Marking of circuit breakers. Types, characteristics and purpose of circuit breakers

Compared to conventional circuit breakers, circuit breakers are located in switch cabinets and are designed to protect electrical wiring from short circuits and overloads during power surges. The marking of circuit breakers on the case contains their main characteristics. On them you can get a complete picture of the device.

Circuit Breakers: Marking and Symbols

There are many types of machines, for example, the old type - AE20XXX.

For example, for an AE2044 machine, the marking is deciphered as follows: 20 - development, 4 - 63 A, 4 - unipolar with a thermal and electromagnetic release. The devices differ in the characteristic black color of the carbolite body.

The marking scheme of the machines is standardized. Its main goal is to most clearly convey to users the basic parameters of the device.

The marking of circuit breakers is read from top to bottom on the housing.

1. Manufacturer or trademark - Schneider, ABB, IEK, EKF.
2. Series or catalog number (AB200 series S200U, SH200).
3. Time-current characteristic (A, B, C) and nominal in amperes (I _nom. ).
4. Rated voltage.
5. Maximum permissible values ​​of tripping currents at short circuit
6. Current limit class.
7. Manufacturer's article by which you can find this type of machine in the catalog.

The image below shows how ABB and Schneider circuit breakers are labeled.

The opening button is marked or indicated in red. If it is only one and is made push, then the depressed position means that the circuit is closed.

The marking of circuit breakers at major manufacturers contains QR codes, which reflects all the information about the model. Their presence is a kind of quality guarantee.

Environmental impact

1. The temperature range for conventional models ranges from -5 ° C to +40 ° C. To work beyond these limits, special models are available.
2. Allowed the operation of the apparatus at a relative humidity of up to 50% at 40 ° C. With decreasing temperature, the permissible humidity increases (up to 90% at 20 ° C).

Types of machines

Automatic machines are selected depending on the power grid.

1. Single-pole circuit breaker

Devices are used in single-phase networks. The phase is connected to the top terminal, and the load to the bottom. The device is connected to the gap of the phase wire in order to disconnect power from the load in case of emergency.

2. Bipolar machine

Structurally, the device is a block of two single-terminal devices connected by a lever. The lock between the shutdown mechanisms is designed so that the phase shuts off before zero (according to the rules of the EMP).

3. Three-pole circuit breaker

The device serves to simultaneously turn off the power of the three-phase network in the event of an accident. The three-terminal combines 3 single-pole with a setting for simultaneous operation. Electromagnetic and thermal releases are performed separately for each circuit.

Circuit Breaker: Features

Automata can have different time-current characteristics:

a) current dependent;
b) independent of current;
c) two-stage;
d) three-stage.

On the cases of most automatic machines you can see capital letters B, C, D. The marking of circuit breakers B, C, D indicates a characteristic that reflects the dependence of the response time of the machine on the ratio K = I / I _nom .

1. B - thermal protection is activated after 4-5 s when exceeding the nominal value by 3 times, and electromagnetic protection - after 0.015 s. The devices are designed for loads with low starting currents, in particular for lighting.
2. C is the most common characteristic of circuit breakers protecting electrical installations with moderate inrush currents.
3. D - automatic machines for loading with high starting currents.

The peculiarity of the time-current characteristic lies in the fact that with the same ratings of machines of types B, C and D, they will be switched off at different excess currents.

Other types of machines

1. MA - without thermal release. If a current relay is installed in the circuit, it is enough to install a circuit breaker only with protection against short circuit.
2. A - thermal release trips when exceeding I _nom. 1.3 times. In this case, the shutdown time can be 1 hour. If the rating is exceeded by 2 times or more, the current release is triggered after 0.05 s. In case of failure of this protection after 20-30 s, overheating protection is applied. A machine with characteristic A is used to protect the electronics. Devices with characteristic Z are also used here.

Automata selection criteria

1. I _nom. - the excess of which leads to the operation of the overload protection. The rating is selected according to the permissible maximum current of the wiring, and then reduce it by 10-15%, choosing it from the standard series.
2. Tripping current. The switching class of the circuit breaker is selected depending on the type of load. For domestic purposes, the most common characteristic is C.
3. Selectivity is a property of selective disconnection. The machines are selected according to the rated current, so that the devices on the load side are primarily triggered. First of all, protection is disabled in places where short circuits occur or the network is overloaded. The time selectivity is selected so that the response time is longer for the machine, located closer to the power source.
4. Number of poles. A four-pole machine is connected to a three-phase input, and one or two to a single-phase input. Lighting and household appliances operate on single-pole devices. If the house has an electric boiler or a three-phase electric motor, three-pole machines are used for them.

Other options

When a circuit breaker is purchased, the characteristics must be selected in accordance with the operating and connection conditions. Each machine is designed for a certain number of operation cycles. It is not recommended to use it as a load switch. The number of machines is selected as necessary. Be sure to set the introductory, and after it - on the line of lighting, outlets and separately to powerful consumers. Mounting methods may vary by model. Therefore, devices similar to those installed in the cabinet are selected.

Conclusion

Marking of circuit breakers is required to select them according to specific needs. Their characteristics are directly related to the cross-section of the wiring and types of load. In the event of short circuits, the operation of the electromagnetic releases is primarily triggered, and for prolonged overloads, thermal protection is activated.