Powerware 9335 operation manual Bypass Mode, Static Bypass

5.2.2 Bypass Mode

The UPS automatically switches to Bypass mode if it detects an overload, load fault, or internal failure. The bypass source supplies the commercial AC power to the load directly.

Figure 5–3 shows the path of electrical power through the UPS system when operating in the Bypass mode.

CAUTION:

The critical load is not protected while the UPS is in the Bypass mode.

Static Bypass

Figure 5–3. Path of Current Through the UPS in Bypass Mode

In BYPASS mode, the output of the system is provided with three phase AC power directly from the systems input. While in this mode, the output of the system is not protected from voltage or frequency fluctuations or power outages from the source. Some power line filtering and spike protection is provided to the load but no active power conditioning or battery support is available to the output of the system in the bypass mode of operation.

The internal bypass is comprised of a solid state silicon controlled rectifier (SCR) static switch (SSW), and a back feed protection contactor (K4). The static switch is rated as a continuous duty device that is used anytime the boost converter and inverter is unable to support the applied load. The static switch is wired in series with the back feed protection