How to connect the machine: recommendations for choosing a device and a wiring diagram in the electrical panel

Circuit breakers are used to supply power to the circuit and to automatically de-energize it in the event of a malfunction.

Most often, they are mounted in distribution boards and provide overload protection for the electrical circuit.

To choose and connect the machine correctly, you need to understand the design and technical characteristics of the device.

Design features

The circuit breaker is a rather complex electromechanical device. Some modern models are equipped with electronic control units. But in order to correctly connect the machine in the dashboard, it is enough to understand the design of the classic device. This type of equipment is most often used in everyday life.

An input terminal is located at the top of the device, rigidly connected to a fixed contact. The lower terminal is connected to a bimetallic plate that acts as a thermal disconnector. The machine also includes a solenoid. One of its contacts is connected to a bimetallic plate, and the other to a moving contact.

In the disconnector mechanism, the movable contact is securely fixed by means of a spring, not only in the off, but also in the on state. Thanks to this, fast switching is achieved, and strong heating of the contacts is excluded during an arc or spark discharge, which may appear at the moment of an electrical circuit break. The decoupling mechanism can be triggered in the following situations:

1. When turning on or off the machine manually.
2. When the current in the circuit exceeds the rated value, the bimetallic plate heats up. As a result, it bends and acts on the lever of the release mechanism.
3. When a short circuit occurs in the solenoid, a magnetic flux is induced under the influence of current. The solenoid core retracts and, acting on the moving contact, disconnects the circuit.

All circuit breakers are equipped with an arc chute. It contains copper or steel plates well insulated from each other. The appearance of an arc discharge is accompanied by the formation of a strong magnetic field. It induces an EMF in the plates, which also creates its own field with an opposite charge.

Due to the interaction of the two fields, the arc discharge is drawn into the plates, which divide the arc into parts and cool it.

Also in the chamber there is an opening for the exit of gases formed at the moment of burning of the arc discharge. It is because of the appearance of an electric arc with frequent tripping of the circuit breaker, its contacts can burn out.

Criterias of choice

Before connecting the machine to the wiring, you must choose the right device. Of course, preference should be given to products of well-known brands. Also important is the indicator of the rated current and frequency of the network. However, there are other characteristics that you should pay attention to when choosing a device.

Rated electric current

This is one of the most important parameters of machines, showing the maximum current that can pass through the device for a long time without triggering.

When the electric current exceeds the nominal by 13%, the thermal disconnector turns on.

It must be remembered that the rated electric current must always correspond to the cross-section of the conductors in the protected circuit, and not the load power. To ensure correct operation of the machine and to avoid overheating of the wiring, you need to follow two rules:

1. The cross-section of the conductors is selected in accordance with the expected load in the network.
2. The nominal electric current of the machine is selected depending on the cross-section of the wires.

Thus, the circuit breaker does not allow using all the capabilities of the conductors, but is necessary to limit them. This is intentional so that the wiring does not overheat.

Time-current characteristic

An alphabetic index is used to display the time-current characteristic (VTX). In the marking of all machines, it stands in front of the nominal electric current indicator. To understand this characteristic and its effect on the operation of the circuit breaker, you should study the graph.

It shows the dependence of the response time of the device on the multiplicity of the flowing electric current to the nominal one. The graph clearly shows that with an increase in the multiplicity, the response speed of the device also increases. The fastest are devices of category B, and slow - D. In addition, devices of categories Z and K are produced, but they are not used in everyday life.

It should also be remembered that the schedule has been drawn up for machines operating at ambient temperatures up to +30 ° C. If the temperature rises, the device will operate at a lower current and vice versa. The operation of the machines is seriously affected by the devices located next to them in the dashboard, since they heat up during operation and contribute to an increase in the air temperature.

Experienced electricians use those models of panels in which, after installing all the equipment, there is enough free space.

Choosing the model of the machine, it is necessary to focus on the nature of the load. For the normal operation of outlet networks and luminaires (active load), it is quite enough to use category B devices. However, each apartment has a refrigerator and a washing machine (reactive load), and these units require the installation of category C machines.

Most often, such devices are installed in apartments. But the ideal option is to install category B and C devices. For example, a category B circuit breaker installed in an apartment is connected to the lighting circuit. In this case, a category C device must be in the driveway. If the lamp burns out as a result, the faster device will work. It will only open the lighting network, so there will be no power outages in the entire apartment.

Connection recommendations

The peculiarity of connecting machines in the dashboard is that the conductors must be connected to the necessary contacts. The power cable must be connected to fixed contacts. Since devices of this type can have a different number of poles, it is worth considering the two most commonly used circuitry for connecting machines.

A DIN rail is used for mounting the device. If it is necessary to connect a single-pole circuit breaker, then a phase from an RCD device or an input device is connected to the upper terminal. The lower terminal is connected to the protected electrical circuit.

To correctly connect machines with two poles in an electrical panel, a phase must be connected to the upper left terminal, and a neutral conductor must be installed on the right. From the bottom left contact, the phase wire goes into the electrical circuit, and zero is connected to the right. It should also be remembered that the clamping screws of the terminals must not be overtightened, as the housing of the device could be damaged.

When all the work on connecting the machine is completed, it is necessary to apply voltage to the electrical panel and, using a tester, check the presence of current at the input and output of the device. Before starting to connect the machine, you need to assess your capabilities.

Although this is not the most difficult process, in some situations the work should be entrusted to professionals.