This article will discuss how you can determine what type of RCD do you have?: electromechanical or electronic without connecting them to the mains. Such a need may arise, for example, when purchasing in a store or you already have an RCD, but you do not know what type it is.
We will not consider the design and operating principle of RCDs in this article - this is a separate, extensive topic that will soon be covered in separate publications. Therefore, if you want not to miss the release of new interesting materials on this topic, subscribe to the news on my website, the subscription form is at the top right of this article.
Let's touch briefly design features RCD:
— electromechanical RCDs do not require additional nutrition. To trigger them, the presence of a differential leakage current is sufficient;
— electronic RCD Power is required for the amplifier board, which they usually take from the mains supply.
These two types of RCDs behave differently during emergency operation of the electrical network, see the article for details, so it is important to be able to distinguish these types of RCDs from each other.
For the test, we will use a battery, for example, a AA or 9V crown type battery and two wires. For convenience, it is advisable to use wires of different colors; in our example, we will use red and blue wires.
Before we start checking, we connect the wires to the battery, first secure them with electrical tape, wrapping them around the battery. TO " + "connect the batteries with the red wire to " — » connect the blue wire.
Then we cock the RCD control lever, moving it to the on position.
We take the prepared battery with wires and touch the wires to the input and output terminals of one of the poles of the RCD. The electromechanical RCD should trip when connecting the wires. If it doesn’t work, try connecting the wires in a different polarity, i.e. where did we connect plus batteries, now connect minus and vice versa, and look:
- if it works - with us electromechanical RCD;
- if there is no with both polarities - we have RCD electronic.
When tested with a battery connected to one of the poles, electronic RCDs will not work, since there is no supply voltage necessary for their operation.
I explained in detail why electromechanical RCDs are triggered in the video, which you can watch at the bottom of this article.
RCD type A should operate in any polarity of connecting the battery to the RCD pole.
RCD type AC will work with one polarity, so if the RCD does not work, try changing the polarity of the connection. You can connect the battery to any of the poles of the RCD.
More details about how to check the type of RCD - electromechanical or electronic, watch the video:
In this simple way you can check the type of RCD.
Useful articles
Hello, dear guests and readers of the Electrician's Notes website.
So, there was a zero loss on one of the apartment groups. At the same moment a malfunction occurred in dishwasher in the form of a phase short circuit to its body, i.e. a life-threatening potential “reached” the conductive body of the machine. If in such a situation a person (God forbid) touches the body of the machine, the electronic automatic machine will not work due to the lack of power to its internal circuit, and the person will receive a blow electric shock.
Read the following articles about the consequences of electrical injuries:
Of course, the likelihood of the above example occurring is very low. It is necessary that at one moment the zero also breaks, and a phase short circuit occurs to the housing in electrical appliance, but nevertheless this must be taken into account.
Let's continue the comparison. Electromechanical devices have a simpler and more reliable design. But electronic devices have a more complex design and the likelihood of failure is much greater; for example, semiconductor elements or a microcircuit may fail.
What to choose? Electronic RCD or electromechanical?
This suggests a logical conclusion that electronic RCDs and automatic devices are less reliable compared to electromechanical ones. But they are no less common, because... They are cheaper in cost than electromechanical ones. Nevertheless, I recommend that everyone use electromechanical RCDs and automatic devices.
Currently, electronic automatic devices are equipped with an overvoltage protection function, i.e. if the voltage at its terminals increases above 240 (V), it will automatically turn off. An example of such a difavtomatic machine would be the AVDT-63M from EKF. But personally, to protect against increased voltage, I recommend using devices specially designed for this purpose, for example, and.
How to distinguish an electromechanical RCD from an electronic one?
How to distinguish an electromechanical RCD from an electronic one? This is a fairly common question that I am asked not only by readers of the site, but also by ordinary citizens, and even by fellow electricians. Unfortunately, most sellers in stores and shopping centers also do not know the answer to this question.
So, there are several ways. Please note that all of the above methods are carried out with devices disconnected from the network.
1. Scheme on the RCD body
The very first, but not the easiest way is to look at the diagram shown on the RCD body.
