Capacitors are energy-storing devices. They store energy into an electric field and their basic function is to add capacitance to an electric circuit. To do so, they badly need resistors: both for charging and discharging.
For charging a capacitor bank, a resistor is needed because the high inrush current can seriously damage the semiconductors, along with other elements. Therefore, by limiting the current flowing into the capacitor, the resistor not only protects these elements. It also prevents overvoltage, which can result in the breakdown of the capacitor and in serious damages to other elements connected to the circuit.
In order to safely discharge a capacitor, resistors are equally needed, because capacitors discharge almost instantly without them. With high voltages, this is very dangerous in that it can result in sparks and fire. Resistors are the most common and the most efficient solution to prevent this from happening.
Capacitors are virtually ubiquitous in today’s electronics. Their size and voltages depend on the devices and circuits they feature in. At the industrial level, large high voltage capacitors banks can be found, and they need special resistors for charging and discharging safely. Some of the most common applications of this kind of capacitors are:
Uninterruptible power supply (UPS) systems
Pulsed lasers (especially TEA)
Power supply networks, as suppressors of undesirable frequencies (e.g., glitch removal on Direct Current power rails)
FAIRFILD’S RESISTORS FOR CHARGING AND DISCHARGING CAPACITORS
Over the years, Fairfild designed several custom snubber resistors, as well as many series and models perfectly suited for working in tandem with capacitors.