can also distinguish permanent faults from transient faults. Some modern network protection systems e.g. GFN have time to clear a fault as small as possible down to 60ms so fault indicators must not only be highly sensitive and directional but additionally very fast. Modern fault indicators can detect faults with the duration of one cycle 18-20 ms. In the networks with low earth fault levels the indicators are required to be set to low values. In such cases the user should consider the downstream capacitive discharge current to avoid false operation of the non-directional indicators. Some overhead line fault indicators called as pole mounted fault indicators can detect the live line and the fault current from 3 to 5 meters below the conductors. High-voltage fuses commonly drop down after operating, making it obvious where the fault is. However fuses are rarely equipped with remote communication. History The first fault indicators came onto the market from Horstmann (Germany) in 1946. The E.O. Schweitzer Manufacturing Company (now a division of Schweitzer Engineering Laboratories, Inc.) introduced a product to the United States in 1948. The first fault indicators were manual reset devices. Later fault indicators automatically reset on system restoration or after a set period of time. More recent fault indicators communicate their status (tripped or reset) via cell signal or radio to a central station, handheld device, or pole-mounted receiver. Recent developments include a remotely programmable overhead line indicator, fault indication for paper-insulated lead cable, and an overhead fault indicator for mesh networks. See also Power transmission Polyphase system Electricity distribution Overhead powerline Power outage Three-phase electric power Electric power distribution Electrical components