1-2
BE1-50/51B-235/-236 General Information
9252000898 Rev —
curves, and instantaneous or integrating reset characteristics. Switch location and description is provided
in Section 2.
Advantages
BE1-50/51B-235 and BE1-50/51B-236 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-235 and BE1-50/51B-236 overcurrent relays may be tested without removing the relay from
the case. Shorting contacts are provided for all current inputs when the connection plugs or relay chassis
is removed from the relay case.
SPECIFICATIONS
BE1-50/51B-235 and BE1-50/51B-236 electrical and physical specifications are listed in the following
paragraphs.
Time Overcurrent (51) Element
BE1-50/51B-235 Pickup
Setting Range:
0.5 to 15.9 Aac
Setting Increment:
0.1 Aac
Accuracy: Sum
of
±
2% and
±
25 mAac
BE1-50/51B-236 Pickup
Setting Range:
0.1 to 3.18 Aac
Setting Increment:
0.02 Aac
Accuracy: Sum
of
±
2% and
±
5 mAac
Dropout
Dropout occurs at 95% of pickup value.
Characteristic Curves
Available curve types follow IEEE Standard C37.112 (1996) and emulate standard GE IAC, ABB CO, and
BS142 curves. Appendix A,
Characteristic Curves
illustrates the available curves and lists the applicable
constants.
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.
Fixed Timing
Setting Range:
0.1 to 9.9 s
Setting Increment:
0.1 s
Timing Accuracy:
±
1 cycle,
±
2% of the time to trip for time dial settings
≥
0.1.
Reset
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.
Instantaneous:
Reset occurs within 16 ms of when the current decreases below 95% of
the pickup level.
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