ABB Relion 670 series - Measurement principle; Time delay

function is blocked and no PICKUP or TRIP signal is generated.The time delay
characteristic is individually chosen for each step and can be either definite time delay
or inverse time delay.
UV2PTUV (27) can be set to measure phase-to-ground fundamental value, phase-to-
phase fundamental value, phase-to-ground true RMS value or phase-to-phase true
RMS value. The choice of the measuring is done by the parameter ConnType. The
voltage related settings are made in percent of base voltage which is set in kV phase-to-
phase voltage. This means operation for phase-to-ground voltage under:
(%) ( )
3
Vpickup VBase kV< ×
EQUATION1606 V1 EN (Equation 117)
and operation for phase-to-phase voltage under:
Vpickup (%) VBase(kV)< ×
EQUATION1991-ANSI V1 EN (Equation 118)
When phase-to-ground voltage measurement is selected the function
automatically introduces division of the base value by the square root
of three.
8.1.2.1 Measurement principle
Depending on the set ConnType value, UV2PTUV (27) measures phase-to-ground or
phase-to-phase voltages and compare against 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 lower than the corresponding set point to issue the corresponding PICKUP signal.
To avoid oscillations of the output PICKUP signal, a hysteresis has been included.
8.1.2.2 Time delay
The time delay for the two steps can be either definite time delay (DT) or inverse time
undervoltage (TUV). For the inverse time delay three different modes are available:
• inverse curve A
• inverse curve B
• customer programmable inverse curve
Section 8 1MRK505222-UUS C
Voltage protection
492
Technical reference manual