Purpose and installation of two-pole and three-pole circuit breaker

The purpose of the circuit breakers introduced into the circuits of electrical networks concerns protective functions. If a handheld device is used in network overload mode, the likelihood of significant equipment damage increases significantly.

Automatic two-pole and three-pole switches reduce these risks to a minimum, as they provide instantaneous break of the circuits in case of an accident.

We will understand the features of electrical machines, we give tips on choosing, installing and operating such devices.

The content of the article:

  • Circuit breakers
    • Brief description of the bipolar
    • Features of the device triple-pole
  •  Mounting details of switches
    • Connection to network conductors
    • The nuances of the arrangement and fasteners
  • Maintenance during operation
  • Conclusions and useful video on the topic

Circuit breakers

In the practice of using such equipment, there are frequent use of three types of devices: single-pole, two-pole, three-pole.

What is the difference between these three types of machines? Let's try to figure it out.

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Automatic switches different

The community of these electrical appliances is more than diverse. The range does not capture the imagination. However, the high number of protective devices is fully justified, so they have to be used in a wide variety of schemes

A single pole device, in general, does not cause any special questions. If to introduce single phase circuit breaker, the device will work as a normal switch, only in the mode of automatic reaction - that is, without user intervention will break the circuit in case of violation of the specified operating conditions.

Brief description of the bipolar

A similar device, but executed in the form of a bipolar circuit breaker, is somewhat different in functionality.

The circuit design of the bipolar device is made with regard to monitoring and comparing the operating conditions of two independent current lines.

Double pole circuit breaker

The bipolar switch design is designed to protect and block two different lines of the same electrical circuit. Such devices, along with phase locking, are also used to break the neutral conductor circuit.

Bipolar machines are used, as a rule, for implementation in projects of building electrical networks, when control and comparison of working conditions of two sections of a single electrical network is required. In fact, the bipolar configuration of the device is a tandem of a pair of single-pole devices.

However, the two-pole protection and blocking scheme works on the principle of comparing the parameters of each device individually, in real time. If in any of the two control sections the parameters go beyond the boundaries of the installations, both lines are instantly broken.

This important point shows: the replacement of a bipolar automat with a pair of ordinary single-pole devices is impossible in principle. In the event of overload of one of the circuits (or short circuit), only one machine will work.

Double pole circuit breaker

Double-pole version: 1 - plastic case of high quality; 2 - operation is allowed from -25 to + 60ºС; 3 - installation on DIN rail; 4 - the mechanism of the operational platoon; 5 - operation indication; 6 - information panel; 7 - technical designations (+)

But given that the electrical network is unified, electricity will continue to flow through the second device, supplying another section. This situation leads to serious consequences.

Meanwhile, there are two subspecies of bipolar devices:

  • with single pole protection and conventional neutral switching;
  • with protection of both poles and their simultaneous switching.

The first ones are usually used as input automata, due to which the phase and zero conductors are switched. In this case, such a circuit includes the use of an additional PE line - the ground wire.

Double pole automatic with neutral

This device constructively also looks like a two-port network. However, in fact, the device is a single-pole protective circuit breaker that supports the function of blocking (switching) the neutral line of the electrical network

The second ones are used in the circuits of the same network, where they feed on two sections operating under conditions of different current loads.

Features of the device triple-pole

The main purpose of the three-pole circuit breaker is the use of three-phase networks in the circuits. The design features of this type of devices consist in the presence of protective functions at each individual pole.

Tripping a protection at any of the poles leads to the opening of all poles.

Three-phase circuit breaker

Design for work with a three-phase network. Automatic switch for three independent poles with a common lock. As can be seen on the device diagram, the protection is carried out due to the action of bimetallic plates, as well as electromagnetic releasers (+)

Despite the specific purpose of machines of this type, they are quite acceptable to use on single-phase or two-phase lines.

Structurally, a three-pole automaton contains the following elements:

  • control mechanism;
  • contact system;
  • electric arc extinction module;
  • tripping device.

Free contacts are usually mounted inside the cover of the device. The contact system is connected with the crosshead of the main contacts by the kinematic method.

The functional units of the device are mounted inside the case. The lid and body of the machine are made of materials that do not allow electric current (plastic, textolite, etc.).

Inside circuit breaker

The internal contents of the classic three-port designs: 1, 6 - electric arc quenching chamber; 2, 6 - electromagnetic release (core coil); 3,4 - thermal release (bimetal) plate) (+)

The protection mechanism of the three-port network provides instant disconnection, both in the “auto” mode and in the case of manual operation. In this case, if there is an overload in the electrical circuit, the momentary disconnection occurs regardless of the force applied to the control handle.

That is, even if the user keeps the handle in the on state, the machine in the overload mode will still open all the poles.

There is a modification of the three-port network, where one more pole has been added under the zero conductor. In fact, we are talking about a four-pole design in terms of structural details.

Four-pole circuit breaker

Modified device for three phase poles with an additional zero pole. Often, this type of automata is called a quadrupole, which in principle is completely consistent with reality from a constructive point of view.

Functionally, the four-pole automat resembles a bipolar system. The task of the device is the same, only in relation to the three-phase network.

Generalized specifications of automata

Information on the basic parameters of the circuit breakers is indicated on its case. To understand the alphanumeric notation, you must be able to “Read” device labeling.

