| Some electrical utilities and manufacturers go one step further than just depending on warning signs to draw attention to high voltage hazards near electrical installations.
With a permanently mounted live line indicator, the end-users are instantly warned that a particular part of their high voltage installation is energised and under power. The fixed mounted high voltage indicators are protective safety devices that will indicate the status of the electrical distribution system to the worker, maintenance personnel or inspectors. When approaching an electrical installation, either in an open area with indoor protection or in an indoor/outdoor switchgear apparatus, the most effective and inexpensive method is to provide the electrical installation with a permanently mounted single pole voltage indicator.
These voltage indicators, also called live line indicators, can be viewed at a safe distance in open areas and/or through viewing windows installed within the switchgear assembly. The indicators are permanently installed by the switchgear manufacturer upon specification and in the desired locations throughout the assembly, as requested by the owners. The most practical place to install them would be at the incoming voltage supply lines or at the outgoing side of a load break switch with or without fuses or in similar arrangements where the indication of the system status would be desired.
The advantage of having such single pole voltage indicators mounted within the switchgear assembly is to give the end-user a quick and instant warning about the status of the electrical installation without having to open locked doors and to be exposed to electrical hazards. This efficient method can be achieved by viewing the voltage indicators from the outside of the switchtear assembly through a reinforced glass window. Also, there is no need for special tooling or measuring devices to search or test for blown fuses.
The permanently mounted live line indicators will indicate when a conductor or circuit is energised. The live line indicators do not require any settings or adjustments. They are dielectrically insulated and will not generate any flashover during a hi-pot or corona discharge test.
These voltage indicators are rated and factory set from 2 kV to 46 kV and another type from 69 kV to 138 kV. They are designed for bolt and nut connection with a flexible cable lead that will maintain its position in any chosen bending angle for perfect visibility of the flashing LEDs. Another connecting method can be with a stud type connection. In both cases, the indicators must make direct contact with a bare electrical surface or connecting point.
The history of voltage indicators can be traced back to fifteen years of dependable performances. They are of extra light design with a physical size of only 1.5 x 5.5 inches for the flexible cable type and 2" x 2" for the stud mounted type.
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