Three-pole circuit breaker: overview, views, specifications and reviews

Automatic circuit breakers are designed to disconnect electrical networks when operating currents and short circuits are exceeded. They protect the electrical wiring and the consumers connected to it from overloads and contain from one to four poles. A three-pole circuit breaker is designed to protect a three-phase circuit or simultaneously three single -phase wiring . If an accident occurs on one of the lines, three poles are disconnected at once.

The device solves such problems:

• Protection of the network section;
• Prevention of breakdown of a chain segment;
• With the correct choice of warning unauthorized outages.

Characteristics

The main characteristics of automata are the rated breaking capacity and the cutoff speed. They operate from two shutdown mechanisms: electromagnetic and thermal. The first opens the circuit with a short circuit, and the second - from the action of a continuous load exceeding the nominal. The machine can be used as a switch via the control key.

Rated breaking capacity

The characteristic shows the value of the maximum permissible short-circuit current, at which the switch is able to disconnect the wiring with the devices connected to it at least once. It is indicated on the body of the machine and has the following meanings:

• 4.5 kA - for protection against short-circuit power lines of private housing, where the resistance of the line from the substation to the loads does not exceed 0.05 Ohm;
• 6 kA - protect the residential sector and public places where the resistance of the line is not lower than 0.04 Ohm;
• 10 kA - is used to prevent damage to power lines near the substation.

For household circuits it is recommended to apply models of modification of 6 kA.

Time-current characteristics

In case of uneven power consumption caused by changing the load and switching on or off circuit devices, false alarms can occur due to excess of rated currents. To reduce the probability of their operation, automatic machines with specified time-current characteristics (BTX) are used. The parameter shows the cut-off time at a certain ratio of the current to the nominal value. BTX are the following.

1. B - the electromagnetic release trips after 0.015 sec with a three-fold increase in current in relation to the nominal.
2. C is the most common characteristic when the protection is triggered when the rating is increased by 5 times. Automatic machines are suitable for lighting and household appliances with moderate starting currents.
3. D - automatic machines are designed for large starting currents, for example, when the electric boiler, electric motors and other three-phase devices are switched on. They are used mainly in industry.

Overview of circuit breakers

The machine is connected between the power source and the wiring, which should be protected. The three-pole circuit breaker consists of three contact pairs, where each is connected in series with the thermal and electromagnetic releases. The machine turns off only the phases without breaking the neutral that does not connect to it. If there is a need to disconnect the neutral wire, four-pole models are used. Usually they are used on the main inputs.

Apartments and private houses use Class C automatic machines for moderate loads. The current strength is selected according to the power of the connected devices, where the threshold value is twice the nominal value in order to avoid false alarms.

The products of IEK, EKF, DEK, INTES and "Kontaktor" are widely distributed. Domestic products have sufficient reliability and reasonable prices. Widely used machines for 16 A and 25 A. Imported are more expensive, but well-known companies produce high-quality and reliable models. On the switch, the automatic three - pole price of well-known companies may be very different, but it is quite consistent with quality.

The protective device with a three-phase current is used for entering the house and for feeding professional machines with a voltage of 380 V, for example, an automatic triple-pole 100A switch.

This power should correspond to the counter, if it is after the switch. Usually it is not more than 63 A. A more powerful three-pole circuit breaker is used in industry.

From the feedback and advice of experienced electricians, it follows that machines with overvalued denominations must in no case be used. This could lead to fire or equipment failure.

A four-wire wire with three phases and a working zero is fed to the houses. They rarely use equipment designed for 380 V. The phases in the switchboard are divided. This produces 3 separate lines with a voltage of 220 V.

The advantage of multi-pole machines is the ability to control several lines simultaneously. By setting the automatic three-pole circuit-breaker 25A to three devices of appropriate power, you can monitor each individual line. In the event of a short circuit, one of them immediately turns off everything. Normally, single-phase circuit breakers are installed on each line. When one of them leaves the system, three-phase operation will work, which increases the reliability of the system.

Automatic machines of series VA

Domestic automata are produced in series AE and VA. The first type is obsolete, and it is rarely used. It has low strength of the case, no connection to the DIN-rail. For household applications VA products are better suited for currents up to 63 A, characteristics B, C, D and breaking capacity 4.5 kA.

The domestic three-pole automatic VA switch fully meets modern requirements, while at the same time the price is much lower than imported models.

If you believe in numerous reviews, import models at such high prices should be ideal. But they give misfires, although less often domestic models.

Conclusion

The three-pole circuit breaker is an important part of the home electrical system. When choosing expensive models, one should take into account that all other equipment should be of the same level: wiring, switches and sockets, junction boxes, lighting devices.

The main characteristics of automatic machines are always on the case from the front side. They are selected taking into account the section of the wire and the value of the connected load.