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Registered Member #152
Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384
I have 400VDC PP (polypropylen) caps, that can be charged to 1000V, and they take the charge for long time, without failure. I'm not sure about polyester though, but I think they should be able to withstand it.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
A 275 Vac rating means AT LEAST sqrt(2) x 275 = 389 V peak In practice the capacitor will probably be 400 to 600 V dc rated. Capacitors are tested to 1.5 to 2.2 times rated so for UNSAFE use up to 1000 V probably works.
Registered Member #89
Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145
Poliesters know to be sensitive, you can easily get fireworks on your bridge. They may work but it is not good idea. For even pulsed operation I dont recommend them, rather series two and be 100% safe. I blew easily some poliesters discharging them rapidly at 300V rated for 400, so I dont recommend pushing twice or more rated voltage.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3141
For ac bypassing of the dc supply to the bridge I would put all in parallel to reduce the current in each
from memory, I have destroyed mylar capacitors through overheating either high frequency dielectric dissipation or Isquared.R Mylar film caps seem quite good with overvolting. I use polypropylene capacitors for ac bypass of the dc supply (because I have them) Motor-run and film/foil.
Good Aluminium electrolytics seem ok below 100 kHz, and above that Mylar gets really lossy.
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Over-rating metalised polyester caps
