9424200996 84-45
BE1-11m Settings Calculation Examples
Figure 84-57. Protection, Current, Instantaneous Undercurrent (37) Screen
Protection - Voltage
Two undervoltage protection elements are used to monitor undervoltage conditions.
Undervoltage (27P-1) Sag
When the motor is running, undervoltage conditions can jeopardize production (motor speed), cause the
synchronous motor to slip a pole, or affect electronic and 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 84-41.
= 90%
1
= 0.90 12,000
1
100
= 108
Equation 84-41. 27P-1 Pickup
There is no need to set the Inhibit Level because the element is active only during the running mode as
shown in the logic, Figure 84-69.
Select Three of Three mode, set the Pickup setting to 108 Secondary V. The delay should be set as short
as possible, and longer than the start time of other motors on the bus. Because there are no other motors
in this example, set the Time Delay to 100 ms as shown in Figure 84-58.
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