LV generator protection - engineering site - Schneider Electric
LV generator protection - engineering site - Schneider Electric
LV generator protection - engineering site - Schneider Electric
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In shortReplacement Set or Safety Set.The same functions are required:ensure continuity of the electricalsupply should the main source fail.However, a Safety Set must satisfyfar more exacting operatingrequirements in order to guaranteesafety of the electrical installation atall costs.The Generator Set and<strong>Electric</strong>al Distribution1.2.Quality EnergyTo supply sensitive loads (computer, etc.), a quality energy must be implementedthat is free from breaking and with a perfectly regulated voltage.A number of systems can be used to ensure break-free switching. Thesesystems are implemented in the <strong>LV</strong> system:b reversible synchronous machinethe Set <strong>generator</strong> is permanently connected to the mains supply:v when operating in the Main function, it operates as a synchronous motor drivingits inertia flywheelv when operating in the Replacement function. When the Mains supply fails, thesynchronous machine, driven by its flywheel, starts to operate as a <strong>generator</strong>.The Set’s thermal motor starts (off-load) and automatically connects as soon as itreaches its speed at the <strong>generator</strong>.When the Main source is restored, the Set is then synchronised on the Mainsource, the Main source circuit-breaker closes and the thermal motor isdisengaged and stopped.E79357E<strong>Electric</strong>al utility networkSNmainsourceSynchronousmachine(compensatoror <strong>generator</strong>)MagneticcouplingFlywheelThermalmotorNCNCNon-backed upfeedersBacked upfeedersNC: normally closed.NO: normally open.Figure 5: Block diagram of a reversible synchronous machine.This type of solution is not very common as it is relatively expensive toimplement.b <strong>generator</strong> Set associated with a UPSthe <strong>generator</strong> set ensures continuity of the electrical supply. <strong>Electric</strong>al supplyinvolves breaking (from a few minutes to a few seconds). Energy Quality(elimination of outages/brownouts and waveform) is obtained by anUninterruptible Power Supply (UPS) - equipped with a battery- which continuallysupplies sensitive loads in <strong>LV</strong>.This type of solution is advantageous as it provides sensitive loads with qualityenergy during use on a Main or Replacement source.8