ABB Relion 670 series, Technical Manual

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Vpickup VBase kV
> ⋅
(%) ( ) / 3
EQUATION1610 V2 EN-US
(Equation 174)
and operation for phase-to-phase voltage over:
Vpickup (%) VBase(kV)
> ×
EQUATION1992 V1 EN-US
(Equation 175)
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
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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 176)
where:
Vpickup> Set value for step 1 and step 2
V Measured voltage
The type B curve is described as:
1MRK 502 066-UUS B Section 9
Voltage protection
617
Technical manual