ABB REF615 L User Manual

inverse-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.
11.3.2.1 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:
t s
k A
B
U U
U
C
D
E






=
⋅
×
< −
<
−






+
GUID-4A433D56-D7FB-412E-B1AB-7FD43051EE79 V2 EN (Equation 107)
t [s] operate time in seconds
U measured voltage
U< the set value of the Start value setting
k the set value of the Time multiplier setting
Table 662: Curve coefficients for standard undervoltage IDMT curves
Curve name
A B C D E
(21) Inverse
Curve A
1 1 0 0 1
(22) Inverse
Curve B
480 32 0.5 0.055 2
1YHT530004D05 D Section 11
General function block features
615 series 835
Technical Manual

ABB REF615 L Specifications

General

Type	Feeder Protection Relay
Rated Frequency	50/60 Hz
Weight	Approx. 1.5 kg
Communication Protocols	IEC 61850, Modbus RTU, DNP3
Protection Functions	Overcurrent, Earth fault, Thermal overload, Under/Over voltage, Under/Over frequency
Enclosure	IP20