Every larger data center's power supply begins with a connection to the main grid that the local utility company provides. Typically, data centers are connected to at least one diesel or gas backup generator to ensure uninterrupted operation even in the case of a large-scale power outage. A medium voltage is supplied to the power from both the local utility provider and the backup generator. Main Distribution Boards (MDBs), which are panels or enclosures that house fuses, circuit breakers, and ground leakage protection units, take and distribute low-voltage electricity to a number of endpoints, such as Uninterrupted Power Supply (UPS) systems or load banks.
Furthermore, MDBs monitor the incoming energy from the main grid and when sensing a power outage will activate the backup generator. Most data centers store sufficient fuel to keep the generator running for 24–48 hours.
Instead of directly distributing low-voltage electricity to sensitive computer electronic components and systems, MDBs pass through an Uninterrupted Power Supply (UPS) system that provides short-term power when the input power source fails and protects critical components from voltage spikes, harmonic distortion, and other common power issues.
Most UPS systems are designed to supply power to maximum load during an outage for at least 5 minutes. The backup generation has sufficient time for multiple attempts to start and take over the load from the UPS system during those 5 minutes.
This outline of a common data center power infrastructure explains roughly how modern data centers can provide sufficient power to meet the growing demand for connected IT solutions and how backup power ensures Datacenter wide smooth operation.