Voltage Sag

Voltage sag is a sharp reduction in the supply voltage to a value between 90% and 1% of the nominal voltage, followed by the restoration of the voltage after a short period of time.

The following table details the different values of sag percentage that define the system.

Value	Equipment parameter
s1	Lower limit of continuous regulation
s2	Maximum sags without voltage alteration
s3	Maximum sag without static bypass

The following table shows the function of PowerLogic™ DVR system for the corresponding voltage sag value.

Voltage sag value	Function of PowerLogic™ DVR system
≤ s1	Permanently compensates the disturbances up to ≤ s1 value and obtains a nominal output voltage of ±1%.
Between s1 and s2	Compensates and obtains an output voltage of ±1% of the nominal voltage. NOTE: The system operation against this sag range with a duration of 30 seconds is guaranteed.
Between s2 and s3	Compensates gradually altering the output voltage depending on the depth of the sag. If the sag is 5% greater than s2, the output voltage will be 95% of the nominal voltage. If the sag is 10% greater than s2, the output voltage will be 90% of the nominal voltage. NOTE: The system operation against this sag range with a duration of < 1 second is guaranteed, if no upstream protection of the PowerLogic™ DVR system or the impedance of the network prevents it.
>s3	PowerLogic™ DVR system switches to Static Bypass mode and obtains an output voltage the same as the input voltage.

The following image details the 3-phase compensation capacity of PowerLogic™ DVR system.

The PowerLogic™ DVR system eliminates 3-phase, 2-phase, and 1-phase voltage sags, since it compensates the each phase independently. The following graph shows an example of PowerLogic™ DVR system operation where sudden drop in the input voltage (green line) is compensated to stable output voltage (blue line).