How to correctly distinguish a differential machine from an RCD?

  • Dec 14, 2020
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Differential machine and RCD - 2 devices completely different in functionality. The differential machine, in addition to protection against leakage current, also includes the functions of the machine - protection against short-circuit and excessive heating of the conductor. But there is one serious problem - they cannot always be distinguished at first glance, and this must be done in order not to make unnecessary expenses. Still, there are a couple of proven methods that will help in this problem.

The easy way: name and labeling

Sometimes you don't have to invent a wheel, and the most difficult problem actually has a very simple solution. On any RCD and differential. the machine must contain the following data:

  • Device name.
  • Marking.
Figure 1: Differential automaton

Not necessarily the name and markings will be on the front panel, they can be made on the side, in the form of a special stamp on the case. And if everything is clear with the name, then the labeling of these products should be different:

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  • RCD - only current strength, no letter in front of the digital designation. For example, 16 A.
  • Dif. machine - before the rated current there must be a letter indicating the characteristic of the releases.
Figure 2: Example of an RCD

The above data should not be confused with the cut-off current - they are indicated the same for the differential and the RCD, only the value can change.

Figure 3: Some products have a name

Those in the know can look at the diagram

Any switching device has a diagram on the front panel. Mandatory elements of the scheme differential automaton Are releases. The RCD includes only a transformer with a button and this is clearly shown in the diagram.

Figure 4: Schematic and Marking - Key Differences

Of course, this method cannot be called simple, because not every user is able to read diagrams, but still, diff. the automaton of functioning elements in the drawing is always larger.

Dimensions

A controversial way of determining the functionality of the device, but it seems like the first differential automata differed from the RCD more impressive dimensions, because somewhere the release should have been placed - a solenoid and a bimetallic plate.

Modern differential automatic machines are a device that is not too different in size from a conventional bagger - compact, neat, without unnecessary parts or unnecessary elements. Moreover, all the outer parts have diff. the machine is the same as in RCD, for example, the Test button and the contact foot control lever.

What not to do

Some too competent "masters" suggest "just close the output with a screwdriver" to determine the differential automaton. It is strictly forbidden to do this, since the device may not be differential. automatic, and a classic RCD for which even a short-term short circuit is "like death".

Therefore, it is better to use simpler, and most importantly, safer methods. In 9 cases out of ten, these 2 devices can always be distinguished by their appearance, unless of course an RCD and a differential. the machine was made by not very Chinese craftsmen

Summing up

Unfortunately, the difference between a differential machine and an RCD can be determined only visually, otherwise the functionality of these electrical products cannot be recognized. But sometimes just a careful glance is enough - that will be enough.