Elaboration:

• DB (Distribution Board):

  A DB, also known as a panelboard or breaker panel, is a component that receives electrical power and distributes it to multiple circuits. It typically includes a main switch, fuses or circuit breakers for each circuit, and may also incorporate RCDs (Residual Current Devices) or RCBOs (Residual Current Breakers with Overcurrent Protection) for enhanced safety. 

   
• SDB (Sub Distribution Board):

  An SDB is a secondary distribution board that receives power from a main distribution board (MDB) or another SDB and further distributes it to local circuits. It’s essentially a way to break down larger power distribution systems into smaller, more manageable sections. 

   
• MCC (Motor Control Center):

  An MCC is a centralized unit for controlling, protecting, and managing multiple electric motors. It contains various motor control and protection devices like MCBs, contactors, timers, relays, and more. MCCs are crucial for industrial automation and ensuring efficient motor operation in factories and large-scale facilities. 

   
• Relationship:

  In a typical setup, power comes from a source (like a transformer or upstream panel) to a Main Distribution Board (MDB), then to SDBs, and finally to MCCs or other loads. The MDB distributes power to the SDBs, which then distribute power to individual circuits or motor control centers.