The exact components may vary slightly depending on the specific  model and manufacturer, but the following are common components in  UPS systems:

The power module is the building block of modular UPS. Each power  module typically includes components such as rectifiers, inverters, and  DC-DC converters. These modules are hot swappable and can be easily added or replaced without shutting down the entire system.

Control module
Control module management and coordination of power module  operations. It monitors various parameters such as voltage, current, and  temperature, and ensures seamless collaboration of power modules.  Control modules typically include microprocessors for intelligent control and communication functions.

Bypass module
The bypass module provides a method of bypassing the UPS system and  directly supplying power to connected loads from the public grid during  UPS failure or maintenance. Even if the UPS is offline, this ensures continuous power supply.

Battery module
The battery module stores electrical energy and provides it to the load  during power outages or when the input power exceeds acceptable  parameters. These modules may include maintenance free sealed  lead-acid batteries, lithium-ion batteries, or other energy storage technologies.

STS switch
The static switch is a critical component that automatically transfers the  load from the normal power path to the bypass path in the event of a UPS  failure. This ensures a smooth transition and maintains power continuity.

Shell and rack
These components are installed inside the casing, which can be in the  form of a rack or independent cabinet. The shell provides protection,  organization, and in some cases helps manage heat dissipation.

Modular expansion slot

UPS systems typically have expansion slots or ports to accommodate  additional power modules or accessories for future scalability.