"停机检修时间" can be translated as "downtime for maintenance" or "shutdown maintenance period" in English.
"Downtime for maintenance" emphasizes the period during which the equipment or machine is not in operation due to maintenance activities.
"Shutdown maintenance period" specifically highlights the time frame when the shutdown occurs for the purpose of maintenance.
Both expressions are commonly used in industrial and technical contexts to describe the time allocated for equipment maintenance when it is not operational.