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 mΩ 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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