The upper and lower line of the circuit breaker

Update date:2017-12-18 Source:MAXGE

The upper and lower line of the circuit breaker will affect the use of the circuit breaker. On the upper and lower lines. What is the upper and lower?

Aspirant LINE shows the power supply is in the circuit breaker plate with the LINE or at the end of the 1, 3, 5, 7 words (molded case circuit breaker handle "ON" (" us ") above), the LOAD ON the breaker plate with the LOAD or one end of the 2, 4, 6, 8 words (molded case circuit breaker handle "OFF" (" points ") below). The incoming LINE is the one direction, the power cord is loaded, and the LOAD LINE is connected to LINE. For the vast majority of plastic shell type circuit breakers, they can only enter the wire and cannot get into the line.


The reason why you can't get into the line is because:

1.structure for plastic shell type circuit breaker, the aspirant line shows the power cord through the connecting plate - contact - static dynamic contact - soft connection - protection system - connecting plate; The downline is the power line - the connection plate - protection system - soft connection - moving contact - static contact - connecting plate. Next in line, if the breaking short circuit current, arc while most into the arc extinguish chamber, but there will always be part of a charged free gas to the dynamic contact mobile connection part, a phase of free gas charged body contact with adjacent, interphase short circuit can occur. Circuit breaker, on the other hand, even succeeded in breaking short circuit current, but as a connection, protection systems, soft connection, public shaft has been in the power supply voltage under no current flows through the (though), will make the insulation aging, may also produce and creepage and so on.


2.the so-called recovery voltage is the process of breaking the short circuit of the breaker and the voltage between the movement and the contact head. As long as the arc is stretched and driven into the arc chamber, it is cooled, the arc resistance and arc voltage are increased, and the arc can be extinguished when the arc voltage is greater than the recovery voltage. There are two kinds of recovery voltage and transient recovery voltage. The two important parameters of transient recovery voltage are the oscillation frequency f and the over-oscillation coefficient r. The larger the f and r, the higher the voltage between the contact heads and the more difficult it is to extinguish the arc. And oscillating frequency! It has a lot to do with the inductance, capacitance and resistance of the line. The downline is due to a string of components, inductors, capacitors. Resistance is relative to the aspirant line much higher , so its transient recovery voltage is high also many, extinguishing arc is difficult, often caused the breakdown and arc.Some molded case circuit breakers have a lot of margin for using double breakpoints or short circuit breaks, so they can be both in line and in line.


3. it can also cause electric shock hazard after the anti-grafting (downline). Because the average person is accustomed to, it is always considered that the top of the handle (ON) is the power supply, and the lower end (OFF) is the load. Although the circuit breaker is split, if it is not known to the person who thinks the load is not voltage, to touch it, it may be subject to electric shock.

It is necessary to mention the wiring of the electronic residual current action circuit breaker  with overload and short circuit protection. This is because the electronic type residual current circuit breaker tripping coil is installed near the lateral load, the aspirant line trip coil in leakage occurs, it makes the circuit breaker tripped, because of dynamic and static contact open, dynamic contact no voltage; If now to the next in line, leakage, the brake circuit breaker points, from the original load end (because of lower inlet line load into power supply side), to the trip coil and moving contact head office have voltage, if there is a surge phenomena such as fault line voltage, will burn coil, make the function of residual current circuit breaker should be lost.


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