Abstract: An arrangement for collecting operational information on a closed system. The collecting system comprises an instrument to be connected functionally to a monitorable component of the closed system and a data collector comprising a register. The instrument collects operational information on the component that is transmitted onward to the data collector. The operational information is stored in the register. The collecting system can also comprise an analyzing module that determines the performance and/or power consumption of the closed system on the basis of the received operational information. The collecting system can also comprise a controlling module comprising a control algorithm and being functionally connected to the analyzing module for adjusting the performance or power consumption of the closed system on the basis of analysis information.