In modern housing, 3-phase input is increasingly used. The main advantage of a 3-phase network is the ability to increase the total power consumption. A common criterion for the feasibility of organizing such a power supply scheme is the excess of the standard power consumption of 7-10 kW.
When switching to a 3-phase input scheme, it is necessary to solve a number of problems, one of which is the construction of a switchboard. In practice, five main schemes are used, which are discussed below.
Simplifications used
To illustrate possible schemes, further in the text, figures are used that have the following features
- for clarity, only key components are shown in the figures;
- some of the connections (mainly PE and N wires) are not shown when entering the cable);
- fire-resistant RCDs are considered present by default and are installed in their designated places;
In addition, we point out that the location of the shield does not affect the applied scheme.
The simplest scheme
The simplest circuit, which is shown in Figure 1, in many ways represents a three-phase three-phase circuit, and its differences from that are determined exclusively by the technical features of the 3-phase element base.
It goes without saying that several circuit breakers can be connected in parallel to a particular phase. Their number and response threshold depend on the specific local conditions.
Due to the insufficient level of protection, the use of such a scheme is not recommended.
Simplest 3-phase circuit
If there is a powerful load in the list of consumers, it is convenient to connect it to a three-phase network, which somewhat changes the block diagram of the shield. The latter is shown in Figure 2 and differs from the circuit in Figure 1 only by the presence of an additional three-phase circuit.
The simplest circuit with an RCD
In this version of the flap construction scheme, the structure of which is shown in Figure 3, the main drawback is eliminated diagrams in Figure 1: the absence of an RCD, which significantly increases the level of operational safety created wiring.
The main drawback of the circuit is the lack of selectivity for leakage currents: the operation of the RCD de-energizes the entire network.
Circuit with increased selectivity for leakage currents
The circuit in Figure 4 differs from the circuit in Figure 3 in that an additional RCD is added to it, which is shown in the left side of the circuit and from which the left circuit breaker or their group is powered, designated as AB1. The response threshold of this RCD is naturally chosen less than the threshold of the group RCD, which in this case becomes the main one.
Scheme on individual differential machines
The schematic of this variant is shown in Figure 5 and surpasses the other variants in terms of operational flexibility. This is achieved due to the possibility of individual selection of this module, depending on the power of the served load.
The strongest side of this option is the maximum complete independence of the loads from each other.