Basler Electric BE1-851 - Manual (Page 63)

group three return timer begins timing. Current varies but stays below 75 percent for 5 minutes and at
time = 75, setting group two becomes active and the setting change output pulses. After 20 minutes,
setting group zero becomes active and the setting change output pulses.
Figure 4-6. Automatic Operation Based on Load Change
This function can also be used to automatically change the active setting group for cold load pickup
conditions. If the switch to threshold for a group is set to 0%, the function will switch to that group when
there is no current flow for the time delay period indicating that the breaker is open or the circuit source is
out of service. The threshold for this is 10% nominal rating of the relay current input.
Figure 4-8 shows how the active setting group follows the load current and time delay settings. Figure 4-7
illustrates the operating settings used in the diagram shown in Figure 4-8. Note that the AUTO input must
be at a TRUE (1) logic state for the automatic logic to operate. When the breaker opens, the load current
falls to zero, time = 15 minutes. After 10 minutes, setting group one becomes active and the setting group
change output pulses TRUE. When the breaker is closed, time = 40 minutes, load current increases to
approximately 90 percent of pickup. As the load current decreases to 50 percent of pickup, the setting
group one return timer begins timing. After ten minutes, setting group one output goes FALSE, the setting
group returns to setting group zero, and the setting group change output pulses TRUE.
When the switch to criteria is met for more than one setting group at a time, the function will use the
numerically higher of the enabled setting groups. If the switch to time delay setting is set to 0 for a setting
group, automatic control for that group is disabled. If the return time delay setting is set to 0 for a setting
group, automatic return for that group is disabled and the relay will remain in that setting group until
returned manually by logic override control.
9289900990 Rev R BE1-851 Protection and Control 4-7