ABB Relion 670 series - Page 499

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