How to connect a difavtomat: a sequence of correct actions, a wiring diagram in a single-phase and three-phase network

The use of a differential device allows you to replace 2 electrical modules at once - a batch machine and a residual current device, therefore, if you connect the difavtomat correctly, you can simultaneously protect the electrical wiring from fire and a living organism from electric shock current. An electrician is invited to switch and disconnect the equipment, but you can do everything yourself.

Design and features

In the construction of electrical systems, various modules are used to protect them, as well as ensure safe use. One of them is a differential automaton. This is a combined device that combines a circuit breaker and a residual current device (RCD) in one housing.

Its use allows you to simultaneously protect electrical cables and equipment from emergency surges in power consumption of the system and turn off the current supply in the event of a leak. In appearance, it resembles a differential relay (another name for an RCD), but there are a number of differences.

Finding out where the difavtomat is and where the relay is is really not difficult. If we compare the labeling of products, then you can see that there is no designation of the letter characteristics on the RCD releases, that is, when C10 is written on the module, this is a differential device, and if 10A is relay.

In addition, an electromechanical relay is drawn on the diagram of the difavtomat body shown.

The composition of the difavtomat

The design of a protective product can be divided into 2 parts - mechanical and electronic. The first consists of switching-type mechanisms and a contact group designed to connect input and output cables, and the second contains a differential current transformer.

The following can be distinguished main elements of the module construction:

• screw terminals;
• contact groups;
• electromagnetic release;
• thermal release;
• arc chute;
• gas outlet channel;
• on and off lever;
• control chart;
• current transformer;
• adjusting screw.

The switch lever is designed to connect the load to the power line. The thermal release is assembled on a plate obtained by pressing two metals with different thermal conductivity, which, when heated, allows it to bend. An electromagnetic breaker is a coil with a core held by a spring. When a short circuit occurs, a magnetic flux arises in it, the force of which exceeds the force of the spring.

Thus, the combined device, like the packet switch, has 2 releases - electromagnetic and thermal. They disconnect the electrical line in the event of a short circuit current on it, or if the equipment connected to it begins to consume unacceptably high power. This may be due to damage to the cable insulation or technical malfunction.

At the same time, using a differential transformer, the module can monitor the occurrence of a leakage current, when it appears, a mechanism is triggered that stops the current flow to the load side.

Operating principle

The integrated circuit breaker uses a transformer. Its operation is based on the principle of changing the balance of the magnetic flux. The transformer is a toroidal ferromagnet on which 2 windings are wound, actually forming 2 coils.

The phase wire of the electric line is connected to the first, and the zero wire to the second. Passing through the turns in the forward and reverse directions, the current creates a magnetic field in each winding. These streams are equal in magnitude and opposite in direction. As a result, a balanced situation is created, since these fields are mutually annihilated.

If an insulation breakdown occurs in the connected line or a circuit to ground occurs, then the balance of magnetic fluxes is disturbed. A voltage appears in the transformer, which is applied to the control terminals of the relay. It works and breaks the integrity of the power line, de-energizing the section of the circuit connected to it.

The operation of a three-phase difavtomat occurs in a similar way, but when winding a transformer, 4 windings are used, 3 of them are phase and 1 is zero. If there is no leakage current, the total magnetic flux will also be 0. In the event of current losses in at least one of the phase wires, a magnetic field appears, which triggers the relay.

In order for the device to react to a large current value, it is used solenoid (core coil) and thermal release. When a short circuit occurs, the current on the line rises instantly, which causes the solenoid core to be pulled in. Its movement activates the release mechanism that opens the power contacts. With an instantaneous break of the contacts, an arc is formed, for extinguishing which an arc extinguishing chamber is used, consisting of a set of plates. The resulting gases are discharged through the vent.

Thermal protection is triggered due to the property of the bimetallic plate to deform when heated. When excessive energy consumption begins, the plate heats up and after a while bends, breaking the protected circuit.

