Circuit breakers marking: current limitation class, rated current and voltage, other designations

The automatic machine is a special contact device designed for switching (switching on / off) an electrical circuit, protecting wires and cables, as well as devices from short circuits. An important criterion for choosing a device is not only the manufacturer, but also the rated voltage and current, as well as the current limitation class of the circuit breaker.

The role of body markings

The device simultaneously performs control and protection functions. Many people understand that when electricity goes out in an apartment or house, you need to check if the machine in the switchboard has turned off. But not everyone is familiar with the characteristics of the devices and the criteria by which they should be selected in order to maintain the performance of the electricity distribution panel.

By design features, machines are:

• Air - installed in industrial facilities where the current reaches a value of thousands of Amperes.
• Cast - used in chains from 16 to 1 thous. Ampere.
• Modular - for residential premises.

The designations on the case indicate the technical characteristics of the device. The marking is applied to the front of the case with a special paint that cannot be erased, so the parameters (symbols, letters, numbers and diagrams) can be seen even when the machine is already connected.

There is no need to remove the device from the shield to read the symbols.

Decoding of marking

When buying a modular security device, it is worth evaluating not only the brand and appearance. The characteristics of the machine play an important role. To do this, you need to understand the information that the labeling of the circuit breakers carries. It includes:

• brand;
• model;
• vendor code;
• current limiting class;
• breaking current;
• time-current characteristic;
• rated current and voltage;
• connection diagram.

Brand, model and current characteristic

The marking begins with the name of the manufacturer, which is applied to the upper part of the case. The most famous are Schneider Electric, ABB, Hager and IEK. They have long been the sales leaders in the market, as they produce high quality products.

Linear series of a switch often means a series of devices in the manufacturer's line, it is performed in numbers and letters. For example, SH200 is a series of devices from ABB, and Acti9 is from Schneider Electric.

According to the model, you can determine the price and technical characteristics. The S200, for example, is rated for short circuits up to 6 kA and is more expensive than the SH200 model (up to 4.5 kA).

There are five types of time-current properties of the circuit breaker, they are applied with the Latin letters B, C, D, K and Z. The first 3 characteristics are widespread. In cases of heavy load and active use of electronics, "K" and "Z" are needed.

The most suitable characteristic for protecting wiring in everyday life is C. Type B and D narrow profile switches are rarely installed, mostly on request.

Rated current and voltage

The number following the letters means the breaker rating - this is the maximum passing current at which the machine does not turn off. It is indicated for t +30 С. For example, a device with a rated current of 15 A will withstand such a load up to 30 C, but if t rises higher, then the device will operate at a lower current.

When the network is overloaded, when the current exceeds the rated one by 15-50%, the thermal release of the device is triggered.

When a short circuit occurs in the network, an overcurrent appears and the machine is triggered in 0.015 s. If the machine is faulty, insulation may start to melt, which is fraught with ignition.

Under the time-current characteristic in Volts, the voltage (AC / DC) with a nominal value is indicated. This indicator determines the type of network in which the machine can be used. For example, 230/400 V means that the voltage of a three-phase network is 400 V, and a single-phase network is 230 V.

Breaking current and current limiting class

The maximum short-circuit current that passes through the device and does not damage it is called the rated breaking current. The value of the limiting currents for modular circuit breakers is 4500 A, 6000 A and 1000 A.

The class of current limitation is applied below. Overcurrents are dangerous by the release of energy, which leads to the melting of the wiring. The breaker trips when the short-circuit current is at its maximum. But to reach this maximum, time must pass. The larger it is, the more damage caused to equipment and wiring.

The current limiter speeds up the disconnection time of the machine, this does not allow the short-circuit current to reach its peak. The current limiting classes are plotted in a square. The larger the number, the sooner the switch will trip:

1. The limit for the first class is greater than 10ms. With this class, there is no marking on the body of the machine.
2. The time of the second class is from 6 ms to 10 ms.
3. The third class works the fastest - 2-6 ms.

Connection and part number

It happens that in production, a circuit for connection is included in the labeling of machines. It consists of a circuit, releases and contacts.

Marking 1 and 2 on single-pole switches means upper and lower contact. The supply wire is connected to 1, the load to 2. On two-pole machines, the numbers 1/3 mean the upper contact, 2/4 - the lower one.

Yet marking N is sometimes found near the circuit, indicating the terminal to which the neutral conductor must be connected. This designation is important in the event that there is no release.

The article will help to find any model of the switch in the catalog of the outlet. This information can be printed on different sides of the instrument.

The labeling of electrical machines will help you choose the most suitable device for your home. However, it is worth considering not only the technical characteristics, but also the operational features of the machine. After all, understanding the operating conditions will not only prevent breakdowns, but also increase the safety of working with electrical appliances in the house.