The setting of the analog inputs are given as primary phase-to-earth or phase-to-phase
voltage. OV2PTOV will operate if the voltage gets higher than the set percentage of
the set base voltage
UBase
. This means operation for phase-to-earth voltage over:
(%)
(
)
3
U
UBase kV
>
×
EQUATION1434 V1 EN
(Equation 110)
and operation for phase-to-phase voltage over:
U
(%) UBase(kV)
>
×
EQUATION1993 V1 EN
(Equation 111)
When phase-to-earth 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
All the three voltages are measured continuously, and compared with the set values,
U1>
for Step 1 and
U2>
for Step 2. 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 higher than the corresponding set point to
issue the corresponding START signal.
To avoid oscillations of the output START signal, a hysteresis is included.
9.2.7.2
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 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:
n
n
k
t
U U
U
=
æ
ö
-
>
ç
÷
>
è
ø
IECEQUATION2422 V1 EN
(Equation 112)
Section 9
1MRK502052-UEN B
Voltage protection
496
Technical manual
Содержание Relion REG670
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