Consider than a differential automatic RCD differs from the unknown. The difference is conditional, but also weighty. Let's try to do without complicated terms, so as not to frighten unsophisticated reader unfamiliar words. On his fingers to explain complex concepts. Please note that the equipment is in the danger zone of water ingress can not be connected without the circuit breaker. This speaks directly to GOST. Also refers to a washing machine and dishwasher, other equipment installed on the territory of bathrooms and kitchens. There are other methods of laying wiring, but they are poorly suited for implementation within a typical apartment house.
What is the differential current
Scheme of current
In science industries under differential refers to the difference of some magnitude. Let's start with the simplest. Assume there is a certain schedule. For example, a parabola. In mathematics, it is important to find the so-called critical points. In these derivatives of the first or second order show any definite values change sign. Due to the specified property it manages to optimize production and other processes in the daily and professional activities.
It is important that the process of finding derivatives of the function is called differentiation. For this infinitesimal segment is taken on the vertical axis and divided into small interval on the horizontal. To define the border, using the difference between the beginning and end of the interval. Therefore, the difference is often called the differential. Although it is not very correct.
The electric current applied to find the difference between the input and output of the circuit. Suppose the device consumes 250 watts. At nominal voltage value in the circuit 220 the current amount 250/220 = 1.136 A. Surprised, but back to the ground (neutral socket) is obliged to leave exactly the same. This follows directly from Kirchhoff's law. The rule states that the current in a series circuit is the same. Our circuit is formed:
- The source of the substation.
- Automatic protection.
- Device, current consumption (e.g., machine washing).
- Chain neutral conductor, departing on the ground (in the ground).
Scheme differential current
Permissible slightly different scheme with the same meaning: how much electric current entered the apartment, as is required to get out. Accordingly, in the normal state the difference is zero. In the above case we say that there is no residual current.
How differential current helps to protect people and the apartment
Let us assume that there was a leak in the circuit. This is often caused by insulation fault, allowed other reasons. Then the balance is disturbed. The input current is not equal to the output. There is a minimum of two situations:
- Due to violations of insulation electrical current immediately begins to leak into the ground. For example, in the case of the heater will be through sewage. The charges will go into the ground, even on plastic pipes. Environment will serve liquid. The water does not conduct electricity, but in a lot of sewage dissolved salts, to play the role of the electrolyte. In the latter case, the leak will be immediately seen, differential automatic connection to avoid trouble.
- Insulation fault is not in contact with a conductive medium. Leakage is not formed immediately. Scene of an accident waiting event. Then human contact with the affected area becomes fatal. When a person will undertake to hand over the running water, and the other hand on the place of an electrical contact, a current will flow right through the body. At a voltage of 220 V is deadly. Lack of protection of the machine will cause a fatal outcome.
What is the differential Machine
RCDs are often confused with the differential machine
From the above it is clear that the differential machine helps to trace the leak. To this end, the difference between the input and output current. Inside the device there is a special relay: coil with magnetic cores. The design resembles scales, wherein the first bowl is the current input and the second output. So far so good, there is a balance. When a leak occurs, the scales on the side of the slope. This triggers the breaker.
Let's see what is different from the automatic differential RCD. Keyword - automatic. This applies to current overload. Simply put, the RCD constantly monitors the differential current, but does not save from a short circuit. In the latter case, consumption will grow dramatically until a combustion engine, for example, the motor windings of the washing machine or the wiring in an apartment. In addition to the RCD is required to include the second protection stage. Let's say, plug in the driveway panel designed for a certain current consumption.
Differential machine characterized by the presence in the composition of said second stage. If the RCD in some cases, able to burn out before us instruments of this situation class insured. Unlike jams that overload protection is reusable. This is not the fuse, which burns the inner core. What to put in the bathroom, is solved individually, but for complete security needs directly differential machine, not the RCD.