Widespread in everyday life and industry marked devices that meet the following basic technical characteristics, depending on their design:

Configuration of the machine 1 pole 2 pole 3 pole
DC voltage, V 240 440 600
AC voltage, V 380 380 660
Rated current, A 0,6 – 100 0,6 – 100 0,6 – 100
Shunt release voltage, V 24 – 440 24 – 440 24 – 440
Norm of ambient temperature, ºС -25 / +60 -25 / +60 -25 / +60

Devices are chosen according to certain criteria, including voltage, nominal current, temperature.

Read more about the choice of circuit breakers in the articles:

  1. Choice of circuit breaker: types and characteristics of electrical machines
  2. Selection of an automaton based on load power, cable cross section and current: principles and formulas for calculations

 Mounting details of switches

For all electrical devices of this design, the order of introduction into the electrical circuit is defined.

Installation of circuit breakers

Installation of circuit breakers - at first glance, the procedure is technically simple. However, if we take into account exactly all the existing installation rules, the assembly process of automata can be compared with the work of creating computer software.

The established procedure, in particular, assumes the following actions of installers before bipolar and tripolar switches are installed:

  • the device must comply with the performance under the current scheme;
  • the body of the machine has no deformation and damage;
  • the on / off lever works clearly in manual activation mode.

The base on which the device is supposed to be installed should be checked for evenness of the surface. Mounting on the bases, where, due to the uneven surface after fixing, the body of the machine is subjected to bending stresses, is not allowed.

Connection to network conductors

Connection of copper conductors with a cross section of 16 - 25 mm2, perform through cable lugs (GOST 9688-82). If it is necessary to make the connection with conductors of copper section of 4 - 16 mm2, cable terminals of another type are used (GOST 7386-80).

As applied to aluminum wire connections, end elements are used by analogy with TAM-7, corresponding to the parameters GOST 9581-80.

Cable Lugs for Automata

Tips of the conductors brought on contact clips of automatic machines. Often this moment is ignored, the conductors simply twist and in this state are connected to the device. In fact, this approach is already considered a violation. The exceptions are wires with a cross section of less than 4 mm

Mains conductors, supplying voltage from the power source, are connected to the upper group of fixed contacts of circuit breakers. It is necessary to connect and connect the conductors so that they do not create force on the terminals of the machine.

Tips should be tightened with contact clips tightly, but without the critical efforts that can lead to the breakdown of the thread. Seal the conductors in cable lugs should be given high attention. It is necessary to use insulating tubes, tape as a protective sheath.

The nuances of the arrangement and fasteners

When installation of several pieces of equipment is carried out, it is required to follow the rules for the placement of devices relative to each other. Thus, the distance between closely spaced devices should be kept at least 5 mm.

Installation of circuit breakers

Installation of switches in the group. It looks quite nice and neat. Meanwhile, in this case, the installation process is performed with errors. According to standards, when mounted in a group, the distance between the walls of adjacent devices should be at least 5 mm.

The minimum distances from the metal parts of the switchgear: 30 to 50 mm from the top, 5 to 10 mm from the side, depending on the magnitude of the applied voltage.

If devices are used in the installation that are structurally made in an additional shell, all assembly manipulations with them are carried out with the cover of the shell removed. Installation of the cover is performed taking into account the correct occurrence of the leash of the drive mechanism. Fastening the cover with screws is performed uniformly.

Upon completion of the installation, the machines must be checked for the clarity of the on / off time.

Wiring diagrams and switch connection rules are described in detail in this article.

Maintenance during operation

The normal conditions of action of two-pole and three-pole circuit breakers allow you to allocate time for technical inspection of devices no more than one prevention for three years of work. This fact once again confirms the high quality of performance of almost any automaton.

Maintenance of machines

Maintenance of devices. This procedure involves testing the integrity of devices and the reliability of contact groups. As part of maintenance, the devices and their locations are cleaned. The quality of work of automatic mechanisms is checked.

Meanwhile, according to the instructions, a technical inspection is necessarily performed if the circuit breaker has tripped due to a short circuit current.

For any reason, whether the device is triggered under emergency conditions or scheduled maintenance, a technical inspection of the devices turns off:

  • diagnosing the on / off mechanism in manual mode without load;
  • checking the tightening screws of the main and loose contacts;
  • reliability of fixture of the device to the base;
  • cleaning of dirt and foreign objects;
  • Imitation of shutdown by the method of mechanical action on the sensitive element
  • performance check in working mode.

The practice of using electrical networks notes the handling of devices from different manufacturers, including domestic and foreign.

Most of the operated automatic protection devices are characterized by flawless performance in terms of quality.

Conclusions and useful video on the topic

What are automata and how they differ, you can learn from the following video:

About the criteria for the selection of protective devices:

The reliability of the automatic locking devices is often not determined by the brand, but by the correct selection, taking into account the workload. Also a significant impact on the action of the devices has an accurate calculation of the cross section of the conductors that supply the load from the machine and the calculation of the input cable cross section.

When all the nuances of installation are taken into account, even Chinese devices, which are several times cheaper than the branded ones, work for quite a long period of time without any complaints.

Share with your readers your experience connecting bipolar and tripolar switches. Please leave comments, ask questions on the topic of the article and participate in discussions - the form for feedback is located below.

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