RCD connection to single-phase mains with earth: Right + Milestones

Electrical energy is used in the residential and business sector over the place and active. This is one of the main energy resource, the use of which, however, is not safe. In order to ensure the safety of using different methods of protection.

In particular, the connection of the RCD to the single-phase mains with earth to prevent human electric shock, equipment failures, electrical fires. But the device was able to perform these tasks, you must choose the right protective device and intelligently implement it into the power grid.

We address these issues and is dedicated to our article. We will tell you what options are important to consider when selecting an RCD, denoted by the machine installation requirements, as well as describe the procedure works on devices to connect to a single-phase network.

What safeguards ensure the RCD?

Of course, the introduction of protective devices in the power supply system is accompanied by certain rules. Consider those with respect to the installation RCD.

The security module of a series of such devices is designed as a universal device, so most models are designed to protect against a variety of negative developments in the process of use of electric networks.

RCD operates in three areas of protection:

• prevent electric shock;
• breakdown of circuits with consequent leakage current on the apparatus casing;
• short-circuiting the wiring.

It is noteworthy that all three directions protection operate most efficiently provided by connecting the device with the grounding scheme.

In fact, does not exclude (and often used) is also a scheme without the participation "of the earth." However, in this embodiment, the measurable efficiency decreases significantly.

RCD devices are considered a compulsory component of electric distribution boards for any purpose - permanently fixed, temporary action, portable.

often they embedded in the socket structure or forks, which is performed by connecting the tool and household electric appliances operated under wet, dusty places.

Selection device considering design parameters

The process of designing electrical specialized design organizations should provide quite a challenge selecting appropriate RCD from the range of electrical equipment market.

This problem is really complicated. The modern market of electrical appliances, including the RCD range of different kind. This is the result of the lack of strict quality control on the part of government agencies.

On the market there are plenty of different devices made by a large number of manufacturers, many of which do not always adhere to the current regulations.

Potential owners of the RCD have no choice, how to take the information that the device manufacturer provides. Supplement guarantees a certificate of conformity and fire safety.

The absence of such documents on the goods sold - is a direct ban on the installation and operation, in accordance with current standards.

Selection RCD always accompanied by taking into account the working parameters and operational characteristics, which is largely determined by the quality and reliability of the device.

It is necessary to take into account the nominal figures:

• voltage;
• current;
• differential current cutoff.

These key characteristics must meet the technical parameters of the projected electrical circuit or operated.

Quality and reliability of RCD activities is determined by some indicators, the overall physical meaning of which is often little understood.

These parameters primarily are rated conditional short-circuit current and the nominal current consisting / breaking capacity.

Very rarely RCD manufacturers stated in the document on the instruments all marked characteristics. It is therefore necessary to assess properly all the advantages and disadvantages of selected devices.

From the standpoint of technical design, the RCD traditionally characterize the switching device, whose action is determined by the standby mode. The device has features that help to visually determine the quality of work.

But there is a single principle on which these devices operate the same way. Device included in the operating current of the circuit and if the leakage current occurs with a certain value greater than the preset value, the RCD simply opens the power circuit.

How correctly performed opening? To evaluate the performance of the device circuit switching capacity, service life, and other relevant parameters may only method of specialized tests.

Rules for connecting the device

There are standards with which determined the normal conditions for the installation and subsequent operation of RCDs. These standards are fixed, in particular documents GOST P 51326.1-99 and 51327.1-99.

Therefore, the following criteria should be followed, putting into practice the RCD:

• optimum ambient temperature range -5 to + 40 ° C;
• the relative humidity not higher than 50% at + 40 ° C and not higher than 90% at + 20 ° C;
• boundary value of the altitude of 2000 m;
• lack of strong magnetic fields in the immediate vicinity of the unit.

As pointed out by GOST R 50571.3-94, to connect circuits in buildings important and necessary condition for normal operation of the RCD in the electrical part of the building seen in the absence of its area of ​​action of any connection with the neutral conductor grounded electrical elements and "earthy" protective PE conductor.

