Fault Current Limiting Devices

This is another way of saying use a series rated system.

Fault current limiting devices.

The growing energy demand and the need for stable power supply are some of the major challenges faced by consumers power producers and network operators. The load side fault level is the same as the line side fault level or any other value lower than the calculated ohm s law prospective fault current. This can be determined through testing known as series rating but is not permitted for consideration within ul 508a. A fault current limiter fcl also known as fault current controller fcc is a device which limits the prospective fault current when a fault occurs e g.

The term includes superconducting solid state and inductive devices. Do not assume the fault level downstream of current limiting devices is 6ka it isn t. Fault current limiters fcls are special power system devices used to mitigate and lower high short circuit currents to much more manageable levels for existing protection equipment like circuit breakers cbs. This fault current limiter was installed in uk power network s 33 11 kv substation in newhaven east sussex england in 2013.

Use a current limiting overcurrent protective device ahead of the old switchboard. During normal operation a continuous current flows through the reactor. The most common applications are the connection of two independent systems bypassing or replacing of a current limiting reactor and connecting additional power sources ie generator or grid connection. Current limiting reactors are connected in series with the power system essentially to damp the short circuit fault current.

It is unknown how the downstream overcurrent protective device will perform in conditions where the fault current exceeds its interrupting rating even in conditions where a current limiting feeder is applied. The i s limiter can be used in various applications providing a very high and fast fault current breaking capability at high operating currents. The fcl enables the substation to run with all three 33 11 kv transformers connected to the 11 kv bus bars with a fault level of 11 3 ka. You check the equivalent rms let through current of a 1200a class l fuse and find it reduces the 45 119a available down to 21 000a.

Fault current limiting abb s fault current limiters are the efficient solution for short circuit current challenges in newly installed and existing electrical networks.