Time Delay - ABB REC650 Technical Manual

1MRK 511 287-UEN A
7.2.7.2
Technical manual

Time delay

The time delay for step 1 can be either definite time delay (DT) or inverse time delay
(IDMT). Step 2 is always definite time delay (DT). For the inverse time delay three
different modes are available:
• inverse curve A
• inverse curve B
• inverse curve C
The type A curve is described as:
k
=
t
- >
æ ö
U U
ç ÷
>
è U ø
IEC09000051 V1 EN
The type B curve is described as:
×
k 480
=
t
æ - > ö
U U
ç × - ÷
32 0.5
è ø
>
U
IECEQUATION2287 V1 EN
The type C curve is described as:
×
k 480
=
t
æ - > ö
U U
ç × - ÷
32 0.5
è ø
>
U
IECEQUATION2288 V1 EN
The highest phase (or phase-to-phase) voltage is always used for the inverse time
delay integration, see Figure
characteristics are shown in section
-
0.035
2.0
+
0.035
3.0
72. The details of the different inverse time
"Inverse time
Section 7
Voltage protection
characteristics".
(Equation 37)
(Equation 38)
(Equation 39)
167