Basler Electric DGC-2020HD - Manual (Page 151)

9469300990 Rev B 141
𝑇
𝑇
=
𝐴𝐷
(𝑀 𝑁 − 𝐶) 𝑄
+ 𝐵𝐷 + 𝐾
Equation 1. Time OC Characteristics for Trip
𝑇
𝑅
=
𝑅𝐷
|𝑀 2 − 1|
Equation 2. Time OC Characteristics for Reset
Table 45. Definitions for Equation 1 and Equation 2
Parameter Description Explanation
T
T
Time to trip Time that the 51-x function will take to time out and trip.
D Time dial setting Time dial setting for the 51-x function.
M Multiple of pickup
Measured current in multiples of pickup. The timing algorithm
has a dynamic range of 0 to 40 times pickup.
A
Coefficient specific to
selected curve
Affects the effective range of the time dial.
B
Coefficient specific to
selected curve Affects a constant term in the timing equation. Has greatest
effect on curve shape at high multiples of tap.
C
Coefficient specific to
selected curve
Affects the multiple of PU where the curve would approach
infinity if allowed to continue below pickup. Has greatest
effect on curve shape near pickup.
N
Exponent specific to
selected curve Affects how inverse the characteristics are. Has greatest
effect on curve shape at low to medium multiples of tap.
K Constant Characteristic minimum delay term.
T
R
Time to reset Relevant if 51-x function is set for integrating reset.
R
Coefficient specific to
selected curve
Affects the speed of reset when integrating reset is selected.
Q
Denominator exponent
specific to selected curve Affects how inverse the characteristics are. Has greater
affect as Q is increased.
Curve coefficients are entered on the Inverse Overcurrent settings screen in BESTCOMSPlus.
Programmable curve coefficients can be entered only when the P curve is chosen for the protection
element from the Curve drop-down menu.
Table Curves
BESTCOMSPlus is used to set the 51 element Table Curves (T1, T2, T3, and T4). Using the Settings
Explorer within BESTCOMSPlus, open the Protection, Current, Table Curve (1, 2, 3, or 4) tree branch and
select the table curve to be modified. Refer to Figure 77. A minimum of 2 and maximum of 40 points can
be entered for any one T curve. When you are satisfied with the values chosen, select Save Curve. Use
the Settings Explorer to browse to the 51-x element you wish to program and use the drop-down menu
under Curve to select T1, T2, T3, or T4.
Table curves can be entered regardless of the curve chosen for the protection element. However, the
table curve will not be enabled until T1, T2, T3, or T4 is selected as the curve for the protective element.
DGC-2020HD Generator Protection