Time Curve Characteristics; Inverse Overcurrent (51) - Basler BE1-11g Instruction Manual

9424200994 Rev U

Time Curve Characteristics

This chapter provides time curve information for the inverse overcurrent (51), under/overvoltage (27/59),
and overexcitation (24) functions of the BE1-11g.

Inverse Overcurrent (51)

General
The inverse overcurrent (51) time curves provided by the BE1-11g closely emulate most of the common
electromechanical, induction-disk, overcurrent relays sold in North America. To further improve proper
BE1-11g coordination, selection of integrated reset or instantaneous reset characteristics is also provided.
Curve Specifications
Timing Accuracy (All 51 Functions): Within ±5% or ±1½ cycles, whichever is greater, for time dial settings
greater than 0.1 and multiples of 2 to 40 times the pickup setting but not over 150 A for 5 A CT units or
30 A for 1 A CT units.
Twenty-two inverse time functions, one fixed time function, one 46 time function, one programmable time
function, and four Table Curve functions can be selected. Characteristic curves for the inverse and
definite time functions are defined by the following equations and comply with IEEE Std C37.112 - 1996 -
IEEE Standard Inverse-Time Characteristic Equations for Overcurrent Relays.
= Time to trip when M ≥ 1
T
T
= Time to reset if BE1-11g is set for integrating reset when M < 1. Otherwise, reset is
T
R
50 milliseconds or less
D = Time Dial setting (0.0 to 9.9)*
M = Multiple of Pickup setting (0 to 40)
A, B, C, N, K = Constants for the particular curve
R = Constant defining the reset time.
* Timing range is one second times the Time Dial setting when the F (fixed) curve is selected.
Table 256 lists time characteristic curve constants. See the figures after the tables for graphs of the
characteristics.
Curve
Curve Name
Selection
S1
CO Short Inverse
S2 IAC Short Inverse
A Standard Inverse
A1 IEC Inverse
I1 CO Inverse Time
BE1-11g
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Equation 35
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Equation 36
Table 256. 51 Time Characteristic Curve Constants
A
0.2663
0.0286
0.01414
0.14
8.9341
+ �������� + ����
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− 1|
2
Trip Characteristic Constants
B C
0.03393 1 1.2969
0.0208 1 0.9844
0 1
0 1
0.17966 1 2.0938
Reset ∗
N K R
0.028 0.5
0.028 0.094
0.02 0.028 2
0.02 0 2
0.028 9
Time Curve Characteristics
603