Why we are using static bypass in ups?

A static bypass is fitted to almost all On-line UPS; it forms the second line of defence. Should the inverter fail, the static bypass ensures the load drops automatically onto the mains input feed.

With an On-line UPS, if an inverter fails, it will, in all probability, occur whilst mains power is present.

Static Bypass switches are used to bypass the UPS normal operation, in cases of high inrush or fault conditions,these operations to be performed without loss of power to the load. 

A second level of defense on the UPS. When we got any failure -mainly on the inverter- all OnLine UPS must transfer to the ByPass mode.

Also, when the UPS got an inrush current, the UPS will apply the same mechanism. 

UPS needs a static bypass either internal or external bypass as UPS is an uninterrupted power source,whenever there is a fault in the inverter section of the ups and the UPS could not supply the load, it should go to the bypass mode without dropping the load.