A thyristor circuit comprising at least one series circuit in which two or more thyristors are connected in series. Each thyristor is parallel-connected to an RC member. A control device can energize the thyristors individually and independently of each other by a control signal, so that each thyristor can be individually switched into its conducting condition. During a test sequence, the thyristors are switched successively into their conducting condition, wherein, in a series circuit and/or in the thyristor circuit, respectively only one thyristor is in its conducting condition. While a thyristor is conducting, the capacitor of the associate RC member discharges and produces a thyristor current. As a result, the conducting condition is maintained until the thyristor current falls below the holding current. The control device can use the thyristor voltage and/or the thyristor current to evaluate the function or the switching behavior of the thyristor.
