Vpickup VBase kV> ⋅(%) ( ) / 3
EQUATION1610 V2 EN-US (Equation 174)
and operation for phase-to-phase voltage over:
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
M15330-10 v9
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:
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
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