What is capacitor inrush current?
Inrush current is the instantaneous high input current drawn by a power supply or electrical equipment at turn-on. This arises due to the high initial currents required to charge the capacitors and inductors or transformers. The inrush current is also known as the switch–on surge, or the input surge current.
Why capacitor inrush current is abnormally high?
During power-on, a high inrush current can occur because the power supply’s link capacitor functions to dampen ripples in the output current. This capacitor acts like a short, causing an inrush of current. The low internal resistance of the power supply aggravates this issue.
What happens when a decoupling capacitor is connected?
As almost all circuits have decoupling capacitors, when a power source is connected there will be an inrush current. This current can be very high, causing temporary heating in the capacitor and possible damage to switch contacts or components connected in series.
How to calculate the maximum inrush current of a capacitor?
For turn-on cases, there is only one event, and that will not build up enough heat to damage the component, unless something really esoteric is going on. You can calculate inrush current easily; divide input voltage by ESR of the capacitor; this is the maximum inrush current right at the start.
What are the devices that limit the inrush current?
It consists of sensitive components that switch high incoming current. Some of the active devices are Soft Starters, voltage regulators, and DC/DC converters. These protections are used to protect the electrical as well as a mechanical system by limiting the instantaneous inrush current.
Can a tantalum capacitor withstand a Max Voltage?
Tantalums are notorious for becoming seriously damaged even when a max. voltage or current rating is violated only once, and only just briefly. Example application guideline from AVX, KEMET and others will likely give you similar information: The solid Tantalum and OxiCap® capacitors have a limited ability to withstand voltage and current surges.