Electronics:Tips And Techniques
From: gingertube
This was the first time I've ever seen anyone doing it by the numbers
and I thought it important for many of us.
Given:
Aerovox BHC ALC40 Series caps 470uF and 450 V rated,
in series with 530V rails.
Leakage Current for ALC40 Series is quoted as:
0.003 Cr Vr or 10mA which ever is the smaller.
Cr is rated capacitance and Vr is rated voltage.
So do the calc Ileak = 0.003 x 470 x 10^-6 x 450
I get 0.6345 mA leakage current.
For the capacitors to share voltage properly
you want 3 to 5 times this current through
bleed/voltage equalising resistors.
So assume we want 2mA through those resistors.
With a 530V rail you have 265V across each cap.
Resistors calcuated as 265V/2mA = 132KOhms (maximum value)
I would strongly suggest you revert to 120K resistors across the caps.
Power Dissipated in each resistor = V squared on R:
R
= (265)^2 / 120K
= 0.585 Watts
Use 2W metal films, 3W metal oxide, or 5W wire wound.
Submitted and edited by SyncTroniX for use here.
This was the first time I've ever seen anyone doing it by the numbers
and I thought it important for many of us.
Given:
Aerovox BHC ALC40 Series caps 470uF and 450 V rated,
in series with 530V rails.
Leakage Current for ALC40 Series is quoted as:
0.003 Cr Vr or 10mA which ever is the smaller.
Cr is rated capacitance and Vr is rated voltage.
So do the calc Ileak = 0.003 x 470 x 10^-6 x 450
I get 0.6345 mA leakage current.
For the capacitors to share voltage properly
you want 3 to 5 times this current through
bleed/voltage equalising resistors.
So assume we want 2mA through those resistors.
With a 530V rail you have 265V across each cap.
Resistors calcuated as 265V/2mA = 132KOhms (maximum value)
I would strongly suggest you revert to 120K resistors across the caps.
Power Dissipated in each resistor = V squared on R:
R
= (265)^2 / 120K
= 0.585 Watts
Use 2W metal films, 3W metal oxide, or 5W wire wound.
Submitted and edited by SyncTroniX for use here.
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