How to connect the RCD

    1. Concerning neutral, we say that three-phase voltage is applied in industry. This is due to the fact that it is possible to get the most power( the same three wires) with relatively high efficiency. All engines located in the apartment are a stripped-down, ridiculous, incomplete version of equipment at 380 V. But it is difficult and unwise to pull four electric wires into each room. This saves electrical wiring in the first place. Three-phase circuits do not always have a neutral pin. This term denotes the midpoint of three symmetrical and equivalent windings. Usually the neutral is grounded. But, it is noticed that for the supplier it is not always required. With a symmetrical load from the consumer, the output currents flow away to the phases, where at a particular point in time there is a different polarity. Three phases come( differing by a shift of 120 degrees) and there is no ground( neutral, zero electrical wire).Sometimes a three-phase motor can have only three contacts, and a device with 220 V leads can have 5, and 6, and more due to the presence inside of any contactors, sensors, fuses. So, the RCDs can be made for circuits with insulated neutral - a case when the load is assumed to be symmetrical - or deaf-grounded( the wire digs into the ground on the side of the substation, with variations on the nature of use).Please note that it is important for the energy supplier that his transformer is loaded evenly across the windings, otherwise a component may fail. But what is an isolated neutral. In case of a short circuit to the case of one of the phases, the device will continue to work further. If you now touch the engine with your hand, and the second is to take up the good old cast-iron battery, then a fatal or other negative outcome is likely. Actually, for this purpose the UZO is installed. In order to check the correctness of the equipment connection, OES 7 is used. These rules are approved at the state level, and prescribe the need for builders in new buildings to provide for the presence of an electrical ground wire( and in the good old Soviet ones this is not available).The same is foreseen in the reconstruction of the supply network. The specific type of RCD is based on the termination circuit present. An electric three-phase motor may simply not have an output for grounding. In such a case, it is necessary to ensure security, however, this should already be clear from what has been said.

      Different types of devices

    2. As for the type and frequency of the current, we are talking about 220 V and 50 Hz. This moment is extremely understandable, but we recall that the specified parameters are suitable for an apartment, and in the industry the UZO dominates in three phases. The frequency can be fundamentally different - for example, be 400 Hz - and even features are present. First of all, you need to know that a large part of the equipment deteriorates irreversibly when any of the phases disappears. And the similar moment in household UZO for 220 V is not provided. It is impossible to put such a thing in the amount of three pieces - 1 per wire - to be installed to protect serious equipment. As for the RCD for 380 V circuits, there similar moments should be played in the manufacture. More you need to look at the passport, make sure that the presence of all phases is important for the connected equipment. Finally, RCDs are designed for DC and rectified current. The difference is present in the number and presence of harmonics( relatively small fluctuations in input current and voltage values).We categorically would not recommend using RCDs that are not intended directly for a particular circuit. We can think that the device for the rectified current will also fit perfectly as the load of some battery. To top it off, say that the RCD can be designed to work in different circuits( combined), which should be indicated by marking.


    3. There are UZOs that react to leakage current, and the GOST R 53312 standard speaks about them, calling UZO-D, and there are those that will power off only if a person takes on the current-carrying part. Both options are beneficial in different cases. Please note that various types of RCDs are designed to operate at encountered frequencies and supply voltage amplitudes. The first in everyday life is called differential automata, and in the industry there are versions for 6 and 10 kV( 50 Hz).Found out the topic of differences. And we believe that now it should be clear how to pick up the RCD and automatic. We remind you that the latter are necessarily placed to protect appliances located nearby( & gt; 60 cm) from sinks, bathrooms, and jacuzzis. But electrical equipment of industrial frequency is not put close to sources of moisture at all. The exceptions are water heaters, they must be connected through differential circuit breakers.
    4. The division by the number of poles in Russian is called the number of phases. This has already been said enough, and we hope, readers have already understood that the circuit for connecting an RCD in a single-phase network can be fundamentally different from the industrial versions of 380 V. Just carefully choose a protection device for yourself.
    5. Finally, electrical installations are divided into portable, manual, stationary, and mobile by the nature of their mobility. And UZO for devices differ according to arising requirements. In everyday life, electrical installations are usually stationary.
    The first gradation plunges into the thick of incomprehensible terms. For example, it is proposed to classify the RCD according to the nature of the application of the neutral, the type and frequency of the current, the number of phases, voltage and mobility. Understand:

    Safety Disable Device

The answer about the correct connection of the RCD is in the plane of its internal structure. If we look, for example, the standard GOST R 53312, we will see that the document deals with differential automata. That is, devices that react to the difference between the input and output current of the payload( TV, microwave, washing machine).

