The Knopp rotation meter indicates phase sequence from 60-600VAC, 25-60 Hertz. Insulated spring clamps.
The Knopp Phase Sequence Indicator is of the rotating-disc type. The K3 model can be used on three-phase, three-wire, 60-600 volt circuits, and on 25-60 cycle current. In addition it is suitable for use on frequencies above 60 cycles provided the circuit-voltages are equal to or exceed the following: 150V for 133 cycles, 200V for 180 cycles, 250V for 360 cycles, and 300V for 400 cycles.