9424200996 84-19
BE1-11m Settings Calculation Examples
Undervoltage (27P-1)
When the motor is running, undervoltage conditions can jeopardize production (motor speed) or affect
electronic or digital controls. When running voltage dips occur, the motor should be disconnected quickly.
Set the 27P-1 protection element active in running mode only for 90 percent per the NEMA MG-1
standard. A delay of 100 ms will ride through fast voltage transients and prevent false tripping. The pickup
setting is calculated in Equation 84-17.
= 90% = 0.90 120 = 108
Equation 84-17. 27P-1 Pickup
Select Three of Three mode, set the Pickup setting to 108 Secondary V, and set the Time Delay to 100
ms as shown in Figure 84-24.
Figure 84-24. Protection, Voltage, Undervoltage (27P-1) Screen
Undervoltage (27P-2)
The 27P-2 protection element is set to trip when source voltage is too low for a successful start. The
motor manufacturer data indicates that the minimum voltage for a successful start is 85 percent of
nominal. The 27P-2 element is set to prohibit starting when voltage is below 70 percent of nominal. The
pickup setting is calculated in Equation 84-18.
= 70% = 0.70 120 = 84
Equation 84-18. 27P-2 Pickup
Select Three of Three mode, set the Pickup setting to 84 Secondary V, and set the Time Delay to 0 ms as
shown in Figure 84-25.
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