Yes, it probably combines leakage current and capacitance value and an unknown time. As such it tells you precisely nothing at all. About the best it can do is compare two capacitors of the same nominal value to see which one leaks the most - this is in many cases not very useful information.robert2017 said:
Something lost in (Google) translation from Russian I suspect!
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IF it means leakage current, it´s not a constant value by any means but depends on applied voltage, and more probable than not, it´s a complex non linear function, plus in any case, it can be presumed to decrease with decreasing remaining voltage, in principle tending asymptotically to zero or some very very low value.
Since none of these values is mentioned or stated or explained, your incomplete "definition" (to put it mildly) remains meaningless.
At least we would need a curve showing Vloss vs. applied instantaneous voltage (since it´s presumed varying along time) or at least a universally accepted definition, such as "Vloss is measured X seconds after Y volts are applied to the capacitor" , "Y volts being Z% of capacitor rated voltage" .
This definition *can* be expressed as a single % value as that meter screen shows.
Pity is that I just invented it to meet visible constraints, nobody says it meets what the meter makers think.
I’m sorry you don’t believe me
I think you are completely missing the point that “Vloss” is not an actual measurement that anyone here has heard of.
Ok so I've had a look at some source code for an ESR meter and we have the following pseudocode:
It seems that basically the 'VLoss' is a relabelled Leakage Current measurement that is derived as part of the capacitance measurement:
The term 'VLoss' is not specified within this particular ESR meter's source code but the 'leakage current' is feasibly just relabelled in the other meters when they copied the code.
Who knows. :shrug:
Code:
* charge DUT with up to 500 pulses until it reaches 300mV */
* if 300mV are not reached DUT isn't a cap or much too large (>100mF) */
* if 1300mV are reached with one pulse, we got a small cap */
* 10ms pulses (>47µF) */
* set mode to 1ms charging pulses (<47µF)and re-run with 1ms pulses (<47µF) */
* Check if DUT sustains the charge and get the voltage drop.
* Run for the same time as before (minus the 10ms charging time).
* - This gives us the approximation of the leakage.
* - The charge required for the ADC conversion can be neglected because
* C_S/H is just 14pF (very small vs. DUT).
* Take a second measurement with a specific delay to determine the self-discharge leakage current.
* Calculate the self-discharge leakage current - with Q = C * U and I = Q / t we get I = C * U_diff / t
* Raw = RescaleValue(Value, Scale, -8); /* rescale to 10nA */
* Cap->I_leak = Raw; /* leakage current (in 10nA) */It seems that basically the 'VLoss' is a relabelled Leakage Current measurement that is derived as part of the capacitance measurement:
Code:
/*
* Check if DUT sustains the charge and get the voltage drop.
* - Run for the same time as before (minus the 10ms charging time).
* - This gives us the approximation of the leakage.
* - The charge required for the ADC conversion can be neglected because
* C_S/H is just 14pF (very small vs. DUT).
*/
if (Flag == 3)
{
/* check self-discharging for measuring period */
TempInt = Pulses;
while (TempInt > 0)
{
TempInt--; /* descrease timeout */
U_Drop = ReadU(Probes.ADC_1); /* get voltage */
U_Drop -= U_Zero; /* zero offset */
wdt_reset(); /* reset watchdog */
}
/* calculate voltage drop */
if (U_Cap > U_Drop) U_Drop = U_Cap - U_Drop;
else U_Drop = 0;
/* if voltage drop is too large, consider DUT not to be a cap */
if (U_Drop > 100) Flag = 0;
/*
* Take a second measurement with a specific delay to
* determine the self-discharge leakage current.
*/
U_Zero = ReadU(Probes.ADC_1); /* get start voltage */
if (Mode & PULL_10MS) /* > 47µF */
{
wait1000ms();
}
else /* < 47µF */
{
wait100ms();
}
TempInt = ReadU(Probes.ADC_1); /* get voltage after delay */
/* calculate voltage drop */
if (U_Zero > TempInt) U_Zero -= TempInt;
else U_Zero = 0;
}
Code:
/*
* calculate capacitance
* - use factor from pre-calculated LargeCap_tableThe term 'VLoss' is not specified within this particular ESR meter's source code but the 'leakage current' is feasibly just relabelled in the other meters when they copied the code.
Who knows. :shrug:
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