The invention relates to an operational state determination apparatus (1) for determining whether a variation in a determined electrical parameter of an electrical network (2) is caused by a variation in an operational state of an electrical consumer of the electrical network. The electrical network comprises multiple electrical consumers (3, 4, 5) and a voltage source (6), wherein a variation classification unit (10) determines whether a variation in the determined electrical parameter of the electrical network is caused by a variation in the operational state of an electrical consumer of the network depending on a decision variable which depends on a variation in a measured voltage and a variation in a measured current of the electrical network.; This determination can be performed, without directly using the variation in the determined electrical parameter of the electrical network and is therefore less influenced by random voltage fluctuations in the electrical network.