Measurement Principle - ABB REB650 Technical Manual

1MRK 505 277-UUS C
8.2.7.1
8.2.7.2
Technical Manual
Vpickup (%) VBase kV (
> ⋅
EQUATION1610 V2 EN
and operation for phase-to-phase voltage over:
> ×
Vpickup (%) VBase(kV)
EQUATION1992 V1 EN
When phase-to-ground voltage measurement is selected the function
automatically introduces division of the base value by the square root
of three.

Measurement principle

All the three voltages are measured continuously, and compared with the set values,
Pickup1 and Pickup2. 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 has been included.
Time delay
The time delay for step 1 can be either definite time delay (DT) or inverse time
overvoltage (TOV). Step 2 is always definite time delay (DT). For the inverse time
delay three different modes are available:
• inverse curve A
• inverse curve B
• inverse curve C
The type A curve is described as:
TD
t
=
V Vpickup
− >
Vpickup
>
EQUATION1625 V2 EN
The type B curve is described as:
) / 3
Section 8
Voltage protection
(Equation 29)
(Equation 30)
(Equation 31)
133