Vacon Oyj

Vacon Oy

Kimmo Rajakangas

Stefan Strandberg

Jaakko Ollila

Hans Carlsson

Pasi Kukkonen

Paavo Merilinna

Thermistor monitoring arrangement of an alternating-current electric motor controlled by a power transformer, such as a frequency converter, for at least one thermistor monitoring the temperature of the motor, in which is a power transformer (), in which is a power stage () and a control unit (), controlling an alternating-current electric motor () provided with a thermistor (), and into which power transformer, such as a frequency converter, an input circuit connected to a thermistor located in the motor is integrated, to which input circuit a safety circuit (a so-called Safe Stop circuit) that prevents unexpected starting or ensures safe stopping of the frequency converter is connected.

Protection arrangement of an electric motor

Method for synchronizing inverter units (INU, INU) that are connected in parallel and supply a motor, and a parallel connection arrangement, in which motor is either one winding, which is supplied by inverter units connected in parallel, or a plurality of parallel windings, in which each winding is supplied by its own inverter unit, in which parallel connection one inverter unit functions as a master and the others as slaves, in which method a telecommunications bus is arranged between the units, and in which each inverter unit has its own modulation cycle counter, which are synchronized with each other on the basis of telecommunications messages, preferably serial telecommunications messages. In the invention all the inverter units take into memory the value of their own modulation counter at the termination time of a telecommunications message (Mes), the master inverter unit sends the reading of its own counter in the following message to the other inverter units, and the other inverter units correct the reading notified by the master on the basis of the readings of their own modulation counters in the direction that makes the counters operate as simultaneously as possible.

Parallel connection of inverters

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Karperö, Finland

Kimmo Rajakangas