Good MMC capacitors

Here is a list of capacitors tested by the high voltage community to be known to withhold the use as primary capacitor in Tesla coils.

Capacitor specifications are taken from data sheets at 100kHz and some values for peak current, rms current, ESR and dv/dt are estimates(* marked) from similar capacitors and graph read outs.

Product Ipeak Irms ESR dV/dT Rth
data sheet V μF A A V/μS °C/W
Aerovox RBPS20591KR6G 1000 2 854 22 7 427 15*
CDE
942C20P15K-F
2000 0.15 432 13.5 5 2879 11
CDE
940C20P1K-F
2000 0.1 171 8.3 7 1712 11
EFD SP
2550-2
1000 3.75 2500* 152 1 810* 10*
Kemet
R474N247000A1K
900 0.047 28 4* 135 600 51
Kemet
R76UR3150SE30K
2000 0.15 345 10 26 2300 23
Panasonic
ECWH16333
1600 0.033 198 3.5 350* 6000 40
Panasonic
ECWH16473
1600 0.047 282 4.3 250* 6000 40
Panasonic
ECWH16563
1600 0.056 333 5 150* 6000 40
TPC
CMPPX4K0K0405
3000 4 5000 80* 0.75 1250 6.9
WIMA
FKP1O131007C00
1000 0.1 1100 6 10 11000 33
WIMA
FKP1T031007E00
1600 0.1 1100 6 10 11000 33
WIMA
FKP1R032207F00
1250 0.22 2420 6 9 11000 33

Capacitive reactance Xc = 1 / ( 2 * π * f * C)

ESR can be calculated from the tangent of loss angle given as TANδ in the data sheets. ESR is frequency dependant. Capacitance is given in Farad, frequency in Hertz. ESR = (1 / (2 * π * f * C)) * TANδ = TANδ * Xc.

Thermal resistance (Rth) when given in data sheets are either Watt needed to raise the temperature by one Kelvin or degree Celsius the temperature raises by one Watt dissipation. Conversion from W/K to °C/W is to divide one by W/K dissipation factor.  °C/W = 1 / (W/K).

Ipeak is calculated from the dV/dT rating times the capacitance of the capacitor. Capacitance given in micro Farad times pulse rise time given in micro seconds will give a result in Ampere. Ipeak or Ipulse = C * dV/dT.

As a rule of thumb ESL is about 1.6 nH per millimetre of lead distance between the capacitor itself and the rest of the circuit. This also includes the leads of the capacitor itself. This only applies to well designed capacitors.

 

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