Standard Inverse-Time Characteristics For Undervoltage Protection - ABB RELION Series Technical Manual

1MRS758755 A
11.3.2.1
REC615 and RER615
Technical Manual
time mode. The set value depends on the selected curve type and the setting values
used. The user determines the curve scaling with the Time multiplier setting.
The Minimum operate time setting defines the minimum operate time possible for the
IDMT mode. For setting a value for this parameter, the user should carefully study the
particular IDMT curve.

Standard inverse-time characteristics for undervoltage protection

The operate times for the standard undervoltage IDMT curves are defined with the
coefficients A, B, C, D and E.
The inverse operate time can be calculated with the formula:
k A
⋅
t s
 
=
   
U U
< −

B C
× −

U
<

GUID-4A433D56-D7FB-412E-B1AB-7FD43051EE79 V2 EN
t [s] operate time in seconds
U measured voltage
U< the set value of the
k the set value of the
Table 711: Curve coefficients for standard undervoltage IDMT curves
Curve name A
(21) Inverse 1
Curve A
(22) Inverse 480
Curve B
General function block features
D
+
E



Start value setting
Time multiplier setting
B C
1 0
32 0.5
Section 11
(Equation 85)
D E
0 1
0.055 2
753