For electromechanical RCDs, the diagram shows a differential transformer, the secondary winding of which is directly connected to a polarized relay. A relay is usually designated by a rectangle or square. From it there is a mechanical connection with a dotted line to the trigger mechanism of the RCD. There are no connections (lines) with the mains supply voltage in the diagram.
Here, for example, is the electromechanical RCD VD1-63 16 (A), 30 (mA) from IEK.
Another example of an electromechanical RCD VD1-63 16 (A), 30 (mA) from the TDM company.
As you can see, the schemes are absolutely the same.
For electronic RCDs, the diagram always shows a board with an amplifier in the form of a triangle (this symbol amplifiers according to GOST). You will also notice where the power supply for this board comes from: from phase and zero.
Here, for example, is an electronic automatic circuit breaker AVDT32 C16, 30 (mA) from IEK.
All diagrams also show the “Test” button and its connection diagram.
I'm afraid that the first way to distinguish one type of device from another is not entirely simple, and without the appropriate experience you can easily make a mistake. Therefore, I propose to move on to the following methods, which will give a 100% correct result.
2. Battery test
This method requires batteries, or in simple language, batteries. You can use at least a AA 1.5 (V), R14 1.5 (V), or a 9 (V) Krona, in general, any batteries that you find at hand - just make sure they are charged .
Let's turn on the RCD or automatic circuit breaker. Let's connect two wires to one of its poles. For example, there is one wire to the input (1), and another wire to the output (2) of the same pole.
Then we connect these two wires to the battery terminals: “+” to terminal (1), “-” to terminal (2).
When the wires are shorted to the battery terminals, the battery discharge current begins to flow through the closed contacts of the pole. A current surge is induced in the secondary circuit of the differential transformer, which causes the polarized relay to operate. The relay acts on trigger and the RCD turns off.
If the RCD turns off, then it means it is electromechanical, but if it does not turn off, then change the polarity of the battery and repeat the test.
If this time the RCD turns off, then it means it is electromechanical, but if it does not turn off again, then it means it is electronic and does not work due to the lack of voltage on the amplifier board.
3. Permanent magnet
Take a medium-sized permanent magnet and present it to the body of the RCD or automatic device.
Naturally, the RCD must be turned on. Move the magnet slightly along the front panel and side of the case.
If the RCD works, then it is electromechanical, but if not, then it is electronic.
As usual, watch the video based on this article:
P.S. That's all. I hope that this article will be useful to you. Thank you for your attention.
Residual current switches, often simply called RCDs, are designed to protect against current leakage. Such devices can hardly surprise anyone, because they are installed in almost every panel. Most owners of apartments and houses, even those far from electrical engineering, have realized that installing an RCD is necessary condition security and stability of power supply. But not everyone realizes that the devices are produced differently not only in external, but also in internal design. Read also the article ⇒
How to distinguish devices from each other?
RCDs are produced in two versions - electronic and electromechanical. The differences between the two types of devices are fundamental. You can distinguish them using three simple techniques.
According to the electrical diagram shown on the case
This method of determining the type of protective devices can be called the simplest; it does not require the use of any devices or tools. The main thing is to remember the differences in the schemes.
On the body of any model of RCD or difavtomat you can find a circuit diagram internal structure device. At their core, circuits are divided into two main types - electromechanical and electronic. Each scheme has its differences, but they are not significant.
Briefly about the design and principle of operation, the basis of the difavtomat and electromechanical RCD is a polarized relay and a differential transformer. When a leakage current forms in a controlled circuit, a differential current appears in the secondary winding of the transformer, leading to the operation of the relay. When triggered, the relay acts on the trigger mechanism, which turns off the protective device.
Tip No. 1: Thus, you need to find the icon of a polarized differential transformer relay on the diagram.
The latter is schematically indicated by an oval-shaped icon around the neutral and phase conductors; the relay is marked in the shape of a square or rectangle. The connection between the transformer and the relay is carried out through the secondary winding, depicted as a solid line. The dotted line shows the mechanical connection with the escapement mechanism. Also on the diagram you can often see the “Test” button, but in some models it is not provided for by the design.
