ABB Relion 670 Series Technical Reference Manual page 513

1MRK505222-UUS C
8.2.2.2
Technical reference manual
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:
TD
t
=
V Vpickup
− >
Vpickup
>
EQUATION1625 V2 EN
The type B curve is described as:
TD 480
⋅
t
= −
V Vpickup
− >
32 0 5 .
⋅ −
Vpickup
>
ANSIEQUATION2287 V2 EN
The type C curve is described as:
TD 480
⋅
t
= +
V Vpickup
− >
32 0 5 .
⋅ −
Vpickup
>
ANSIEQUATION2288 V2 EN
The customer programmable curve can be created as:
×
TD A
=
t
æ ö
-
V Vpickup
× -
ç ÷
B C
è ø
Vpickup
EQUATION1616 V1 EN
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:
0 035 .
0 035 .
+
D
P
Section 8
Voltage protection
(Equation 125)
(Equation 126)
(Equation 127)
(Equation 128)
507