contact caused by loose wiring. After electrician installs good equipment, do not mean to be able to once and for all, the user is in use process, be like discovery lamp head, socket wiring is loosened (especially mobile electric equipment plug wiring is easy to loosen), contact bad or have overheating phenomenon, want to seek electrician to deal with in time.


Secondly, do not put oil, cotton, wood, wood and other easily dyed items near low-voltage lines and switches, sockets, fuses.


Before electric fire, have a kind of augural, want to cause attention especially, because overheat can burn electric wire above all insulation skin, send out a kind of burning rubber skin, burning plastic bad smell. So, when smelt this odour, should think of the reason that may be electric respect to cause above all, if cannot find other reason, answer to pull off power immediately, till find out the reason, after proper processing, ability closes a switch to send report.


In the event of a fire, no matter whether it is caused by electrical aspects, the first way to quickly cut off the power within the fire range. Because, if the fire is caused by electrical aspects, cut off the power supply, also cut off the fire source; If the fire is not caused by the electrical side, it will also burn out the insulation of the wires. If the power is not cut off, the burned wires will cause a short circuit, causing a wider range of wires to catch fire. After an electrical fire, a cover of earth, sand or a fire extinguisher should be used, but a foam extinguisher should never be used.