84-44 9424200996
Settings Calculation Examples BE1-11m
Figure 84-56. Protection, Current, Current Differential (87) Screen
User Programmable Alarm
User Programmable Alarm 3 is used for reporting a minor alarm, which indicates a large percentage
restraint imbalance during starting mode. Use the Settings Explorer to navigate to Alarm Configuration,
User Programmable Alarms, and name User Programmable Alarm 3 to “Differential Slope”. Navigate to
Alarm Configuration, Alarms, and enable Programmable Alarm 3 as a minor alarm. This alarm will appear
in the sequence of events and alarm reporting as “Differential Slope”.
Instantaneous Undercurrent (37) - Loss of Load Protection
The 37 element protects the motor from overheating by tripping when a load or shaft coupling is lost and
motor current drops. The 37 element protects only when the motor is in running mode and can be set to
trip on a loss of load condition, especially for pump motors where flowing water cools the motor. For
pumps, a loss of current would indicate less cooling. The pickup setting is calculated in Equation 84-39.
= 75%
1
= 0.75 205
1
60
= 2.563
Equation 84-39. 37 Pickup
The Inhibit Level is a low-level setting for when the motor is off and a nuisance trip or alarm is not desired.
Set this setting to 20 percent of FLA as calculated in Equation 84-40.
= 20%
1
= 0.20 205
1
60
= 0.683
Equation 84-40. 37 Inhibit Level
Select three-phase mode, set the Pickup setting to 2.563 Secondary A, the Inhibit Level to 0.683, and set
the Time Delay to 100 ms (to override load changes) as shown in Figure 84-57.
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