Pulse Capacitor vs other Capacitors?

[gary350]

What makes a pulse capacitor different than other capacitors?

I know from experience with tesls coils ceramic capacitors have a 65% power loss.

I know from tesla coil experience that a .1uf flat plate capacitors produces 2 times more power output than a .1uf rolled capacitor.

So I wonder, what makes a pulse capacitor be a pulse capacitor?

 

[MikeMl]

ESR, and possibly parasitic inductance.

 

[shortbus=]

From research for one of my projects, an EDM power supply, I found that the big difference is they are self healing. By that it means if they arc through the dielectric the dielectric reforms as the arced spot cools down. You do also know to chose a voltage rating of around two times the circuit voltage, right?

 

[ronsimpson]

What makes a pulse capacitor different than other capacitors?

A capacitor used for timing probably has uA of flow.
A filter cap might have mA flow.
Resonant capacitors (flyback and and S-correction caps see amps)

Tesla coils capacitors (TV flyback capacitors) are rated for high current. Generally a pulse capacitor has much more data and graphs on the data sheet. I use capacitors rated at 10A and 1600V. There is data as to what duty cycle the current can be at.

With a resistor you can look at its size and get an idea for 10 watt or 1/4 watt. By looking at the lead size you can tell that a 1/4W resistor will never take 10A for long. With a capacitor it is not so clear. Much of what makes a high current capacitor is hidden deep inside.

Generally a capacitor should not get hot or even warm. It it is warming you are not using the part correct.

 

[jpanhalt]

Another factor to consider is that the leads on capacitors are made of steel and ohmic heating can be an issue. I used screw connections to aluminum terminals.

John

 

[ronsimpson]

Here is a pulse cap.
https://www.wima.com/EN/mkp10.htm
I can't find the application note for use of these caps. If you really need it I can look some more.

 

[nsaspook]

Some applications of 'pulse' capacitors.
https://www.ga.com/pulse-forming-networks

 

[Flyback]

I believe polypropylene caps are the kings of pulse handling.
Inevitably, those capacitors that are best at handling pulses also are large in volume compared to their capacitance..unfortunately.

When I worked at a xenon warning beacon company, we had 22uF electrolytics which were charged up repeatedly, and then discharged by the xenon tube flash...the xenons flashed once per 500ms, and the flash current was about 24 Amps for 200us...this all came from the electrolytics, and 3000 beacons blew up their electrolytics with in the frst three months.....bad news....that place is now closed down. You could see the 'lytics all blown up when you opened them up.