Hi Brian:
According to 6.10.3 and 6.3.1, the requirement is:
At 5 seconds, if the voltage exceeds 70 volts,
the charge must not exceed 45 uC.
Figure 3, Line A, is simply a 45 uC line as a
function of capacitance and voltage. This line
is derived from the formula:
q = C * V
where
q is the charge in coulombs
C is the capacitance in Farads
V is the voltage in volts
You have 80 volts and 4.4 uF:
q = 4.4 * 10^-6 * 80
q = 352 uC
You guessed right!
The test is performed at the maximum rated input voltage.
This give the worst-case voltage.
Best regards,
Rich
On 5/21/2013 9:33 AM, Kunde, Brian wrote:
What we call the Capacitor Discharge Test in the IEC 61010-1 standard section
6.10.3 says that voltage across the pins of the power cord must not be
Hazardous Live 5 seconds after disconnection from the supply. Most labs simply
check to see if the voltage across the pins are 60 volts or less at 5 seconds,
but the pass/fail criteria is the capacitive charge level described in 6.3.1 c)
which is 45uC.
6.3.1 c) points you to "Line A of Figure 3" but this chart seems to start at
100 volts. So how do I apply this chart if my 5 second voltage is 80 volts? Am I looking
at this wrong or should this chart go down to at least 60 volts? Is there a formula that
can be used instead of the chart?
In our specific case, we are measuring the discharge of an RF line filter which
has 4.4uF of capacitance across the line and the 5 second voltage is 80 volts.
My guess would be this filter fails as-is without and additional bleeder
resistor but when I discuss it with the company they pick apart the standard
and the chart at figure 3.
Another question. When you perform this test what line voltage do you use? The
highest nominal voltage or do you include +10%? For 230VAC equipment do you
test at 230Vrms or 264Vrms (373Vpk)?
Thanks to all for any input.
The Other Brian
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