*5.4. Classification of Energy Storage System (ESS) Components*

An energy storage system (ESS) is divided into control, cooling, protection, and power control systems. The protection system includes a reverse current protection device in the event of power failure, Molded Case Circuit Breaker (MCCB) and surge absorbing element, overcharge protection circuit, and charging current limiting circuit. The representative power conversion systems include pulse width modulation (PWM) converters and input transformers. Figure 12 shows the ESS components.

**Figure 12.** Energy storage system (ESS) of the hybrid power system for a ship.
