In power and electrical engineering, differential automata or residual current devices are widely used to provide effective protection against electric shock. But among users, the question often arises of how to distinguish an RCD from a difavtomat. Many do not notice the fundamental differences between these devices.

What is the difference between a differential machine and an RCD

The main differences between these two devices are not only external, but also functional. In order to accurately distinguish devices, you need to know their name and designation. So the RCD is known under the name of the differential switch (VD), and the differential machine is called the automatic differential current switch (RCD). These abbreviations are used in the marking of the respective apparatus.

The main difference between both devices lies in their functionality. Both of them are switching devices, in the differential machine in one case the functions of an RCD and a circuit breaker are combined, and the residual current device performs its own protective function. Thus, the RCD only protects against leaks due to damaged wiring, and the difavtomat, in addition, provides protection for the electrical network from overloads and short circuits. In fact, the difavtomat is a residual current device with wider protection capabilities.

The actual differences between the RCD and the differential machine

Most protective devices of various types are very similar and in some cases it is not always possible to distinguish between them without some specific knowledge. You can determine the ownership of a particular device in different ways.

First of all, an inscription characterizing a particular device is used. As a rule, it is applied from the front or side and reflects the exact name of the device. Additional information is contained in the label. If only is present in the designation, and there is no letter designation before the number, then this device is a residual current device. If, in front of the figure indicating the nominal value of the current, the letter B, C or D is affixed, this means that the device belongs to differential automatic machines.

The following method is well suited for people versed in electrical engineering. A wiring diagram is applied to the body of each device. If there is a picture of only a differential transformer together with the TEST button, the device should be classified as an RCD. If the diagram additionally contains an image of the windings of an electromagnetic and thermal release, this means belonging to differential automata.

Accurate identification of the ownership of protective devices allows them to be used correctly and effectively in a given electrical system.

The use of RCDs and differential automata

The decision to use a particular device is made based on the availability of free space in the electrical panel. The differential circuit breaker takes up much less space than a residual current device and a circuit breaker installed separately. An important factor is the purpose of the device. As a rule, any single device is quite capable of protecting the differential machine. If it is supposed to use group loads, in these cases it will be preferable to use an RCD.

The quality of the equipment used is of great importance. Individual devices - automatic devices and RCDs - are more reliable and of high quality compared to Dif automatic devices, consisting of two devices.