CHARACTERISTICS
53
NV10B - Manual - 04 - 2022
Residual overvoltage - 59N
Preface
Two operation thresholds, independently adjustable (
U
E
>,
U
E
>>) with adjustable delay (
t
UE
>,
t
UE
>>).
The fundamental component of the residual voltage is computed, therefore the element is insensitive
to the third harmonic components.
The first threshold (
U
E
>) can be programmed with definite or inverse time, while the second thresh-
old operates with definite time characteristic.
Each threshold may be separately enabled or disabled.
The first threshold trip (
U
E
>) may be inhibited by start of the second threshold (
U
E
>>).
Operation and settings
Two measuring criteria of the residual voltage are provided:
• Direct
• Calculated.
For direct measure the fundamental component of the residual voltage input is used (
U
E
), whereas,
for calculated measure (
U
EC
) the residual voltage comes from a vector sum of three phase voltage
phasors.
The residual voltage (
U
E
or
U
EC
) is compared with the setting values (
U
E
>,
U
E
>>); a start is issued
when the residual voltage overcomes the adjustable threshold (START); after expiry of the associ-
ated operate time (
t
UE
>,
t
UE
>>) a trip command is issued; if instead the voltage drops below the
threshold, the element is restored.
The first threshold (
U
E
>) may be programmed with definite or inverse time according the following
characteristic curve:
t
=0.5
t
UE
>
inv
/ [(
U
E
/
U
E
>
inv
) - 1] or
t
=0.5
t
UE
>
inv
/ [(
U
EC
/
U
E
>
inv
) - 1]
Where:
U
E
:
measured residual voltage
U
EC
:
calculated residual voltage
t
:
operate time
U
E
>
inv
:
pickup value
t
UE>inv
:
operate time setting
For the inverse time characteristic, following data applies:
• The operate time setting is referred to an input voltage equal to 1.5 of the pickup value.
• Asymptotic reference value (minimum pickup value): 1.1
U
E
>
inv
• Minimum operate time: 0.1
s
• Range where the equation is valid: 1.1 ≤
U
E
/
U
E
>
inv
(
U
EC
/
U
E
>
inv
) ≤ 4
• If
U
E
>
inv
pickup ≥ 0.5
U
En
, the upper limit is 2
U
En
.
The first residual overvoltage element can be programmed with definite or inverse time character-
istic by setting the
UE> Curve
parameter (
DEFINITE, INVERSE
) available inside the
Set \ Profile
A(or B) \ Residual overvoltage-59N \
UE
> Element \ Setpoints
menu.
For definite time characteristic the upper limit is 2
U
En
.
Each element can be enabled or disabled by setting
ON
or
OFF
the
UE> Enable
parameter inside
the
Set \ Profile A(or B) \ Residual overvoltage-59N \
UE
> Element \ Setpoints
menu and/or the
State
parameter inside the
Set\Profile A(or B) \ Residual overvoltage-59N \
UE
>> Element \ Definite time
.
Selection of the measuring criteria of the residual voltage (direct measure or calculated measure) is
available inside the
Set \ Profile A(or B) \ Residual overvoltage-59N \
Common
configuration
menu;
The
3Votype59N
parameter may be select as
UE
(direct measure) or
UEC
(calculated measure).
With
UE
setting (direct voltage measurement), the thresholds are in p.u.
U
En
, with
UEC
setting (cal-
U
EC
=|
U
L1
+
U
L2
+
U
L3
|
t-int-F59N.ai
U
E
U
E
>>
t
UE
>
t
UE
>>
U
E
>
t
General operation time characteristic for the residual overvoltage elements - 59N
TRIP
