This is a real world scenario that I had to trouble shoot in the field. One of the hardest task for me is to find and remove components that create a path to that would cause a fault on a floating power supply source. I have created a simple ground fault detector by using a switch and two lights. The two lights are in series and they sit across the power supplies positive and negative points. The switch connects between the lights and the other end of the switch goes to earth ground. I have included volt and amp meters to monitor the changing status. The four variable resistors represent any component, like a through beam sensor, RFID reader, proximity switch. In real world situations these components can fail like a variable resistor on a floating power supply causing a fault on either the positive or negative side of the power supply. To test the theory change the value of one of the resistors. A change in the current will calculate and will become different from the others resistor currents. This change will cause an unbalancing. Depending on which side the resistor is moved, when the switch is pushed one of the lights will become brighter than the other. That will indicated a fault on the power supply. When the switch is pushed the two volt meters will read a different voltage confirming a fault in the case. In an ideal situation every component would not fall below a balaced resistance resulting in a fault.
