Connecting new generators to the electricity supply system causes the fault level to increase locally because generators produce high currents when there is a short-circuit in the vicinity. This can cause the system fault level to rise beyond the fault current withstand capability of network components (switchgear, cables etc.).
Fault Current Limiters restrict the fault level contribution from Distributed Generation. Their use allows the safe, quick and cost effective connection of renewable energy sources and the resulting reduction in CO² emissions.
They provide a new and radically improved alternative to:
- Splitting the network, which requires complex control strategies and reduces quality and security of supply and network efficiency.
- Installation of series reactors or transformers to increase system impedance. These cause permanently increased losses and are detrimental to power quality.
- Switchgear or board replacement is an expensive and a complex process that takes considerable time and space. It requires space for the new switchgear so that it can be installed and commissioned while the old equipment remains in service. Only then can the old switchgear be de-commissioned and the new connected. This space is not always available and can, in urban areas, be very expensive. This process, including civil work and possibly requiring planning approval can take years resulting in new generators queuing to be connected. Such delays and the associated costs can render the generation developers' business plans void.
Additionally and often more critically, replacing the switchgear does not reduce the fault level. Network Operators generally specify a fault level maximum so that private network owners are protected from the network fault contribution rising unexpectedly and threatening their equipment, so the conventional solution to rising fault level has been to split the network or to fit reactors or high-impedance transformers.