Device characteristics

Before connecting the differential machine, it is necessary to select it correctly. Since the product combines 2 other devices, it is characterized by the parameters of both modules. The most important ones are:

1. Maximum current. Indicates the highest value that the machine can pass through itself without degrading its characteristics. Its value is selected depending on the power and the connected load. Modules for 16A are usually installed on socket groups, and modules for lighting 10A.
2. Release type. It is designated in Latin letters and is characterized by a time-current characteristic, that is, how many times the current rating should be exceeded.
3. Working voltage. It is possible to connect the differential machine in a single-phase and three-phase network. For a 220 V network, devices with 3 screw terminals are intended, and 380 V - with four.
4. Setpoint current. Determined by the minimum value of the leakage current. In domestic environments, ratings of 10 and 30 mA are used.
5. Differential relay class. Shows which waveform the module is responding to. This can be AC, DC or ripple current with different trip delay times. The choice of the required class is based on the type of load. In private houses and apartments, class A machines are used, for AC lighting fixtures.
6. Trip current. It is characterized by the value at which the device is triggered. The most common are automatic machines designed for 6000 A.
7. The degree of current limitation. There are 3 classes that denote the time when the device load is de-energized in the event of an emergency current value. The fastest is the third grade.
8. Temperature range of use. Usually it is in the range from -5 C to +40 C.
9. Execution type. In the production of difavtomats, 2 types of devices are used - electromechanical and electronic. The fundamental difference between them is that the former can disconnect the neutral wire, while the latter require a power source for their operation, but have smaller dimensions.

Installation and connection

Before you directly start connecting the difavtomat to a single-phase or three-phase network, it is installed in an electrical panel. Editing is not associated with any complex actions and is within the power of even a not very experienced person.

As recommended by an electrician, the device prior to installation it is necessary to carefully check for cracks and chips. Next, you should de-energize the input line. For this, the introductory machine located in front of the meter is usually turned off.

The differential protection module itself is fixed to a DIN rail pre-installed in the shield. This bar has protrusions on the top and bottom sides, and the product to be installed has a latch on the back.

To grip them together, the top mount is put on the rail, and then, with a little effort, the bottom of the device is pressed until it clicks. After that, in the horizontal plane, the machine can be moved to any place along the entire length of the din-rail. Insulation is removed from the required wires - about 10 mm - after which they are inserted into the sockets of the machine and pressed with screw clamps. There is a rule that the input wires start from the top, and those going to the load from the bottom. The color coding of the wire is also maintained: phase ones are brown, neutral - blue, and grounding - green.

As soon as the device is installed in its place, proceed to its connection. In this case, the difference between a single-phase network and a three-phase network lies in the number of current wires: 1 or 3, and the switching principle is the same. There are three types of connection:

• introductory;
• selective;
• with grounding.

Typical switching

The most common option is the connection diagram of the difavtomat as an input device. This arrangement implies its installation immediately in the line after the meter or an introductory separate machine. There is no fundamental difference where to install the device: before or after the input packet switch, there is no.

The connection is as follows: the phase wire coming from the meter is put into the upper terminal device, designated on the case by the Latin letter L, neutral is fixed in the terminal, signed with the letter N. From the bottom contacts of the difavtomat, the neutral wire is connected to the zero block, and the phase wire is connected to the packet switches. Then, from each switch, it is directed towards the load it protects, and a neutral wire with a terminal block is stretched there.

Such a connection protects all wires and equipment from damage, and the human body from leakage current in the event of an accident on any distribution line. But at the same time, the whole house will be de-energized, and this applies to both the outlet group and the lighting.

Selective scheme

Here, both an introductory difavtomat and separate modules for various load lines are used. The beginning of commutation is the same as in the previous method. But before disconnecting the batch machines, the wires are connected to the group combined devices. To do this, the phase conductor is connected to the differential module immediately behind it, and a jumper is already placed from it to the second, and so all the devices pass. The neutral conductor from the zero bus is brought to each machine with its own piece of wire. From the output of the modules, the conductors are connected to the packet switches, and then to the load.

The advantage of this option is the ability of the system to de-energize the part of the circuit where the accident occurred, while the rest will fully work. The selectivity of the circuit implies the use of devices from larger to smaller, that is, the input device must have greater electrical response characteristics than group ones. For example, the module to be installed per group is selected with a leakage current of 30 mA, and the input module is 100 mA.

In the private sector, the electrical cable consists of 3 wires for a single-phase network and 5 for a three-phase network. An additional conductor is ground. In this case, the grounding element is connected to a separate block and from it is directly connected to the load.

As soon as the wiring is completed, use a multimeter to check if there is a short circuit on the lines. If everything is in order, the introductory machine turns on. The performance of the differential modules is checked using the "test" button provided in their design.