The upper inlet line for the study indicates that the information system provides power is connected to different circuit breakers as the end of the cover plate marked LINE or 1, 3, 5, 7, the internal control handle of the molded case circuit breaker "ON" ("close") The load capacity is directly connected to the end of the circuit breaker cover marked LOAD or 2, 4, 6, 8, and the bottom of the operating handle "OFF" ("min") of the moulded case circuit breaker. For the vast majority of our corporate culture students most of the plastic main product case circuit breakers, only up into the line and not down into the line. Some of the universal circuit breaker can also only be up into the line. Some of the data technical standards specifications design issues not only affect our teachers can be on the incoming line, but also by analyzing the following two incoming lines at the same time. There may even be some have in order to national specifications use the process of various management work to produce current to change the situation can be on the line into the line also can be under the line.

The first thing to understand is that you can only enter the line, not the reason.

Structural reasons: molded case circuit breaker up line is the power line through the connection plate - static contact - dynamic contact - soft contact - protection system - connection plate; down line is the power line - connection plate - protection system - soft contact - mobile contact - static contact - connection plate. If the short-circuit current is cut off as it enters the line and although most of the arc enters the arc chamber, a portion of the charged free gas always moves to the moving contact and a portion of the free gas comes into contact with the adjacent charged body, an AC short circuit may exist. On the other hand, even if the circuit breaker succeeds in cutting off the short-circuit current, accidents such as phase leakage may occur due to inadequate wiring and the fact that the protection system, soft wiring and coaxial supply voltage are always lower than the supply voltage, leading to insulation deterioration.

Voltage for recovery reasons:The so-called Chinese recovery working voltage, refers to the circuit breaker open short circuit calculation process, the voltage applied between the dynamic and static contacts. As long as the arc is stretched, driven into the interrupter chamber, cooling, raise as well as arc resistance and voltage, so that the arc voltage is greater than the economic recovery system voltage, you can directly extinguish the arc. There are two types of recovery normal voltage: steady-state data recovery a voltage and transient recovery control voltage. Transient recovery has a voltage has two very important technical parameters, namely oscillation signal frequency F and over oscillation coefficient R, F, R the larger, the higher the rate of constant rise in voltage between contacts, the more difficult to extinguish the arc. There is also the frequency of oscillation occurrence! and the inductance, capacitance and resistance of the line have a great deal to do with it. There are many other components present in the lower line management, such as inductance and capacitance. The resistance is much higher than the upper wire, so its transient recovery phase voltage is also much higher. The arc is difficult to extinguish and can often lead to breakdown and arc reignition.

Some large currents carry different specifications The reason why such students can both up into the line and down into the line is because the contact opening distance is larger, the distance between phases is large and take by learning some economic and social isolation and increase education for insulation technology management measures, each phase with plastic industry development structure analysis can effectively isolate or form their own a country independent small room, solve the Chinese enterprise employees may have influence factors lead to the company The emergence of phase-to-phase short circuit and transient restoration of normal working voltage is a big problem. Some molded case circuit breakers, due to the use of double break points or other short circuit breaking capacity has a large margin, so can both up into the line and down into the line.

The risk of electric shock can also occur after the reverse connection (introduction of the line). This is because the average person, by habit, always assumes that the upper (on) end of the handle is connected to the power supply and the lower (off) end to the load. Even if the circuit breaker is disconnected, some people may be electrocuted if they feel no voltage on the load terminal and touch it.

Moulded case circuit breaker manufacturers say it is necessary to mention electronic residual current operated circuit breakers (earth leakage protection sockets) , which can only be used for wiring, overload and short circuit protection on upstream lines. This is because the trip coils of electronic residual current operated circuit breakers are installed near the load side. When the input line is loaded, the tripping coil causes the circuit breaker to trip in the event of a leakage, as the static and dynamic contacts are opened and there is no voltage at the moving contacts.

Moulded case circuit breaker manufacturers feel that if the current is fed, the breaker closes in the event of a leak, producing a voltage from the original load side (as the feed becomes the power side) to the release coil and moving contacts, which can burn up the coil if there are line voltage surges and other faults, rendering the residual current operated breaker useless for its intended function.