A power generator includes at least one underwater turbine unit providing a housing having a flow channel therethrough and at least one turbine means mounted in the flow channel for rotation in response to water flow through the flow channel. Each connection has sufficient bandwidth to carry the call and terminates at a same destination point in said path. The pulsed supply of pressurized nitrogen blows blocked andor iced-up nozzles free again and thus ensures a more reliable operation of cooling a mass of a substance. A flexible structure, applicable to various systems to be monitored, is provided for the monitoring method. The second value is less than 10 percent of the first value.