Ground fault monitor detector

267

02:55:30

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. 

published 9 years ago

faceblast

9 years ago

that's handy to know! thanks

hurz

9 years ago

I dont get it. @samlogic30, let me ask you the following, you have four devices which have positive and negative and zero voltage input pins, which you represent with four poti's, right? But there is only one main power supply. Sure, your devices are in big trouble! Only if they consum a constant current it will work after some manual 0 volt alignment. Hope not all your devices are burned! What you need are at least 2 separated power supplies working minimum each within one quadrant. This way as power rail split is not working for dynamic current consuming devices. Or you have to waste a hell of power to split the power in pure class A mode. So cross current would be thumb of rule 10 times higher then the highest possible current spike your devices generate in sum.BTW, your testbulbs are actually this kind of class A splitter and will help to make operation more stable. I recommand a class B zero voltage automatic alignment like an opamp which can sink and source can do for you, and/Or a push pull transistor stage. Depends on the current requirements. 10mA or 100mA or 1000mA in total?

jaropower

9 years ago

Hoorahhhh

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