B59404 PTC Thermistor TDK B59404 PTC Thermistor is designed for DC voltages of up to 500V and AC voltages of up to 350V. This thermistor self-protects in case of an internal short circuit of the capacitor or malfunction of the short-circuit relay. The B59404 thermistor can switch off a defect (short circuit) up to 100 times and up to 100,000 cycles when charging and discharging capacitors. This thermistor features 500Ω rated resistance, 500VDC maximum link voltage, 1J/K typical heat capacity, and ±30% resistance tolerance. The B59404 thermistor operates from -40°C to +125°C temperature range and at 350VAC maximum voltage.