When phase-to-ground 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
M15326-6 v6
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.
9.1.7.2 Time delay
M15326-10 v12
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
The type A curve is described as:
ANSIEQUATION1431 V1 EN-US (Equation 170)
where:
Vpickup< Set value for step 1 and step 2
V Measured voltage
The type B curve is described as:
2.0
480
0.055
Vpickup < -V
32 0.5
Vpickup
TD
t
×
= +
× -
<
æ ö
ç ÷
è ø
EQUATION1608 V1 EN-US (Equation 171)
The customer programmable curve can be created as:
Section 9 1MRK 502 066-UUS B
Voltage protection
604
Technical manual
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