9424200996 84-17
BE1-11m Settings Calculation Examples
Starting Slope
The BE1-11m considers the motor to be starting when current is greater than 2 • FLA in any phase. The
starting mode ends when current in all three phases drops below 2 • FLA. Therefore, the 2
nd
Slope
Pickup (starting) should be set at the point that restraint current is 2 • FLA where motor torques and
heating settle quickly to running mode currents (as observed in typical time-current curves). With
Restraint Slope 1 % (running) set to 15%, Iop for Restraint Slope 2 pickup should be 15 percent of
restraint current. See Equation 84-13.
2 =
2 = 4.54 2 = 9.08
2 =
9.08
2.0
= 4.54
Equation 84-13. 2
nd
Slope (Starting) Pickup Setting
Figure 84-21 shows an example of 2
nd
Slope Restrained Operation.
Based upon good engineering practices during starting mode to overcome dc offset and CT mismatches,
set Restraint Slope 2 % at 1.7 times the running mode slope and add a 25 percent margin. Restraint
Slope 2 % is calculated using Equation 84-14.
2 % = 1.7 1.25 15% = 32%
Equation 84-14. Restraint Slope 2 %
Set the 2
nd
Slope Pickup (starting) at 4.54 and the Restraint Slope 2 % at 32.
Figure 84-21. 2
nd
Slope Restrained Operation Example
Alarm
The BE1-11m provides a Slope % alarm for cases where high loads or through faults cause unbalance in
the differential. The Slope % Alarm is calculated in Equation 84-15.
% = 1.5 2 % = 1.5 32% = 48%
Equation 84-15. Slope % Alarm
The setting range for Slope % Alarm is 50 to 100 in increments of 1, so a Slope % Alarm of 50% is used
for this example.
The Current Differential (87) screen is shown in Figure 84-22.
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