So summarize. Differential machine provides complete protection circuit for overload and leakage current. That frees the owner from having to worry further. In conjunction with the RCD is required to provide for methods of protection against overcurrent. As for the purchase, the store will have to examine the body. Differential automatic inscription shows, which featured the word "automatic". Indicating that the ability to protect the network from overload short-circuit.
Characteristics differential automaton
The main characteristics of the differential automata:
- The nominal operating current. The value of the equipment in the normal mode. Standardly taken consumption installed home appliances and reserve created in 1.5 - 2 times. For example, for the previous example about 2.5 A. Any differential automatic 4 A is suitable.
- Differential current tripping. This leakage value. For example - is considered sensitive differential automaton triggered when the difference of the input and output of 30 mA. With the help of this easy to control other security steps. Such delights in daily life, as a rule, are unnecessary.
- Differential automatic response time indicates how fast disconnect happens. Here, in addition to the desired destination (occurrence of leaks) isolated two additional components: an electromagnetic and thermal energy. The first direct indication of the amount of current overload (not differential and consumption), provoking trip. For example, for machine 16 A - fourfold excess (60 A). Triggering occurs almost instantaneously. Thermal component operates at much lower currents, is not critical. For example, 25 A. At the same time the overheating is growing rapidly, which causes shutdown of the differential machine. These two components are considered to be a distinctive feature. RCD circuits such automatic shutdown is not.
differential machine design is not as important as knowledge about the correct use. It is important to use a differential machine correctly.
When connecting with a differential automatic
Connecting Differential automatic switchboard would be a good replacement for standard fuses (fuses). Control is taken a whole apartment. It is no secret that every family lines, usually two. But given the fact that the load on them is different, select a suitable differential automatic hard. Posting frequently laid asymmetrically. At the first traffic jam hanging, for example, lighting rooms, the second has to the rest of the load.
In a typical consumption of 5 kW for an apartment is not always possible to put two differential machine at 16 A. For the above reason. At the maximum total current of 22 A wiser to select a single device, but powerful. For other installation options, often mounted protection directly into the bathroom. A differential machine usually present key performance audit, not everyone wants to run on a platform before the next turning on the heater. This question is required to consider in advance. Of course, unworkable differential automatic use is prohibited.
Wiring differential machine contains the housing. You see that there are input and output circuits. The layout is very simple:
- The letter N is labeled neutral. This is the neutral wire.
- Phase numbered figures 1 and 2. From the input and output circuits, respectively.
To find the neutral wire is a special tool. For example, a screwdriver with an indicator in the form of light bulbs will help to address the issue when testing sockets. If the slot to touch phase, luminescence occurs. As for the household appliance, no matter where the neutral conductor is. Connection is carried out without discrimination. What if the front differential connecting the machine does not perform this operation, and all will come out the other way around? We believe that performance will be compromised. Otherwise, there would have to be hard coded to lead to the corresponding findings of the differential phase of the machine and the neutral conductor.
Note that according to European standards equipment is connected to the grounding circuit. This side terminals on the plug and the reception of the socket. Ideally, this approach helps to avoid emergency situations, the breakdown of the insulation once the current goes to ground. These measures are commonly used where water, then often possible to localize the fault beforehand. Suppose heater heater struck on the body, but there is no ground. Then for some time nothing happens with high probability. But only the owner will open the valve, followed by a sharp jump in current consumption.
There is a risk of, for a short time. The second reason for connecting the ground becomes a correct operation of input filters. Often ripple current goes to the specified branch. If grounding is absent, the input filtering functionality is broken and the device is exposed, in addition to instability, increased risk of breakage. This is especially true of sensitive electronic components. If the ground is not in the house, it requires you to annihilate the chain, put into neutral. This is not entirely correct, in part saves trouble.
From the foregoing, readers should understand that the RCD in contrast to the differential machine is used where there is no risk of overload short-circuit. Frankly speaking, as applied to household appliances is not too important. It is better to put the differential machine.