For automatic circuit breakers and electronic RCDs, a different structure and, accordingly, a different circuit are provided. From the very name of the devices, we can conclude that the operation of the devices is controlled via an electronic board.
If a leakage current occurs in the circuit to be monitored, then a differential current arises in the secondary winding of the differential transformer. The electronic board detects its presence and generates a pulse that triggers the relay. A command is sent from the relay to the trigger mechanism, which turns off the protective device.
The elements that make up electronic boards are much more compact, and therefore electronic circuit breakers and RCDs have much more compact dimensions. On sale you can also find single-module electronic protective devices that are no larger than a single-pole circuit breaker.
In the diagram, in addition to the differential transformer, you also need to find the electronic board of the amplifier, which is indicated in the form of a triangle. Since no board is capable of operating without power, additional lines are necessarily shown on the diagram.
From the above, the following conclusions can be drawn:
- If there is an oval in the diagram located on the phase and neutral conductors (differential transformer) and a square (relay), connected to each other by a solid thin line, then we are dealing with an electromechanical differential circuit breaker or RCD.
- If the diagram has an oval above the phase or neutral conductors (differential transformer) and a square denoting a relay, connected to each other by a solid line passing through a triangle (amplifier board), to which a pair of supply lines comes, then we are dealing with an electronic differential circuit breaker or RCD .
Using a battery
Determining an electromechanical and electronic protective device using a battery can be called more complex than simply looking at a circuit diagram. To work you will need:
- charged battery;
- screwdriver;
- a pair of wires.
In addition, if you determine the type of RCD or automatic circuit breaker in a store, it is unlikely that the seller will want to give the buyer the product in order to connect something to it and conduct incomprehensible experiments. Plus, most devices are sold in sealed boxes, which the seller also does not want to open.
This method still has a right to exist. For example, a RCBO manufactured by the well-known company Schneider Electric is used.
The work will not cause any difficulties even for people who do not consider themselves experts in the field of electrical engineering.
The first wire is screwed to the zero pole on top, and the second wire to the bottom pole. Next, you will need to turn on the RCD or automatic circuit breaker, for which you need to cock the control lever.
The remaining free ends of the wires are connected to a charged battery, the type of which is not important. When you turn off the device, you can conclude that it is electromechanical. If the device turns off, you should change the polarity of the connection of the wires on the battery and try to make the circuit again. If after this the device turns off, then it is definitely of the electromechanical type.
For what reason are electromechanical automatic devices and RCDs triggered by a regular battery? The fact is that once in a closed circuit, the battery discharges, releasing current into one pole. Therefore, a differential current is formed in the secondary winding of the differential transformer, which is quite sufficient to operate the polarized relay.
Carrying out such an experiment is possible for any pole - both phase and zero. Electromechanical device will turn off anyway.
Using a permanent magnet
There is also nothing complicated when determining the type of protective device using a magnet. The only problem that may arise is to find a permanent magnet of the required size (a third or a quarter of the size of the device).
Actions are performed in the following sequence:
- pick up a difavtomat or RCD;
- the device is turned on by raising the lever;
- The magnet is circled in the immediate vicinity of the front panel and the side of the device in a circular motion.
If, when performing circular movements, the device does not respond by turning off, then it is concluded that it is electromechanical.
Tip No. 2: This method cannot be called accurate and gives a 100% guarantee, since the magnet power may not be sufficient to generate a differential current.
Advantages and disadvantages of devices
Comparison of advantages and disadvantages protective devices It is convenient to perform both types in tabular form.
As a result, it should be noted that the most suitable option for installation in a residential electric meter is still an electromechanical automatic circuit breaker or an RCD. This type of device is widely represented on the modern domestic market.
RCD - device protective shutdown or a residual current switch is installed to protect a person from electric shock. However, not everyone knows that there are two types of RCDs: electronic and electromechanical. In this article we will talk about the differences between RCDs different types and how to determine the type when purchasing.
Operating principle
In general, the principle of operation of an RCD is as follows: when the current through the phase wire differs from the current through the neutral wire, a relay is triggered, which disconnects the load. Current detection occurs using a differential transformer and a polarized relay.
