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-
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
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