ABB Relion 670 Series Technical Reference Manual page 499

1MRK505222-UUS C
Technical reference manual
The type A curve is described as:
TD
=
t
< -
Vpickup V
<
Vpickup
ANSIEQUATION1431 V1 EN
where:
Vpickup Set value for step 1 and step 2
<
V Measured voltage
The type B curve is described as:
×
TD 480
=
t
æ
Vpickup < -V
× -
ç
32 0.5
è
<
Vpickup
EQUATION1608 V1 EN
The customer programmable curve can be created as:
é
ê
×
TD A
ê
=
t
ê
æ
< -
Vpickup V
ê × -
B C
ç
è
ë Vpickup
EQUATION1609 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:
CrvSatn
× - >
B C 0
100
EQUATION1435 V1 EN
+
0.055
2.0
ö
÷
ø
ù
ú
ú
+
D
ú
P
ö
ú
÷
ø
û
Section 8
Voltage protection
(Equation 119)
(Equation 120)
(Equation 121)
(Equation 122)
493