ABB REG670 - Measurement Principle

UV2PTUV can be set to measure phase-to-earth fundamental value, phase-to-phase
fundamental value, phase-to-earth 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-earth voltage under:
U UBase kV< ⋅(%) ( )
3
EQUATION1429 V2 EN (Equation 104)
and operation for phase-to-phase voltage under:
U (%) UBase(kV)< ×
EQUATION1990 V1 EN (Equation 105)
When phase-to-earth voltage measurement is selected the function
automatically introduces division of the base value by the square root
of three.
9.1.7.1 Measurement principle
Depending on the set ConnType value, UV2PTUV measures phase-to-earth or phase-
to-phase voltages and compare against set values, U1< and U2<. The parameters
OpMode1 and OpMode2 influence the requirements to activate the START 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 START signal.
To avoid oscillations of the output START signal, a hysteresis has been included.
9.1.7.2 Time delay
The time delay for the two steps can be either definite time delay (DT) or inverse time
delay (IDMT). For the inverse time delay three different modes are available:
• inverse curve A
• inverse curve B
• customer programmable inverse curve
The type A curve is described as:
n
n
k
t
U U
U
=
æ ö
< -
ç ÷
<
è ø
EQUATION1431 V2 EN
(Equation 106)
Section 9 1MRK502052-UEN B
Voltage protection
482
Technical manual