Circuit Breaker BA201If you need to choose the right circuit breaker for your electrical panel, you need to know its characteristics. The most basic characteristic that is oriented when buying this device is the rated current. She is emblazoned on the body of the circuit breaker, written in large numbers and letters.


  • 1 The main characteristics of "machines"
  • 2 Rated current
  • 3 Response time
  • 4 Rated voltage
  • 5 Maximum switching capacity
  • 6 Arc limit class

The main characteristics of "machines"

Key technical characteristics of circuit breakersToday, there are circuit breakers specifications, which differ significantly. If the circuit breaker or “automatic” is of the Soviet type, then the rated current on it was written in its usual form, for example: 16 A. On the Chinese "automata" you can find only the digital designation, in front of which stands a letter. This is also an important feature, which will be discussed later.

Rated current

Before you select the desired circuit breaker, you need to know what the load will be on it. All the devices inside the premises and included in this electrical circuit are called its consumers. It is necessary to calculate such a characteristic as their total power, moreover, the maximum one. Do not forget that the number of devices that can be hung on one circuit is determined not only by the rated current of the circuit breaker, but also by the capabilities of the wiring itself.

It is important to know and such characteristics:

  • cross-section of the wire, which divorced wiring;
  • rated current.

Speaking about the rated current, it is important to pay attention to which current the installation elements are calculated, since for the network they serve not only sockets and switches, but also equal conductors. They must withstand the same current, as the wires, divorced on the room.

Response time

What are the main technical characteristics of machines?In addition to the rated current, there are technical characteristics of “automata” associated with the response time. Indeed, in many cases it is important: expensive equipment should not have time to fail when overvoltage occurs. For this, each “automaton” has its own time-current characteristic. It shows how quickly the circuit protected by the “automaton” switches off, depending on the current flowing through it. To calculate this parameter, the ratio of the actual current to the rated current of the circuit breaker is taken.

Depending on this response characteristic of the circuit breakers, an alphabetic marking is placed on their case. On Chinese samples, this is precisely the capital letter that stands before the rated current. These may be the designations:

  • BUT;
  • AT;
  • WITH;
  • D;
  • TO;
  • Z.

Domestic use of automatic switches implies an excess of rated current by 3–10 times. Such exceedances are considered normal for transients — inrush currents of some devices. Type B is designed for incandescent lamps, their switches or heaters. "Automatic" with this characteristic Will perfectly cope with the staircase lighting service., since they do not come on when starting several lamps. But in the event of a short circuit in any of the cartridges triggering is ensured.

ABB circuit breakerIf there are devices with more serious starting currents in the circuit - refrigerators, climatic equipment, gas discharge lamps or certain types of medical devices, it is best to opt for "Automata" type C.

Even greater starting currents occur when starting three-phase motors - elevator drives. For this equipment three- or four-section automatic switches are used type D. On this type ends the use of "automata" in homes.

Types Z and K are designed for special use. For example, a type Z circuit breaker is too “thin matter”: it has a very low threshold. Such "Automata" are installed in chainsin which precision semiconductor devices sensitive to the slightest voltage drops are included.

But type K circuit breakers work well with inductive loads. Recall that the inductive consumer gives a strong spark, indicating the maximum current, not at the moment of switching on, but at the moment of opening the circuit. This mode will be critical for any other type of circuit breaker, but not for type K.

Rated voltage

Vykatnaya automatic industrialMany will not consider this characteristic especially important, considering that the power grid is only 220 V. However, even in residential buildings there is a lifting equipment - elevators, which have a three-phase motor, designed for a voltage of 380 V.

This voltage is very easy to get in the apartment with a certain accident of the electrical panel. It is enough that one of the phases hit the neutral wire, as in the remaining phases the voltage can jump to 380 V. And not always automatic switches can "track" this overvoltage. And if they are not triggered on time, electrical appliances in apartments can fail.

The operation of "automata" may not occur if their rated voltage is 380 V, and not 220 V. Many residents of houses believe that if you put a circuit breaker with a voltage margin, it will last longer. However, the stock should be chosen by the current, if you only plan to buy powerful devices. Stock should be at the very wiring. Otherwise better to throw another entry into the apartment with its circuit breaker and conduct this circuit with a larger wire and with the earth conductor.

Maximum switching capacity

Automatic OptiMat DThere remains one more technical parameter, the value of which should be explained. This characteristic indicates the current at which there is literally welding of contacts automatic switch, which makes it stop working, turning into a conductor.

Applying such a large current to the circuit breaker is a good chance to start a fire in the room, if only Before this circuit breaker in the circuit is not worth the "automatic" with a higher limit switching ability. Then its operation will save the wiring from overheating and fire insulation.

This characteristic is indicated separately for AC and DC. Its value on the circuit breaker can be seen in the rectangle, which is located below the main characteristics: the type of "automatic" and rated current.

Arc limit class

Modular circuit breakerThere are also characteristics such as the arc limit class. When the circuit is broken, in which the value of the current "rolls over", an arc always occurs. The circuit breakers for this there is a special arc quenching chamber. The arc-limiting class shows how quickly it is not extinguished by the arc that occurs when the circuit breaks in the “automaton”, but that which occurs precisely at the point of short circuit occurring in an external switch, outlet, junction box or electrical instrument.

Thus, having studied in detail the basic electrical parameters of the “automata”, it will not be difficult to choose the optimally suitable option. The above information will also help to significantly increase their lifespan.