STATIC TRANSFER SWITCH (STS)

Static Transfer Switch is a three phase, six pole semiconducter power switch, which can switch between tosyncronious AC sources without interrupting the output power less than ¼ cycle. Because it is fully static, itdoesn’t have any moving parts like fans and relays, and can transfer the power via thyristors.The primary task of a Static Transfer switch is to continiously supply the output with uninterrupted energy,even when one of the feeding input sources fails. One source of the Static Transfer Switch is called aspreferred source, where the other source is called as alternate. Supplying the output through the preferredsource has the priority, it means, if bout sources are available and withing acceptable limits, preferred sourcewill be chosen. If any problem is detected on the preffered source, the load is transferred to the alternatesource within less than ¼ cycle. It is adjustable, which source is designated as preferred and which isalternate.There source be no back-feed during the supply of the load, it means, in any transfer, sources should not beallowed to clash. Otherwise, it is possible that both sources will be unavailable. (example, shorting outputs oftwo independent operating UPS’s)

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