GRD130
3
PROTECTION FUNCTIONS
Phase Overvoltage Protection
GRD130 overvoltage protection provides three
independent overvoltage thresholds. The first and
second thresholds may be set for inverse time or
definite time operation. The third threshold can be
programmed for definite time operation.
The first and second thresholds has a programmable
reset feature, selectable for instantaneous or definite
time operation. Each element gives outputs for alarm
and trip, and each trip output can be inhibited by
binary input.
Phase Undervoltage Protection
GRD130 undervoltage protection provides three
independent undervoltage thresholds. The first and
second thresholds may be set for inverse time or
definite time operation. The third threshold can be
programmed for definite time operation.
The first and second thresholds has a programmable
reset feature, selectable for instantaneous or definite
time operation. Each element gives outputs for alarm
and trip, and each trip output can be inhibited by
binary input.
An undervoltage blocking function prevents undervoltage
tripping in the case of a dead line.
Zero Phase Sequence Overvoltage
Protection (ZPS)
GRD130 provides ZPS protection with two independent
overvoltage thresholds. The two thresholds may be
set for inverse time or definite time operation. The two
thresholds have a programmable reset feature,
selectable for instantaneous or definite time operation.
In the case of GRD130-410, the zero sequence voltage,
V
0
may either be calculated from the three measured
phase voltages, or it may be measured directly in the
form of the system residual voltage, typically using a
five limb VT.
In the case of GRD130-210, the V
0
must be measured
directly.
The low voltage settings which may be applied make
the ZPS element susceptible to any 3
rd
harmonic
component which may be superimposed on the input
signal. Therefore, a 3
rd
harmonic filter is provided to
suppress such superimposed components.
Each element gives outputs for alarm and trip, and
each trip output can be inhibited by binary input.
Negative Phase Sequence Overvoltage
Protection (NPS)
GRD130 provides NPS protection with two independent
overvoltage thresholds. The two thresholds may be
set for inverse time or definite time operation.
The two thresholds have a programmable reset
feature, selectable for instantaneous or definite time
operation. Each element gives outputs for alarm and
trip, and each trip output can be inhibited by binary
input.
Figure 1 - IDMT curves for Overvoltage, Undervoltage and ZPS, NPS Overvoltage
Inverse Time Operate Curves
Ov erv oltage Inv erse Time Curv es
0.100
1.000
10.000
100.000
1000.000
1
1.5
2
2.5
3
Applied Voltage (x Vs)
O
p
er
ating Time (secs)
TMS = 1
TMS = 2
TMS = 5
TMS = 10
Undervoltage Inverse Time Curves
1.000
10.000
100.000
1000.000
0
0.2
0.4
0.6
0.8
1
Applied Voltage (x Vs)
O
p
erat
ing Ti
me (
secs)
TMS = 10
TMS = 5
TMS = 2
TMS = 1
ZPS, NPS Overvoltage Inverse Time Curves
0.010
0.100
1.000
10.000
100.000
1000.000
0
5
10
15
20
Applied Voltage (x Vs)
O
p
erati
ng Ti
me (secs)
TMS = 10
TMS = 5
TMS = 2
TMS = 1
( )
xTMS
Vs
V
t
1
1
−
=
( )
xTMS
Vs
V
t
−
=
1
1
( )
xTMS
Vs
V
t
1
1
−
=
Summary of Contents for GRD130
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