Advantages, Specifications, Time overcurrent (51) element – Basler Electric BE1-50/51B-244 User Manual
Page 12: Be1-50/51b-244 pickup, Dropout, Characteristic curves, Fixed timing, Reset, Instantaneous overcurrent a (50-a) element, Advantages -2
1-2
BE1-50/51B-244 General Information
9252000793 Rev C
Westinghouse CO type curves, and instantaneous or integrating reset characteristics. Switch location and
description is provided in Section 2.
Advantages
BE1-50/51B-244 overcurrent relays have many advantages over other overcurrent relays. The primary
advantages are:
•
Time characteristics are defined by equations and graphs
•
Field selectable time characteristics
•
Very low burden extends the linear range of the CTs
•
Self powered from the sensed current
•
Continuous automatic calibration
BE1-50/51B-244 overcurrent relays may be tested without removing the relay from the case. Shorting
contacts are provided for all current inputs when the connection plug is removed from the relay case.
Specifications
BE1-50/51B-244 electrical and physical specifications are listed in the following paragraphs.
Time Overcurrent (51) Element
Setting Range:
0.5 to 15.9 Aac
BE1-50/51B-244 Pickup
Setting Increment:
0.1 Aac
Accuracy:
Sum of ±2% and ±25 mAac
Dropout occurs at 95% of pickup value.
Dropout
Available curve types follow IEEE Standard C37.112 (1996) and emulate standard GE IAC,
Westinghouse CO, and BS142 curves. Appendix A, Characteristic Curves illustrates the available curves
and lists the applicable constants.
Characteristic Curves
Curve Types:
Short Inverse, Long Inverse, Definite Time, Moderately Inverse, Inverse,
Very Inverse, Extremely Inverse, BS142 Very Inverse, BS142 Extremely
Inverse, Fixed Time
Time Multiplier:
11 curves for each characteristic
Timing Accuracy:
±
1 cycle, ±2%. This accuracy applies to the range of 1.3 to 40 times tap
and is for a given measured multiple of tap.
Setting Range:
0.1 to 9.9 s
Fixed Timing
Setting Increment:
0.1 s
Timing Accuracy:
±
1 cycle, ±2% of the time to trip for time dial settings ≥ 0.1.
Integrating:
Simulates the disk reset of electromechanical relays and begins when
the current decreases below 95% of pickup. Appendix A, Characteristic
Curves illustrates the integrating reset characteristic curve and equation.
Reset
Instantaneous:
Reset occurs within 16 ms of when the current decreases below 95% of
the pickup level.
Instantaneous Overcurrent A (50-A) Element
Setting Range:
2 to 99 Aac
BE1-50/51B-244 Pickup
Setting increment:
1 Aac
Accuracy:
Sum of ±2% and ±25 mAac
Dropout occurs at 95% of pickup value.
Dropout