Herald English » electric shock

To be safe from a short circuit/electric shock

HeraldK — Fri, 26 Aug 2022 06:35:23 +0000

(Source from Reuters/Alamy)There are a resistive leakage current generated when a wire coating is peeled off or water is introduced, and a capacitive leakage current in which a high-frequency current generated in a high-frequency device such as an SMPS reaches a metal product case. As products such as inverter air conditioners and LED lighting fixtures increase, the leakage breaker may be blocked due to such capacitive leakage current.

In a simple circuit diagram, the former is represented as having a resistor inserted between the ground and the power line, and the latter as a capacitor connected between the ground and the power line.

Since capacitive leakage has a difference of 90 degrees between voltage and phase angle, the effective power transmitted due to leakage is zero. Therefore, it may be considered that there is no fire risk due to the capacitive leakage itself. However, if a person additionally contacts a place where capacitive leakage occurs, there may be a risk of electric shock. In the case of IGR short circuit breaker, which was banned from distribution in early 2022, distribution was banned for this reason. In this case, it can be considered that a capacitive leakage source (capacitor) and a human body (resistor) are connected in series between the power line and the ground.

According to the revised KEC regulations in 2021, if the leakage current (resistance leakage current) is less than 1 mA, the insulation resistance can be considered good. There is a rule that the malfunction of the breaker due to the capacitive leakage current can be solved to some extent by introducing the IGR blocking. However, even if an IGR breaker is introduced, it will trip if the resistive leakage current flows above the trip current or the total leakage current exceeds 100mA. In this case, even if an IGR breaker is introduced, the circuit is separated to reduce or change the leakage current of the individual breaker itself to a smaller leakage current.

But what would you do if you had a device that held 0mA? With this technology, M.J.ENC would not only leak electricity, but also stay at 0mA even if the device was immersed or tested in water. This can be extremely safe for electric shock or short circuit.

If a short circuit occurs, problems such as poor condition or poor supply of the device that receives current may occur, and in severe cases, a lot of caution is required because it may shock the user.

It usually occurs when using old electronic devices. When electricity is connected or electric wires are used, it is a dangerous phenomenon that sparks fly from the area, causing a user to electrically shock or explode the device.

The reason why a short circuit is really dangerous is because of secondary damage. There are also injuries caused by a user’s electric shock or an explosion of the device, but it is because a fire can occur due to connected plug-ins.

Fortunately, most of the families we usually live in have short circuit breakers, so the risk of electric shock due to short circuit is greatly reduced unless the short circuit breaker fails, but the situation itself is very dangerous and can occur easily, so care is always needed.

Even if a leakage breaker is installed, the device must be grounded because it may not work properly if the device is in poor ground condition. Considering the electric device grounded to the steel enclosure, if a leakage occurs in the enclosure due to poor insulation, a leakage current is generated through the ground wire, causing the leakage breaker to trip. The leakage does not occur due to sufficient insulation resistance between the iron housing and the ground, but when the voltage is abandoned, a person becomes a path of the leakage current and the leakage current flows and the circuit breaker trips. In this way, the presence or absence of ground makes a difference in whether the breaker operates in advance before the human body is electrocuted or after contact with the human body.

In an ideal state, electric devices having an insulating structure have a structure in which a short circuit is unlikely to occur. For example, SMPS, which is designed with an insulated topology, has the primary and secondary sides separated by a lottery transformer (magnetic coupling). The feedback circuit is also separated by a photo-coupler If this design is reflected, if there are no problems with the insulation interval in the substrate design, consideration of induced voltage, actual insulation performance of insulating components, etc., equipment connected to the secondary side would not feel electricity when touched. In the case of these devices, the secondary voltage is floating.If there is something wrong and the potential is high enough for the human body to feel, the electricity will be felt when the human body comes into contact with the reference ground. In the case of arbitrarily adding a ground wire, this ground is connected to the real ground to make the reference potential 0 V so that no electricity is felt.

It is already a proven product and has developed a receptacle that covers up to 300mA.Of course, larger capacities can be covered, but the company (M.J.ENC) recommends 300mA above per outlet of the device. And it is a product that has two outlet codes on the device so that multiple outlets can be used.

▲MYUNGJANGESD CO.,LTD.

▲ CEO : Min-Ju Kim

▲www.myungjangesd.co.kr

▲ mjesd0603@naver.com

▲ +82-32-575-1601

EJ SONG

ASIA JOURNAL

Landmark event in an electric shock

HeraldK — Fri, 27 May 2022 00:00:19 +0000

The Ministry of Public Administration and Security requested special attention to prevent accidents as the risk of electric shock increases due to water in the summer when it rains frequently due to the rainy season.

In the last three years (’16 to’18), a total of 1,593 people were killed in electric shock, of which 54 died.

In particular, in July, the number of electric shock casualties (14% and 226) was the highest in the year due to humid weather due to frequent heavy rains.

In the case of electric shock accidents, 56% (894 people) were directly contacted by charging units, followed by arcs (flame discharge) 33% (524 people) and short circuits 7% (117 people).

By age group, 24% (381 people), 23% (362 people) in their 50s, and 18% (279 people) in their 30s were counted, and their proportion was high as they were related to jobs such as cables and wires, transformers, and breakers.

According to the analysis of electric shock accidents in daily life such as socket-outlets, switches, and home appliances, 445 casualties were reported, followed by 24% (109) under the age of 10, followed by 17% (75) in their 20s and 15% (66).

Among them, 162 people were electrocuted by electrical outlets, especially 52% (85) of children under the age of 10, which requires special attention from guardians.

Factories and workplaces (35%, 597 people) related to jobs were the most common electric shock casualties by place, followed by residential facilities (20%, 313 people), and 34% (106 people) of electric shock in residential facilities occurred as a joke.

In order to prevent electric shock accidents in residential facilities in summer, it is necessary to regularly check whether the short circuit breaker works properly, and to thoroughly cut off the power when maintaining or repairing electrical facilities.

Touching electrical appliances or outlets with wet hands is at high risk of electric shock, so you must remove moisture and use it dry. To prevent an electric shock, a safety cover (cover) should be put on to prevent playing with an outlet, and multi-socket or electric wires should be used in a way that is not noticeable to children. In order to prevent child electric shock accidents, families with children need special attention from guardians to not play with electricity-related items such as wires and sockets, said the Ministry of Public Administration and Security’s prevention and safety policy officer.

However, a product that can be used safely without worrying about such safety accidents has been developed. This product actually showed that there was no electric shock or electric leakage even when the actual outlet was immersed in water and experimented. Electric shock casualties were the most common (226 people, 14.1%) in July, when frequent heavy rains and humid weather continued. It was followed by August (192, 12.0%), June (168 and 10.5%), May (149, 9.3%), April (134 and 8.4%), and September (130, 8.1%).

Electric shock accidents were often caused by direct contact with the charging unit through which electricity flows. Direct contact with Chungcheon-bu was the most common with 894 people (56.5%) followed by flame discharge with 524 people (32.8%) and short circuits with 117 people (7.3%).

In order to prevent electric shock accidents in residential facilities, it is necessary to regularly check whether the short circuit breaker works properly, and to thoroughly shut off the power supply when maintaining and repairing electrical facilities.