Electrical panels in industry and buildings are divided into different categories. But the main task of switchboards is to protect the circuits and control and command them and manage the distribution of electricity in the building and electrical equipment. These circuits include protective and control elements such as automatic switches, magnetic switches, life guards, control relays and displays, and prevent electrical circuits from short circuit, overload, fire, and electrocution, and start and control electrical equipment. makes it easier for us.
☑️ Types of building electrical panels
MDP main electrical panel
GDB or GDP common board
Table of units (SDP or SDB)
Weak flow panel
Elevator sign (if needed)
Diesel generator power distribution board (if needed)
UPS power distribution board (if needed)
1- The main electrical panel
The main power cable after entering the building It enters a panel that supplies electricity to all units of the building as well as electricity to common spaces. This board is called main electrical board or meter board or MPD. The main electrical panel, which is one of the building's electrical panels, has three parts:
< span style="font-size: 14px; white-space: normal;">The electricity input part (belongs to the electricity company).
counter part
service section
☑️ Inlet of the main power panel
The input of the main switchboard is a 4-core cable with a cross section of 16 mm square, three of which correspond to the phase and one of which corresponds to the PEN. Three phases are connected to the input of the automatic switch. The output of the automatic switch feeds the following two parts. Glass fuse input to protect the signal light and three-phase digital set multimeter Sectional fuse input The output of each glass fuse is connected to a signal light and the other end of the signal light is connected to zero. Each sectional fuse output is placed on a separate phase bus so that the input of each meter can be connected to these buses. In other words, after protection and for branching, we need a bus bar that includes a metal belt with holes on it. The input and output wires are closed on it by the cable connector, and it is protected from the contact of the bus bar with the body of the panel by insulating insulators. This part of the board is sealed by the electricity department, and its responsibility is with the electricity department. The fourth wire, which is a protective-neutral conductor, must first be connected to the ground bus and then jumpered to the null bus.
☑️ The main power panel meter
The main panel or meter panel is a panel that is placed at the entrance of the building and supplies electricity to all units and common spaces. This board is displayed in maps with MDP. The main cable often enters the fuse switch of this panel from the bottom, which is of the type that can be cut off under load.
After the main cable is pulled into the building, it enters this panel and according to the number of residential units and the presence of the communal panel, the number of meters of this panel is obtained. For example, a four-story building with an apartment unit on each floor has a main panel with five meters, one of which is for the general panel and the rest is for one of the units. The meter of the units is single-phase, and the shared panel is three-phase if the building has an elevator, otherwise it will be single-phase.
The power supply circuits to the units are located in the middle of the panel. In this part, contactors are installed so that the output of each fuse key enters the meter. It should be noted that when connecting the phase to the meters, the load balance must be established on the phases and the name of the phase should be connected to the meter using a label next to each input line. For this reason, phase control relays are used in some panels.
The phase control relay is a relay to protect the circuit against overvoltage, voltage drop, asymmetry and phase sequence, which is installed at the beginning of the circuit after the fuse. The neutral bus must be placed on the insulation (insulation bases). A neutral bus must be installed in the main switchboard for each unit, otherwise a life protector or RCD must be used in the miniature switchboard of the unit.
