A well-designed and reliably installed switchboard serves as the basis for the trouble-free operation of any electrical network. When buying a set of protective equipment installed in it, you often have to choose from several options. Some users prefer, along with standard circuit breakers (AB), to install in series a conventional RCD that reacts to emergency current leakage. Others prefer combined (combined) devices.
Differential machine or RCD, what to choose
A differential device (RCBO), as you know, combines the functions of AB and RCD and structurally consists of 2 nodes. The first of them protects the line from short-circuit and current overloads, and the second is triggered when an emergency leak appears in the circuit through damaged insulation or the human body. RCBO is actually a combination of these two devices housed in one housing (photo below).
When comparing them, the use of the categories "better or worse" is not entirely correct, since everything depends on the specific conditions of use of protective devices, namely:
- Availability of space in the control cabinet.
- Complexity of installation.
- User's ability to allocate funds for a more expensive product (RCBO).
Various combinations of factors influencing the choice of one of the options are also possible.
Panel dimensions and modular locations
In a situation where the user has a limited-sized shield at his disposal, they proceed from the space occupied by the equipment. In the first case, you will have to allocate three "positions", since the RCD will take two modular places plus one for the machine.
Note: The standard size of one module in width is fixed 18 mm.
In the case of a differential device, only two mounting locations are required.
That is, if the internal spaces in the dashboard are limited, and there is no desire and free funds to replace it, it is preferable to choose an RCBO.
Ease of installation
Any protective device is integrated into the supply line by connecting the phase and neutral conductors of the wiring to its contacts. For the installation of two such devices (AV and RCD), in any case, more switching will be required than with the same operation for RCBOs. In fact, the number of connections in the first case is twice as much, since you have to switch the input and output terminals of two devices instead of one. It turns out that from the point of view of labor and time costs, the choice of a differential device is more preferable (photo below).
Saving money
The average cost of a differential automaton is slightly higher than the price of two devices together (AV plus RCD). If the user is not limited by anything in terms of free funds, he will of course choose a RCBO (even if there is free space in the dashboard). In this case, the installation of the device will be simplified and modular cells will remain, which can always come in handy. If he is constrained in terms of money, then he has only one choice - AB plus RCD.