Thytronic NC20 User Manual

106
106
NC2 0 - Manual - 01 - 2015
FUNCTION CHARACTERISTICS
Overvoltage - 59
Preface
Two operation thresholds, independently adjustable (U>, U>>) with adjustable delay (t
U
>, t
U
>>).
The fi rst one may be programmed with defi nite or inverse time, while the second threshold operates
with defi nite time characteristic.
Each threshold may be separately enabled or disabled.
The fi rst threshold trip (U>) may be inhibited by start of the second threshold (U>>).
Operation and settings
The fundamental frequency of the input voltages (U
L1
, U
L2
, U
L3
) are utilized.
Each of three voltages is compared with the setting values (U>, U>>). The start and trip logic may
be selected OR or AND.
With OR selection, a start is issued when at least one of the three voltages overcomes the adjust-
able threshold (START); after expiry of the associated operate time (t
U
>, t
U
>>) a trip command is
issued; if instead the voltages drop below the threshold, the element is restored.
With AND selection, a start is issued when all the three voltages overcomes the adjustable thresh-
old; after expiry of the associated operate time (t
U
>, t
U
>>) a trip command is issued; if instead the
voltage drops below the threshold, the element is restored.
The fi rst threshold (U>) may be programmed with defi nite or inverse time according the following
characteristic curve:
t=0.5 t
U
>
inv
/ [(U/U>
inv
) - 1]
Where:
t: operate time
U: relay input voltage
U>
inv
: threshold setting
t
U>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>
inv
Minimum operate time: 0.1 s
Range where the equation is valid: 1.1 ≤ U/U>
inv
≤ 4
If U>
inv
pickup ≥ 0.5 U
n
, the upper limit is 2 U
n
.
The fi rst overvoltage element can be programmed with defi nite or inverse time characteristic by
setting the U>Curve parameter (DEFINITE, INVERSE) available inside the Set \ Profi le A(or B) \
Overvoltage-59 \ U> Element \ Setpoints menu.
Each element can be enabled or disabled by setting ON or OFF the U> Enable parameter inside
the Set \ Profi le A(or B) \ Overvoltage-59 \ U> Element \ Setpoints menu and/or the State parameter
inside the Set \ Profi le A(or B) \ Overvoltage-59 \ U>> Element \ Defi nite time.
The operating logic (AND or OR) is adjustable inside the Set \ Profi le A(or B) \ Overvoltage-59 \ Com-
mon confi guration menu by means the Logic59 parameter; the allowed settings are OR (at least
one voltage greater than threshold) or And (all three voltage must be greater than threshold).
The fi rst threshold trip (U>) may be inhibited by start of the second threshold (U>>) by setting ON
the U> Disabling by U>> start (U>disbyU>>) parameter available inside the Set \ Profi le A(or B) \
Overvoltage-59 \ U>> Element \ Setpoints menu.
Both overvoltage elements can produce the Breaker Failure output if the U> BF and U>>BF pa-
rameters are set to ON.
The parameters are available inside the Set \ Profi le A(or B) \ Overvoltage - 59 \ U> Element (U>>
Element) \ Setpoints menus.
[1]
Note 1 The common settings concerning the Breaker failure protection are adjustable inside the Breaker Failure - BF menu.
•
•
•
•
•
t-int-F59.ai
U
U>>
t
U
>
t
U
>>
U>
t
TRIP
General operation time characteristic for the overvoltage elements - 59

Thytronic NC20 Specifications

General

Brand	Thytronic
Model	NC20
Category	Power distribution unit
Language	English