Capacitor fuse overview — Capacitor fuse terminology An ideal fuse could be defined as a lossless smart switch that can thermally carry infinite continuous current, detect a preset change in the continuous current and open automatically (instantly) to interrupt infinite fault currents at infinite voltages without generating transients.
How do you choose a capacitor fuse?
The fuse protecting the capacitor is chosen such that its continuous current capability is equal to or greater than 135% of rated capacitor current for grounded-wye connected racks, and 125% for ungrounded-wye racks. This overrating includes the effects of overvoltage, capacitor tolerance, and harmonics.
Are capacitor fuses capacitive limited?
Most capacitor fuses have a maximum power frequency fault current that they can interrupt. These currents may be different for inductive and capacitively limited faults. For ungrounded or multi-series group banks, the faults are capacitive limited.
What is a capacitor fusing factor?
The capacitor must be able to absorb this energy with a low probability of case rupture. Fuses are usually applied with some continuous current margin. The margin is typically in the range of 1.3 to 1.65 per unit. This margin is called the fusing factor.
The CIL current-limiting capacitor fuse has a two-part design. The high current section interrupts high 60 Hz fault currents and/or high frequency discharge current from parallel capacitors. The low voltage section consists of a standard NEMA Type K fuse link mounted in a fiber tube.
What is an ideal fuse?
An ideal fuse could be defined as a lossless smart switch that can thermally carry infinite continuous current, detect a preset change in the continuous current and open automatically (instantly) to interrupt infinite fault currents at infinite voltages without generating transients.
Either of these two effects can impede the proper operation of the fuse. In the event of a capacitor fault, excess current will flow through the fuse of the faulted unit. This current causes the fuse element to melt and vaporize. An arc will form across the vaporized section within the fuse tube.