In today's world it is difficult to live without electricity. But for these types of energy, maximum protection is required. Therefore, quality installations capable of realizing this are always created. Modern developments in this industry create all conditions for mutual contact. RCD is a device that is difficult to do without.
Not everyone understands what it is. For clarity, it is worth knowing the designation, purpose, principle of operation. Information about this will be presented in this article.
About protection
It is difficult to imagine human life without electricity, but it is also necessary to create conditions for protection against defeat. The most elementary is the insulation of the wiring, but it will not work out completely. Because the circuit must have technical gaps and contact groups. But no one excludes the possibility:
- Wear insulation.
- Rush of wiring.
- Safety Violations.
- Improper operation, etc.
Therefore, creating insulation and grounding is the best solution. But this was not always enough. Therefore, many years ago, the first RCD appeared in Germany. Its designation is on the diagram that is presented below.
How does this system work? It assumes the presence of:
- Minimum leakage sensor .
- Polarized magnetic relay. Its sensitivity is not more than 99 milliamps.
To create something unique and more speedy in past centuries did not work due to the lack of appropriate materials. But already in the twentieth century, advanced developments appeared. The main thing is that protection against false alarms during bad weather was created. In addition, from a large size came to a more compact, able to sit on small stands.
Today, developers do not rest on their laurels, and in the near future protection systems against electric shock with artificial intelligence will be made. Thanks to the development, the device will perform maximum functions and, if necessary, notify users.
What kind of device and how does it work?
Everyone wants to know the designation of the RCD. As we have already noted, this is a residual current circuit breaker. What does the RCD protect against? The device has the function of protecting a person from electric shock, as well as from the possibility of fire of wires and other installations.
RCD - what is it in electrics? The action is based on laws that are based on incoming and outgoing electricity in closed circuits with maximum loads.
This suggests that the current should have one value, regardless of the phase of passage. Then everything is simple. When a bare wire touches a person or a gap, the indicator in the wiring changes its value and jumps. For RCD, this is a signal to turn off. It is such a system that is taken as a basis and implemented in installations.
The whole process is thought out to the smallest detail, so even minor energy leaks are recorded. To understand the principle of action, it happens like this:
- When there is no violation - I in = I out .
- If during operation there is a change in current in the network, the RCD is triggered and the network is turned off - I in> I out.
In this symbol, each has its own meaning - input current and output. RCD designations have their own. They are used in electrical circuits, and people with experience know about them.
Principle of operation
We already know the purpose of the RCD - this is protection against short circuits. Protection is carried out in the following areas:
- Short circuit. When the phase wire fails, it is on many household appliances - automatic machines, water heaters, dishwashers, etc. Breakage often occurs when the main element is heated.
- Violation of the installation rules when wiring. If it was removed under the plaster, then the RCD will work until the repair is completed.
- Lack of connection in the electrical panel. If conditions are created under which a slight loss of current occurs, then the overall performance of the entire installation is in question. For this reason, the protection is triggered.
If you look at the circuit, you can’t see the violation, and the RCD works. This indicates its accuracy and the smallest fixations. It also happens that an inexperienced person cannot find the reason for the disconnection. Only a thorough analysis will lead to a result.
Exceptions
Although there are exceptions to the rules. There are situations in which when an animal or person enters an electrical installation, the reaction does not occur (due to falling into phase and zero). For this reason, auxiliary protection is sometimes required.
Where is it found?
It is important to understand the purpose of the RCD and the principle of operation. The device has received extended use in everyday life, in many installations. Sometimes a circuit is developed at the input, but it is not excluded on each device. The fact is that RCDs for powerful small devices are cheaper. But in places of group stay of people it will be advisable to apply it extensively. In this case, the separation occurs in groups - all wiring is not turned off, which is convenient.
The most commonly used RCD is of the selective type. It is based on the same system of operation, but the response period is slower. The principle is not to turn off the entire network, but to work in sections (where the loss occurred, the system is de-energized there). For example, if music is played in a restaurant, there is a short circuit and a different charge of energy, then only the equipment will turn off, and the rest of the light will remain on.
In installations with alternating current, there must be re-protection with the RCD used for outlets. This applies to various household appliances. Of great importance when choosing is the bit depth. Not everyone can know how everything functions, but understanding security rules is imperative. The RCD system is not found so often, so some install it themselves.
The easiest device to understand is a water heater. What type of RCD and its application is here? There are several options:
- By voltage.
- By leakage current.
- By response time.
When a person is in the shower or just washes his hands with warm water, there will be an electric leak. The current will not hit it, since the RCD trips. Experts believe that this installation should function in the house, it is important to correctly distribute the wiring. Sometimes it’s impossible to do this on the old one due to incorrect input from the posts.
Device operation
When you press the "Start" button, the RCD starts. The voltage measurement of two points. One is the flow of energy, and the second is the required protection. No voltage should be present in the second section. When voltage appears on the site under the protection of reaching its predetermined value, the RCD disconnects the input. This is voltage protection.
Amperage protection
Through built-in transformers, the input and output current are measured. In normal mode, the difference between these indicators should be zero. When creating an emergency, when there is a leakage of current and the value carries a danger to a person or animal, the RCD disconnects the input.
Differential RCD
The alphanumeric designation of the RCD in this case is QFD1. It characterizes itself in terms of quick action. The greater the leakage current, the faster the shutdown speed. Other types of RCDs are triggered at specified time intervals. Always at any rate, the shutdown time is standard. The advantages of differential RCD are that current and voltage are measured.
Often when connecting a residential building, testers, as prescribed, are forced to make an RCD on the meter. This is stated in the technical connection, the wiring is carried out taking into account the requirements. In the switchboard, an RCD and an automatic machine are placed. As a rule, people without experience are engaged in this, and when the master sees this, many errors come to light. For this reason, no tripping occurs. Before installing it is worth understanding the operation of the RCD. What is it in electrics, we have already considered.
Error free connection
It is important to make a competent connection not only to the energy source, but also to each other. There are two main options:
- The most common and often used - the main machine - metering meter - RCD.
- What will work more efficiently: the main automatic machine - metering meter - selective RCDs - group automatic machine - group RCDs.
The RCD symbol on the electric circuit has its own symbol - D. Specialists in them read and understand how the whole system functions. There are rules that should not be violated:
- After exiting the residual current circuit breaker, a wire with a zero rating should not be connected by an earth terminal. Because it gives a chance of current leakage and false trips.
- It is important to connect the RCD completely. When the wire from the power goes by, current appears in the neutral wire. This is perceived by the system as a violation, and the protection is triggered.
- There are zero wires of sockets that are checked by RCDs. They must not be grounded. Because there will be a shutdown of the network with small fluctuations.
- When group protective installations are created, it is not possible to overlap the neutral wires at the incoming terminals. This will lead to a protective reaction of the entire installation.
It is for this reason that the preliminary scheme is always carried out. Otherwise, even a specialist can get confused. The process is not always complicated; there are devices that can be configured simply. It is important to consider all errors that can occur on the network. When everything is correctly entered into the circuit, the operation of the RCD brings effect. Today there are analogues of such a protection system. But the choice is to understand how they work.
note
Now we know the decoding of the RCD marking. In any case, when working with electrical appliances and installations, you must not forget about safety. It is worth periodically doing a visual inspection of all the wires. In case of damage, you do not need to delay repair. Otherwise, the energy supply will stop, as the protective device will operate in the room.