A situation where currents of different magnitudes flow through the phase and neutral wires can occur if some electrical appliance leaks onto the housing. A leakage to the housing occurs if the insulation of one of the conductors of an electrical device is damaged and touches the housing; this applies to both the insulation of the winding wires of electric motors and the internal wiring of the device.
If the housing is grounded, the RCD will trip. If the case is not grounded, the current will have nowhere to flow, but if you touch it with your hand, the current through your body will go to the ground, at which point the RCD will work and protect you. Even if you accidentally touch an open phase wire, nothing will shock you, because... The RCD will open the circuit, because current will leak through the circuit: Phase wire - your body - ground.
Each of the RCDs is configured for a certain leakage current; this is a characteristic that describes at what current the relay in the RCD will disconnect the load from the electrical input. This is the main characteristic.
Electronic and electromechanical
Electronic - as the name implies, it contains in its case a board with electronic components that are responsible for its operation. Electromechanical - contains a differential transformer in its housing. On the body of both types of RCD there is an operation indicator and a button for checking the serviceability.
When you press a button, you short-circuit the phase to zero through a resistor. In this case, the button closes the phase before the transformer to zero after the current transformer or vice versa, depending on how you connect the wires. As a result, the transformer detects the current difference between phase and zero.
The current of this circuit is set using a resistor, and to ensure that the sensitivity of the RCD is correctly matched to the nominal value, its corresponding resistance is selected, but as consumers and users, these subtleties do not particularly concern us.
Differences in operation
For the electronic RCD to operate, power must be supplied to the board; it is taken directly from the already connected phase and zero. An electromechanical RCD will operate even without voltage. A logical question arises:
If the RCD protects against electric shock, then how will it occur if there is no voltage?
We are talking about emergency situations in electrical wiring. For example, if a zero has burned out on the switchboard at the entrance or at the entrance to the house/apartment. No electrical appliance will work in the apartment. The phase will remain in the sockets, and if there is a breakdown somewhere on the housing, and you touch it, you will certainly receive an electric shock, unless of course you have an RCD at the input.
But the situation is not so clear-cut. An electromechanical RCD will work, because it does not require full power, but requires a current difference between the wires. That is, when you touch a phase wire or the body of a damaged electrical appliance, a leakage current will flow through your body to the ground through the phase wire, but not through the neutral wire. There is a current difference - the relay is triggered.
In case of use electronic device protective shutdown protection will not work, since its board is de-energized.
Also, do not forget that in our networks voltage surges occur quite often, and electronics do not like such “accidents”.
How to distinguish RCD various types upon purchase
First of all, when purchasing, pay attention to the diagram shown on the case; in the picture it is enclosed in a red square.
On the left is an electromechanical RCD, and on the right is an electronic RCD. But the schemes are very similar, at first glance you may not notice the differences, let's take a closer look at them.
In this figure you see a breakdown of the circuit elements of an electromechanical protective device. Pay attention to what is highlighted in red - this is the power line of the board with electronics.
Let's look at a selection of RCD circuits to consolidate.
Here is an example of a difavtomat with an electronic RCD. Pay attention to the two lines supplying the board.
This device is electromechanical. In the diagram you see that only the signal from the differential transformer is connected to the relay.
The test method is to connect the battery to one of the poles of the RCD, the principle of operation is similar - the battery current will flow through one of the lines, the differential transformer will operate, this method only works with ELECTROMECHANICAL devices. Electronic in this case will not work, because the board remains de-energized.
Well, don’t forget about the phenomena of electromagnetic induction, because if you use a field permanent magnet If you apply an EMF to the differential transformer, the relay will also work and the RCD will turn off, again the ELECTROMECHANICAL method works.
To summarize, the electromechanical RCD provides more reliable protection than electronic. It will work even if there is no power. In residential premises it is better to use electromechanical. To check it when purchasing, pay attention to the diagram, and if the sales consultant allows you, use the method with a battery; it is worth noting that if the RCD does not work on the battery, change its polarity.