Main Distribution Board (MDB) Explained | ACB, Bus Coupler, ATS & Generator Backup

Imagine, in this building, all lights are on. Lift are running and everything is working perfectly. Suddenly, everything goes dark. Completely blackout. Even though power from the electricity board is available, the building has no electricity because the transformer has failed. This happen when power distribution is not designed or controlled properly. The main system that keeps everything

running is the MDB, called main distribution board. If the MDB is designed well, the building work smoothly. If not, the entire building can shut down. Hello everyone. Welcome back to my Rashid Iqbal channel. Today, I will explain the main distribution board or MDB in a very simple and practical way. MDB is the main point where electrical

power is received and then distributed to the entire building. Power comes from transformer or a generator, enters the MDB, and from here it goes to different panels like SMDB, lighting panel, and other equipments. In short, MDB is the heart of electrical distribution. Without it, we cannot safely control, protect, or distribute electrical power.

MDB is not just one box. It is divided into different sections, which we call cubicles. Each cubicles has a specific function. And together, they make the complete system. Now, first, I will show you incomer cubicle. This is the incomer cubicle. And here, we install ACB, which is air circuit breaker. This is the main entry point of power

into MDB. Power coming from transformer enters through this ACB. Now, why we use ACB here? Because incomer handles very high current. So, we need a breaker which can safely switch on or off and protect the system. ACB provide protection against overload, short circuit, and also allow us to switch on and off the entire MDB.