Automatic Bypass. ABB TLE Scalable UL Series UPS

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4.2.5

Automatic Bypass

TLE Scalable Series 40 to 150 UL S1 UPS User Manual / REV-B

In normal operation, the Load is supplied by the Inverter.

When the control system detects a fault in the

Inverter, an overload condition or a shortcircuit condition, the Automatic Bypass will transfer the critical Load to the Utility without interruption.

When the Inverter recovers, or the overload or short-circuit condition is corrected, the Load will be automatically transferred back to the

Inverter.

Fig. 4.2.5-1 Block diagram Automatic Bypass

If the UPS is unable to return to normal mode following an automatic transfer to Bypass mode, an alarm condition will be initiated.

In case of RPA Parallel System

Each Unit has its own internal Bypass.

These Units are continuously exchanging information, enabling all of the internal Bypass circuits in an RPA Parallel

System to operate simultaneously.

If the Inverter of a Unit fails, its Bypass circuit remains available to the RPA Parallel System.

It is excluded only if the Unit is separated from the common bus by opening its “Q1 – UPS output switch”.