54
NV021 - Manual - 08 - 2012
CHARACTERISTICS
Negative sequence overvoltage - 59V2
[1]
Preface
The protection has an adjustable threshold and defi nite time characteristic.
Enabling or disabling is provided by means ThySetter.
Operation and settings
The negative sequence voltage is calculated as:
U
2
=(
U
12
+e
-j120°
·
U
23
+e
+j120°
·
U
31
)/3 where
U
12
,
U
23
e
U
31
are the direct measurement of line-to-line volt-
ages and with e
-j120°
=-1/2-j√3/2, e
j120°
=-1/2+j√3/2.
The negative sequence voltage is compared with the threshold (
U
2>def
).
A start is issued when the negative sequence voltage overcomes the adjustable threshold threshold
(START).
After expiry of the associated operate time (
t
U2
>) a trip command is issued; if instead the voltages
drops below the threshold, the element it is restored.
The element can be enabled or disabled by setting
ON
or
OFF
the
State
parameter inside the
Set \
Profi le A(or B) \ Negative sequence overvoltage-59V2 \ U2> Element \ Defi nite time
menu
Breaker failure (BF)
The negative sequence overvoltage element can produce the Breaker Failure output if the
U2>BF
parameter is set to
ON.
The parameter ia available inside the
Set \ Profi le A(or B) \ Negative sequence overvoltage - 59V2 \
U2> Element \ Setpoints
menu.
[2]
All the parameters can be set separately for
Profi le A
and
Profi le B
.
Logical block (Block1)
If the
U2>BLK1
enabling parameter is set to
ON
and a binary input is designed for logical block
(Block1), the protection is blocked off whenever the given input is active.
The trip timer is held in reset condition, so the operate time counting starts when the input block goes
down.
[3]
The enabling parameter is available inside the
Set \ Profi le A(or B) \ Negative sequence
overvoltage - 59V2 \
U2> Element \ Setpoints
menu, while the
Block1
function must be assigned to
the selected binary input inside the
Set \ Inputs \ Binary input IN1(x)
menus (IN1 or INx matching).
Nota 1 La funzione è signifi cativa solo in applicazioni su rete trifase
Note 2 The common settings concerning the Breaker failure protection are adjustable inside the
Breaker Failure - BF
menu.
Note 3 The exhaustive treatment of the logical block (Block 1) function may be found in the “Logic Block” paragraph inside
CONTROL AND MONITOR-
ING
section.
—
U
2
U
2
>
def
t
t
U 2
>
def
General operation time characteristic for the negative sequence overvoltage element - 59V2
TRIP
U
2
U
2
>
def
t
t
U 2
>
def
General operation time characteristic for the negative sequence overvoltage element - 59V2
TRIP
all-597V2.ai
General characteristic for the negative sequence overvoltage element - 59V2
U2> Element
Start U2>
Trip U2>
t
U2> def
U
2
>
def
State
Block1
BLK1U2>
&
U2>BLK1
Start U2>
&
U2>BF
Trip U2>
&
U2>BF
U
2
all-597V2.ai
General characteristic for the negative sequence overvoltage element - 59V2
U2> Element
Start U2>
Trip U2>
t
U2> def
U
2
>
def
State
Block1
BLK1U2>
&
U2>BLK1
Start U2>
&
U2>BF
Trip U2>
&
U2>BF
U
2