Knopp K-3 Phase Sequence Indicator
The K-3 Phase Sequence Indicator is of the rotating-disk design; there are no lights to burn out. All internal connections are soldered and there are no exposed metal parts on the housing.
Its three leads are color-coded (red (A), white (B), and blue (C)) for easy connection (other colors are available upon request). The leads are 36 inches in length (other lengths available upon request).
The K-3 is designed for operation from 25 to 60 Hertz and from 60 to 600 Volts. Other models (including a panel-mount version and a 400 Hz. version) are available.