9328900990 Rev L BE1-951 Time Overcurrent Characteristic Curves A-3
Table A-2. Characteristic Curve Cross-Reference
Curve Curve Name Similar To
S1
S, S1, Short Inverse ABB CO-2
S2
S2, Short Inverse GE IAC-55
L1
L, L1, Long Inverse ABB CO-5
L2
L2, Long Inverse GE IAC-66
D
D, Definite Time ABB CO-6
M
M, Moderately Inverse ABB CO-7
I1
I, I1, Inverse Time ABB CO-8
I2
I2, Inverse Time GE IAC-51
V1
V, V1, Very Inverse ABB CO-9
V2
V2, Very Inverse GE IAC-53
E1
E, E1, Extremely Inverse ABB CO-11
E2
E2, Extremely Inverse GE IAC-77
A
A, Standard Inverse BS, IEC Standard Inverse
B
B, Very Inverse (I
2
t) BS, IEC Very Inverse (I
2
t)
C
C, Extremely Inverse (I
2
t) BS, IEC Extremely Inverse (I
2
t)
G
G, Long Time Inverse (I
2
t) BS, IEC Long Time Inverse (I
2
t)
F
Fixed Time N/A
P
Programmable N/A
Time Dial Setting Cross-Reference
Although the time characteristic curve shapes have been optimized for each relay, time dial settings of
Basler Electric relays are not identical to the settings of electromechanical induction disk overcurrent
relays.
Table A-3 helps you convert the time dial settings of induction disk relays to the equivalent setting
for Basler Electric relays. Enter time dial settings using BESTCOMS, S<g>-51P/51N/51Q/151N ASCII
commands, or human-machine interface (HMI) Screens 5.x.7.1 (51P), 5.x.7.2 (51N), 5.x.7.3 (51Q), and
5.x.7.4 (151N). For more information, refer to Section 4, Protection and Control, Overcurrent Protection,
51 – Time Overcurrent Protection.
Using
Table A-3
Cross-reference table values were obtained by inspection of published electromechanical time current
characteristic curves. The time delay for a current of five times tap was entered into the time dial
calculator function for each time dial setting. The equivalent Basler Electric time dial setting was then
entered into the cross-reference table.
If your electromechanical relay time dial setting is between the values provided in the table, it will be
necessary to interpolate (estimate the correct intermediate value) between the electromechanical setting
and the Basler Electric setting.
Basler Electric relays have a maximum time dial setting of 9.9. The Basler Electric equivalent time dial
setting for the electromechanical maximum setting is provided in the cross-reference table even if it
exceeds 9.9. This allows interpolation as noted above.
Basler Electric time current characteristics are determined by a linear mathematical equation. The
induction disk of an electromechanical relay has a certain degree of non linearity due to inertial and
friction effects. For this reason, even though every effort has been made to provide characteristic curves
with minimum deviation from the published electromechanical curves, slight deviations can exist between
them.
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