Double fuse structure capacitor
Each capacitor element has a fuse inside the capacitor element. The fuse is a basic part of the wire sufficient to limit the current and capsulized in a wrapper that can resist the heat generated by the arc. Upon a capacitor element fault, the fuse takes out the struck element only.
What is the function of fuses in a shunt capacitor bank?
The function of fuses for protection of the shunt capacitor elements and their location (inside the capacitor unit on each element or outside the unit) is a significant topic in the design of shunt capacitor banks. They also impact the failure modality of the capacitor element and impact the setting of the capacitor bank protection.
What is a capacitor bank protection fuse?
related to the starting of the motor defined in IEC 60644. The capacitor bank protection fuse-links are described in IEC 60549 (High-voltage fuses for the external protection of shunt capacitors) . Also in this case the fuse should meet the requirements described in the general standard IEC 6028
How does a capacitor fault affect a fuse?
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.
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.
What is a high voltage capacitor fuse?
For high voltage capacitor fuses, this is generally defined as 8.3, 15.5 or 23 kV, the distribution system maximum voltages. Other voltage ratings may be available for special applications. When a capacitor fails, the energy stored in its series group of capacitors is available to dump into the combination of the failed capacitor and fuse.
How do capacitor current limiting fuses work?
Capacitor current-limiting fuses can be designed to operate in two different ways. The COL fuse uses ribbons with a non-uniform cross section. This configuration allows the fuse to be used to interrupt inductively limited faults. The pressure is generated by the arc contained in the sealed housing.
