Basler Electric DGC-2020HD - Manual (Page 349)

9469300990 Rev B 339
Time Curve Characteristics
The inverse time overcurrent characteristic curves provided by the DGC-2020HD (style xxExxxxxx only)
closely emulate most of the common electromechanical, induction-disk, overcurrent relays sold in North
America. To further improve proper relay coordination, a selection of integrated reset or instantaneous
reset characteristics are also provided.
Curve Specifications
Timing Accuracy ............................... Within ±500 milliseconds of indicated operating point.
Sixteen inverse time functions, one fixed time function, one 46 time function, and one programmable time
function 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 - IEEE Standard Inverse-Time Characteristic
Equations for Overcurrent Relays.
𝑇
𝑇
=
𝐴𝐷
(𝑀 𝑁 − 𝐶) 𝑄
+ 𝐵𝐷 + 𝐾
Equation 10
𝑇
𝑅
=
𝑅𝐷
|𝑀 2 − 1|
Equation 11
T
T
= Time to trip when M
≥ 1
T
R
= Time to reset if relay 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
Q = Denominator exponent
∗ Timing range is 0.0 to 7,200 seconds when the F (fixed) curve is selected.
Table 94 lists time characteristic curve constants. See the figures after the tables for graphs of the
characteristics.
DGC-2020HD Time Curve Characteristics