This video demonstrates a test we did on Maxwell SCR 3 phase power regulator
The instruments you are able to see right away is an oscilloscope which shows the square wave of the load, the one our test engineer holds on hand is a standard signal generator which generates 4-20mA standard input signals, we feed the SCR with a small input and gradually increase the input, as you can see from the video, The lights in the video turned brighter as the input increase. And the 3 voltage meter shows the voltage of each phase, Voltage of each phase increases from 0V to somewhere close to 380Vac, other features like soft-start, minimum and maximum output, manual control, over temperature protections are also available with this SCR.
RS-485 Modbus communication are also available.