Selective parallel running method for measuring/control devices

A method of controlling parallel operation of a plurality of transformers in a parallel circuit in which a tap changer with a control sensor is associated with each of the transformers and all control sensors are connected together by a communications connection, the method comprising the steps of:

• generating a measurement with each of the control sensors;
• transferring at least one of the measurements of the control sensor of the transformers by the communications connection to N−1 control sensors;
• calculating of a controlling deviation caused by a circuit reactive current for each control sensor on the basis of the measurements of the control sensors;
• actuating the tap changer associated with each transformer by the control sensor as a function of the calculated controlling deviation such that minimization of the circuit reactive current is carried out for the respective transformer;
• causing absence of at least one signal of at least one of the control sensors by interruption of the communications connection at an instant and detecting the absence of the at least one signal of the at least one control sensor by all remaining control sensors;
• and
• determining the controlling deviation required for minimization of a circuit reactive current of at least one control sensor affected by the interruption of the communications connection, of a transformer on the basis of the measurements received by the communications connection prior to the instant and transferred from the associated control sensor of at least one further transformer, and including the individual instantaneously measured measurements of the control sensor affected by the interruption, of at least one transformer in the determination.