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Bypass settings of Single Phase Symmetra UPS systems

Published date: 17 February 2021

Issue:
What are the different bypass settings of a single phase Symmetra UPS?

Product Line:
Symmetra Power Array
Symmetra RM
Symmetra LX

Environment:
All serial ranges

Resolution:
The Bypass setting is used to adjust the automatic bypass controlled by the intelligence modules and can be accessed via the PowerView under the Settings menu. This setting will dictate how the UPS will react to issues that prevent it from operating online, such as becoming overloaded. Should the UPS encounter this type of issue where it can no longer support the equipment, the UPS can react in 1 of 2 ways:

1) Go to bypass
2) Drop load

When the UPS is set to "Go to Bypass" the bypass operating range is at its widest: -20% to +10% of the phase-phase output voltage. For instance, if the output is set to 208 volts (adjusted from the Settings menu) then the bypass operation will function with an input voltage range of 167-229 volts. 

When the UPS is set to "Drop Load" the bypass operating range is narrow: -12% to +6% of the phase-phase output voltage.  

Once the UPS is in automatic bypass it will support the load as long as the input voltage stays within +/-25% of the output voltage selected. 

When commanded into bypass via the PowerView or an accessory, the UPS will use the narrow range of -12% to +6%, or the output frequency is not synchronized to the input, the UPS will not allow itself to be commanded to bypass if it is currently operating on-line. 

Keep in mind that, when absolutely necessary, the UPS can still be forced into maintenance bypass via the breaker on the UPS. If the UPS does not allow itself to be commanded into bypass via the PowerView or any other accessory, damage to connected sensitive loads may result by forcing bypass via the maintenance bypass switch due to the difference between the output voltage from the inverters and the input voltage from utility. For example, a load being fed 208 volts from the inverters while the input voltage is 260 volts will introduce the load to a sudden voltage increase if bypass is forced using the maintenance bypass switch. 
For these reasons it is important that the output voltage from the UPS matches the input voltage. 

 


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