For earthing system TN-C-S, in electrical switchboards, at points where the divided PEN-conductor, necessary to provide separate clamps or tires for zero displacement and zero protective N PE conductor.

Given that the RCD device responds to the "earthy" leakage as a zero, and the phase conductors on the lines, as a rule, should be placed Automatic circuit breakers.

The introduction of circuit breakers to quickly identify the faulty circuit portion by alternately turn off individual lines.

Due excluded dismounting machines "ASU" when it detects a defective portion, the leak portion including the zero conductor.

GOST 50571.9-94 contains specific instructions to perform actions directed to protect zero displacement and protective earth conductor.

Carrying out the work of professional services

Theoretically and practically, too, with the participation of experts, set the RCD includes a number of measures for the definition of the threshold device.

There are established rules - a kind of instruction, where there is a whole sequence of actions in such cases.

Progress:

1. First of all, the device is disconnected from the load circuit and the phase to zero, which is used for the circuit breaker.
2. Further, the connection scheme used for RCD devices and adjusting elements (potentiometer).
3. By changing the resistance of the potentiometer achieve actuation device and fixed current readings on the meter.

The noted value of the measuring device at the time of operation - a differential current RCD. Observed current reading should be within the established range.

If the condition is not met, the installation of the protective device in the chain is prohibited. You need to pick up another instance of the appropriate parameters.

When connecting the protective device RCD type grounding, also assumed rules holding works aimed to leakage current measurement device within the boundaries of the protection zones.

Usually such events are required for the mounting of electromechanical devices:

1. Through automatic protection device is connected to the load.
2. According to the test circuit is connected to the instrument measuring circuit consisting of resistances and store ammeter.
3. By varying the resistance box, achieve actuation device and record the ammeter.
4. The leakage current is calculated by the formula: Iy = I - Ia, where I - the shut-off circuit current Ia - ammeter.

The resulting value Iy should not exceed the nominal value of the differential current RCD more than one-third.

If the excess is recorded, it is a clear sign that within the boundaries of the protected area of ​​the device is defective portion. For such cases, PES regulations require execution of necessary actions aimed at eliminating leakage current.

Briefing on the case of home installation

The introduction of the RCD in the electrical network for domestic use, subject to adjustment under the voltage is carried out in compliance with certain requirements.

A list of the mandatory rules:

1. Mounted on the front line, and connect the device should only be for the circuit breaker. Typically an intermediary between the two devices is also the electricity meter.
2. Installation work is done with fully de-energized power line.
3. The rated current of the machine is chosen equal to or slightly smaller with respect to the differential value of the device current.
4. Compounds should be performed in strict accordance with designations and manufacturer appended diagram.
5. Primarily performed connections on the load side with the liner and the zero-phase busbar devices corresponding terminals.
6. Tightening the terminal screws is done with some effort, sufficient for reliable connections, but without excessive force.
7. At last, after checking all connections are secure and free from defects, the device is connected to the output terminals of the machine.

Relation to installation, configuration and commissioning of the protective device can not stand formalities. All actions must be carried out carefully, with the exact calculation and duplicate checks.

In conditions of domestic household networks often try to solve the problem RCDs connection and automatic on their own.

However, this option does not guarantee safety. You should always choose professional installation - with the participation of specialists.

Conclusions and useful videos on the topic

This video explains lucidly and shows in what way a protection device in the electrical circuit. The different schemes:

After reviewing the RCD connection rules and the order of execution of works, as well as the installation of features in a single-phase mains with earth, you can try to do everything with their own hands.

However, this option is only justified if there is configured device protection and certain wiring work skills. Otherwise, the best solution would be an invitation to an electrician.

There is an experience of self-connection RCD? Please tell the readers about the nuances of selecting the appropriate protective devices and features of its installation. Comment publication, participate in discussions and add photos of their homemade. the feedback unit is located below.