ABB Relion 670 series, Technical Reference Manual

Page: 513 / 1232

8.2.2.2 Time delay
The time delay for the two steps can be either definite time delay (DT) or inverse time
delay (TOV). For the inverse time delay four different modes are available:
• inverse curve A
• inverse curve B
• inverse curve C
• customer programmable inverse curve
The type A curve is described as:
t
TD
V Vpickup
Vpickup
=
− >
>
EQUATION1625 V2 EN
(Equation 125)
The type B curve is described as:
t
TD
V Vpickup
Vpickup
=
⋅
⋅
− >
>
−
−
480
32 0 5
0 035
.
.
ANSIEQUATION2287 V2 EN
(Equation 126)
The type C curve is described as:
t
TD
V Vpickup
Vpickup
=
⋅
⋅
− >
>
−
+
480
32 0 5
0 035
.
.
ANSIEQUATION2288 V2 EN
(Equation 127)
The customer programmable curve can be created as:
P
TD A
t D
V Vpickup
B C
Vpickup
×
= +
-
× -
æ ö
ç ÷
è ø
EQUATION1616 V1 EN
(Equation 128)
When the denominator in the expression is equal to zero the time delay will be infinity.
There will be an undesired discontinuity. Therefore, a tuning parameter
CrvSatn is set
to compensate for this phenomenon. In the voltage interval Vpickup down to Vpickup
· (1.0 –
CrvSatn /100) the used voltage will be: Vpickup · (1.0 – CrvSatn /100). If the
programmable curve is used this parameter must be calculated so that:
1MRK505222-UUS C
Section 8
Voltage protection
507
Technical reference manual