But how to distinguish difavtomat from UZO, and is there any difference? The classification proposed by third-party sites and sloppy videos of electricians does not suit, and today they decided to look at state standards. And at the same time we will solve the problem of properly connecting an RCD in the apartment.

Classification of protective cutout devices( RCD)

It is known how to check the RCD: there is a special button on the case. They talked about how to implement this device in the home electrical network. Showed how to calculate the RCD.RCDs are different, briefly analyze their classification.

According to the rules of registration of documents, the term should be given at the beginning of the text in full, and its abbreviation is indicated in brackets. In other cases, this is decided by making the list in the first paragraph of the table of contents or in the text the concept is decoded, and then the abbreviated record is used. We apologize in advance for the absence of such a hard separation. In the course of the text will appear as an abbreviation of RCD, and the term - protective device off.

Already spoke something about this topic in previous reviews:

  • is installing the RCD before or after the machine;
  • where it is impossible to do without differential switches;
  • looks like the correct connection of the RCD on the electrical circuit.

The proper connection of the RCD in the apartment begins with the selection of the device. And often it turns out that the device is already purchased.

It is difficult to say what it is from the point of view of the consumer. We recommend to imagine the situation that a transformer of unknown purpose fell into our hands, and they need to power the soldering iron at 25 V. Obviously, you first have to decipher the marking and understand the purpose of all windings.

GOST 12.4.155

So, according to GOST 12.4.155, it is proposed to classify RCDs in this way:

The second classification can drive the uninitiated person to mind.

Protective device on the mount

So, the second gradation:

  • The first two points of the classification speak of currents and voltages of zero sequence. These terms refer to spectral analysis and the principle of superposition of fields; we will not go into this now. Let's say simpler: we are talking about asymmetrical loads on three-phase circuits, they were mentioned above, and we add that such modes often occur during short circuits of phases. That RCD and react to the facts of the fault. Before buying and connecting inquire about installed equipment. We add that the currents and voltages of the zero sequence arise when one or two phases are interrupted or short-circuited to earth, but not three. In the presence of insulation breakdown between the two phases of the currents and voltages of the zero sequence does not occur. This is required to be considered before installing the RCD in accordance with the existing equipment of the consumer.
  • Further class already sounds not so bad. RCD devices can respond to:
    1. Phase difference( or more precisely, the ratio) between the currents and zero-sequence voltages. How to find these values? The currents and voltages of the forward and reverse sequence are separated by a( usually equal) angle between the phases. The zero sequence currents and voltages for all phases are in the vector diagram in the same direction. On this basis, applying the method of spectral analysis, it is easy to distinguish these components. At a certain kind of asymmetrical loads, zero-sequence reactivity occurs in the circuits. That is, the phase current and voltage do not match. Measuring these parameters, we can judge the presence of various faults in the load.
    2. Relationships between the power supply and zero sequence parameters give an idea of ​​the occurrence of various abnormal situations.

RCD types measure leakage current. These are familiar differential automata. The minimum leakage current is taken from the standards. For example, for a bathroom, the parameter is 30 mA.It is necessary to choose the RCD for the power and the current operation.

Part of the recorders measure the value of the housing voltage relative to the ground. It can be useful to install a UZO of this kind in order to avoid defeat of people.

There should be no operational current( used to power the monitoring and recording devices) in the working electrical circuit. If this happens, the insulation is broken. If such control is required, it is necessary to select the RCD for power and deliver according to the instructions.

Some devices are capable of recording two or more parameters. It is important to combine the connection of the RCD with grounding.

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