Basler Electric BE1-11m - Manual (Page 471)

9424200996 Rev L 459
Time Curve Characteristics
This chapter provides time curve information for the inverse overcurrent (51), under/overvoltage (27/59),
and thermal curve (49TC) functions of the BE1-11m.
Inverse Overcurrent (51)
General
The inverse overcurrent (51) time curves provided by the BE1-11m closely emulate most of the common
electromechanical, induction-disk, overcurrent protection systems sold in North America. To further
improve proper BE1-11m 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.
𝑇
𝑇
=
𝐴𝐷
𝑀 𝑁 − 𝐶 + 𝐵𝐷 + 𝐾
Equation 26
𝑇
𝑅
=
𝑅𝐷
|𝑀 2 − 1|
Equation 27
T
T
= Time to trip when M
≥ 1
T
R
= Time to reset if BE1-11m is set for integrating reset when M
< 1. Otherwise, reset is 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 192 lists time characteristic curve constants. See the figures after the tables for graphs of the
characteristics.
Table 192. 51 Time Characteristic Curve Constants
Curve
Selection
Curve Name
Trip Characteristic Constants Reset
∗
A B C N K R
S1 CO Short Inverse 0.2663 0.03393 1 1.2969 0.028 0.5
S2 IAC Short Inverse 0.0286 0.0208 1 0.9844 0.028 0.094
A Standard Inverse 0.01414 0 1 0.02 0.028 2
BE1-11m Time Curve Characteristics