I recently purchased 2 little voltmeters they look like the sort that would go in a control or instrument panel they are connected with just 2 wires which provide the operating supply ( they light up green and red) however the green one states it will work between 20and 500 volts and the red one between 60 and 480 volts. When they are both on the green one indicates normally around 241 volts the red one shows 235 volts why the discrepancy I know it's not much but makes you wonder if one of them is lying. Secondly I've noticed that the green one tracks voltage changes faster than the red one and that a few times the green one jumps down to 238 then up to 241 multiple times while the red one stays the same and I think can see a slight flicker in my filament lamps when this is happening incidentally both meters are connected to the same plug a 2 pin 5 amp one
. Now I'm guessing that these effects are caused by the inductance and capacitance of not only the diodes but other parts of the wiring too.
As others have said, not really.
The main effect is from the fact at the AC waveform is feeding a capacitor (with a voltage on it) through a diode. If you consider the circuit, the current will be zero until the AC voltage reaches the capacitor voltage then there will be very little resistance to current as the AC increases to maximum charging the capacitor as it does so, then, once past maximum, the AC voltage will soon be lower than the capacitor voltage and the current will again drop to zero.
The current flowing can be approximated as a 50Hz waveform with a 3rd harmonic of 1/3 the size superimposed though there will be other harmonics generated.
I am led to believe that the worst case is a power supply running at about 2/3rd rated load (very common). In a 3 phase supply, this will give rise to a neutral 3rd harmonic current of twice the phase current hence double sized neutrals being specified in computer farms.
. Now I'm guessing that these effects are caused by the inductance and capacitance of not only the diodes but other parts of the wiring too.
As others have said, not really.
The main effect is from the fact at the AC waveform is feeding a capacitor (with a voltage on it) through a diode. If you consider the circuit, the current will be zero until the AC voltage reaches the capacitor voltage then there will be very little resistance to current as the AC increases to maximum charging the capacitor as it does so, then, once past maximum, the AC voltage will soon be lower than the capacitor voltage and the current will again drop to zero.
The current flowing can be approximated as a 50Hz waveform with a 3rd harmonic of 1/3 the size superimposed though there will be other harmonics generated.
I am led to believe that the worst case is a power supply running at about 2/3rd rated load (very common). In a 3 phase supply, this will give rise to a neutral 3rd harmonic current of twice the phase current hence double sized neutrals being specified in computer farms.
