Contents
Where does the voltage appear on a floating DC power supply?
For floating DC power supplies, the voltage potential appears from the positive output terminal to the negative output terminal. There is no voltage potential (at least, none with any power behind it) from either the positive terminal to earth ground or from the negative output terminal to earth ground.
How is a floating power supply more flexible?
A power supply with a floating output is more flexible since, if desired, either the positive or negative terminal (or neither) can be connected to earth ground. Some devices under test (DUT) have a DC input with either the positive or negative input terminal connected to earth ground.
What causes current flow in a power supply?
Voltage causes current flow and will be hazardous only if the voltage is high enough and the source impedance is low enough (and your body resistance is low enough). Voltage produced across the output terminals of a power supply has near zero source impedance and is therefore hazardous above around 50 V DC.
Why is the power supply output floating from earth ground?
If you are using a power supply without connecting another source from earth ground to one of the output terminals (the output is floating from earth ground), there could be some stray current paths that could produce a voltage from one of the output terminals to earth ground.
How is a floating measurement of a voltage read?
A floating measurement reads the voltage between two points, neither of which is at ground potential. Floating measurements of fast AC signals are a challenge for conventional instruments.
How to measure the voltage between ground and DC?
If you were to make both measurements at once, with identical meters, you would find V- at -6V and V+ at +6V with respect to ground, and 12V of course between V- and V+. Did you measure using DC on the multimeter? You need to measure the AC voltage that might be present between output and ground.
How is the impedance of a DC power supply measured?
For DC measurements your meter’s input impedance will likely reduce the voltage to near zero. The 12V power supply is galvanically isolated from the ground via a transformer so theoretically there’s an infinite impedance between the primary (and ground of course) and the secondary. That’s why you measure 0V.