Undervoltage Thresholds

Default value

• Dropout: 10%

• Pickup: 20% of delta dropout

Range

Delta voltage ranges from 4%–20% of rated voltage: It could be 4–6–8–10–12–14–16–18–20%.

Differential

The differential between dropout and pickup on automatic HMI is fixed. The differential is set at 20% of the delta value.

Sequence of events

• When a sensor detects a voltage below the dropout set voltage for a period longer than the time delay, it will deem the voltage for out of range.

• When a sensor detects a voltage at or above the pickup point, it will deem the voltage as acceptable.

Example of calculation on undervoltage of TransferPacT Automatic

For example, Ue= 400 V , Dropout 10%= 40 V,

Differential between dropout and pickup= 40 V * 20%= 8 V

Undervoltage dropout is 400 V - 40 V= 360 V

Pickup= 360 V + 8 V= 368 V