Thytronic NA20, Manual, Page: 70 / 208

FUNCTION CHARACTERISTICS
70 NA20 - Manual - 04 - 2022
The second overcurrent element can be programmed with definite or inverse time characteristic by
setting the I> Time characteristic ( I>>Curve ) parameter ( DEFINITE, I2t ) available inside the
Set
\ Profile A(or B) \ Phase overcurrent-50/51 \ I>> Element \ Setpoints
menu.
The trip of I > element may be inhibited by the start of the second and/or third element ( I >>, I >>>) by set-
ting ON the Disable I> by start I>>, Disable I>> by start I>>> ( I>disbyI>>, I>disbyI>>> ) parameters
available inside the
Set \ Profile A(or B) \ Phase overcurrent-50/51 \ I>> Element
(
I>>> Element) \ Setpoints
menus.
Similarly the trip of the I >> element may be inhibited by start of the third element ( I >>>) by setting
ON the Disable I>> by start I>>> ( I>>disbyI>>> ) parameter available inside the
Set \ Profile
A(or B) \ Phase overcurrent-50/51 \ I>>> Element \ Setpoints
menu.
All the named parameters can be set separately for
Profile A
and
Profile B
(
Set \ Profile A(or B) \
Phase overcurrent-50/51 \ I> Element
(
I>> Element
,
I>>> Element) \ Setpoints
menus).
An adjustable reset time delay is provided for every threshold ( t
>RES
, t
>>RES
, t
>>>RES
).
Each overcurrent element can produce the Breaker Failure output if the I> BF , I>> BF and/or
I>>> BF parameters are set to ON. The parameters are available inside the
Set \ Profile A(or B) \
Phase overcurrent-50/51 \ I> Element
(
I>> Element
,
I>>> Element) \ Setpoints
menus.
[1]
For all overcurrent elements, a block from the second harmonic restraint may be set by setting
ON the I>2ndh-REST, I>>2ndh-REST, I>>>2ndh-REST parameters inside the
Set \ Profile
A(or B) \ Phase overcurrent-50/51 \ I> Element
(
I>> Element
,
I>>> Element) \ Setpoints
menus.
If the CLP function (Cold Load Pick-up) is enabled for element blocking, the selected threshold may
be blocked for an adjustable time interval, starting from the circuit breaker closure.
This operating mode may be select by setting ON-Element blocking the ICLP> Mode, ICLP>>
Mode and/or ICLP>>> Mode parameters.
If the CLP function (Cold Load Pick-up) is enabled for threshold change, the selected threshold may
be changed for an adjustable time interval, starting from the circuit breaker closure.
This operating mode may be select by setting ON-Change setting the ICLP> Mode, ICLP>>
Mode and/or ICLP>>> Mode parameters, whereas the operating thresholds within the CLP
may be adjusted inside the
Set \ Profile A(or B) \ Phase overcurrent-50/51 \ I> Element
,(
I>> Element
,
I>>> Element) \ Definite time (Inverse time)
menus.
For both operating modes the CLP Activation time parameters ( tCLP>, tCLP>>, tCLP>>> ) may
be adjusted inside the
Set \ Profile A(or B) \ Phase overcurrent-50/51 \ I> Element
(
I>> Element
,
I>>> Element) \ Setpoints
menus.
Note 1 The common settings concerning the Breaker failure protection are adjustable inside the Breaker Failure - BF menu.
Timers-F50-51.ai
I> Start
I> Trip
t
>
t
>
RESET
INPUT
t
>RES
t
>RES
t
>RES
t
I> element phase overcurrent timers - 50/51