Mitsubishi FR-A740 series inverters are designed for various applications, including motor control and speed regulation. The "FR-A740" denotes the series name, and the numeric value following it represents the power rating of the inverter. 

For example, the Mitsubishi FR-A740-0.4K-CHT model has a power rating of 0.4kW, while the FR-A740-0.75K-CHT model has a power rating of 0.75kW. Similarly, the FR-A740-1.5K-CHT has a power rating of 1.5kW, and so on.

The FR-A740-18.5K-CHT model you mentioned has a power rating of 18.5kW, making it suitable for applications that require higher power output.

Please note, the "CHT" suffix in the model name denotes that the inverter is designed for use in high-temperature environments, adding extra heat tolerance to the unit.

These Mitsubishi inverters offer advanced features and control capabilities, making them suitable for a wide range of industrial applications that require precise motor and energy efficiency.