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BE1-50/51B-233 General Information
9252000897 Rev A
Advantages
BE1-50/51B-233 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-233 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-233 electrical and physical specifications are listed in the following paragraphs.
Current Sensing Input
Continuous Current:
14 Aac
One Second Rating:
400 Aac
Time Overcurrent (51) Element
Setting the TIME PICKUP control at the minimum pickup setting places the relay in the most sensitive
state and may be used as a safety setting.
Pickup
Setting Range:
0.5 to 15.9 Aac
Setting Increment:
0.1 Aac
Accuracy:
±2%, ±25 milliamperes at or above 0.5 ampere setting
Dropout
Dropout occurs at 95% of pickup value.
Timing Range
0.0 to 9.9 seconds in 0.1 second steps
Timing Accuracy
The timing accuracy is the sum of ±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. The measurement of the multiple of tap has an accuracy that
is the sum of ±2%, ±25 milliamperes.
Timing Accuracy Example
PU
setting:
5
amperes
Current Applied:
6.5 amperes
+ Multiple Tolerance:
6.655 amperes
– Multiple Tolerance:
6.345 amperes
Time
Curve:
E
Time
Dial:
5.0
Minimum time dial
using 6.655 amperes:
46.5470 seconds
Maximum time dial
using 6.345 amperes:
61.3968 seconds
Curve time using 6.5 amperes: 53.1800 seconds
Curve Characteristics
Nine inverse time functions and one fixed time function can be selected by the front-panel Curve switch.
Characteristic curves for the inverse and definite time functions are defined by the following equation.
Where: T
T
=
time to trip in seconds
D =
time dial setting
M =
multiple of pickup setting
A, B, C, N, K =
constants for the particular curve
K
BD
C
M
AD
T
N
T
+
+
=
-
Summary of Contents for BE1-50/51B-233
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