This is the 6 Ampere model from the well-known STR-4 series of speed controllers, which includes models ranging from 1.5 to 14 A. The STR-4 allows you to control the speed of your three-phase fan. Thanks to autotransformer technology, it delivers a well-regulated output voltage to your fan, ensuring smooth motor operation and extending the fan's lifespan. Using the external rotary knob on the device, you can select from 5 speeds. An additional 230 VAC output is provided as soon as the rotary knob is turned from the zero position. This can be used to connect, for example, a damper or an operational status indicator lamp.