Power disturbance generator

An apparatus selectively generates a disturbance in a three-phase supply voltage provided to a load. The apparatus includes input connections for receiving a first phase voltage, a second phase voltage and a third phase voltage of the three-phase supply voltage. The apparatus includes a voltage disturbance generator for selectively adjusting the amplitudes of the first, second and third phase voltages according to a first test method, a second test method or a third test method. Output connections are provided for connecting to the load to provide the load the first, second and third phase voltages as altered according to the first, second or third test method. In the first test method, a phase-to-phase voltage disturbance is introduced between the first and second phase voltages by altering the amplitude of the first phase voltage against the second phase voltage. In the second test method, a phase-to-phase voltage disturbance is introduced between the first and second phase voltages by altering the amplitudes of the first and second phase voltages in reference to each other. In the third test method, a phase-to-phase voltage disturbance is introduced between the first and second phase voltages by altering the amplitude of the first and second phase voltages in reference to a neutral connection. The apparatus provides for selecting the first, second or third test method without disconnecting any of the first, second and third phase voltages from the input connections, without disconnecting the load from any of the output connections, and without interrupting the load.