1. First-level load.
The first-level load is an electrical load that will cause personal injury and death, and cause significant losses politically and economically.
2. Secondary load.
The secondary load is a load that interrupts the power supply and will cause damage to the main equipment, a large number of products will be scrapped, the continuous production process will be disrupted, and it will take a long time to recover, causing political and economic losses.
3. Three-level load.
General loads that do not belong to primary and secondary loads are tertiary loads.
Among the above three types of loads, the first-level load should generally be powered by two independent power sources, of which one system is a backup power source.