A static bypass switch automatically and instantaneously transfers the load to the mains electricity supply when there’s an internal fault or failure with the UPS system.
It is a common characteristic of an online UPS. In effect, running on bypasses the UPS circumvents (i.e., rectifier, batteries, and inverter) and ensures power continuity while the UPS is fixed or swapped out.
This is known as a ‘safe failure to mains’ and occurs for various reasons, such as a fault within the UPS or an overload (short-circuit). Once the fault is cleared, the bypass automatically transfers the load back to the UPS.
However, operating on bypass does not filter or condition the input or output supply as with typical double conversion online UPS systems, so should be used sparingly.
Internal static bypass switches should not be confused with external maintenance bypass switches. This is an option that enables the UPS to be powered down manually for maintenance while the critical load is powered directly from the mains.
External maintenance bypass switches tend to be mechanical in the form of a wraparound or rotary switch or a set of circuit breakers.
Line Interactive and Offline UPS systems do not typically incorporate internal automatic bypasses. An alternative solution is to install an external maintenance bypass with an automated transfer feature. This automatically transfers the load to the mains if the UPS fails.
Examples Of Static and Maintenance Bypass in A UPS System
Static Bypass Mode:
The UPS supplies the load with power from the bypass source. If the conditions for normal or battery mode are not met, the load will be transferred from the inverter to the bypass source with no interruption in power to the load.
It is a common characteristic of an online UPS. In effect, running on bypasses the UPS circumvents (i.e., rectifier, batteries, and inverter) and ensures power continuity while the UPS is fixed or swapped out.
This is known as a ‘safe failure to mains’ and occurs for various reasons, such as a fault within the UPS or an overload (short-circuit). Once the fault is cleared, the bypass automatically transfers the load back to the UPS.
However, operating on bypass does not filter or condition the input or output supply as with typical double conversion online UPS systems, so should be used sparingly.
Internal static bypass switches should not be confused with external maintenance bypass switches. This is an option that enables the UPS to be powered down manually for maintenance while the critical load is powered directly from the mains.
External maintenance bypass switches tend to be mechanical in the form of a wraparound or rotary switch or a set of circuit breakers.
Line Interactive and Offline UPS systems do not typically incorporate internal automatic bypasses. An alternative solution is to install an external maintenance bypass with an automated transfer feature. This automatically transfers the load to the mains if the UPS fails.
Examples Of Static and Maintenance Bypass in A UPS System
Static Bypass Mode:
The UPS supplies the load with power from the bypass source. If the conditions for normal or battery mode are not met, the load will be transferred from the inverter to the bypass source with no interruption in power to the load.
Maintenance Bypass Mode:
In maintenance bypass mode, the mains are sent via the external MBB to the load. Battery backup is not available in maintenance bypass mode.
Released for:Schneider Electric India
