ABB Relion RES670, Техническое руководство

Страница: 297 / 934

Vpickup VBase kV
> ⋅
(%) ( ) / 3
EQUATION1610 V2 EN-US
(Equation 54)
and operation for phase-to-phase voltage over:
Vpickup (%) VBase(kV)
> ×
EQUATION1992 V1 EN-US
(Equation 55)
When phase-to-ground voltage measurement is selected the function
automatically introduces division of the base value by the square root
of three.
9.2.7.1 Measurement principle
M15330-6 v6
All the three voltages are measured continuously, and compared with the set values,
Pickup1 for Step 1 and Pickup2 for Step 2. The parameters OpMode1 and OpMode2
influence the requirements to activate the PICKUP outputs. Either 1 out of 3 , 2 out of 3
or 3 out of 3 measured voltages have to be higher than the corresponding set point to
issue the corresponding PICKUP signal.
To avoid oscillations of the output PICKUP signal, a hysteresis is included.
9.2.7.2 Time delay
M15330-10 v11
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-US
(Equation 56)
1MRK 511 408-UUS A
Section 9
Voltage protection
Phasor measurement unit RES670 2.2 ANSI 291
Technical manual