The phase reference does not work if the current channel is not available.
For example, when the circuit breaker is opened and no current flows.
Although the phase angle difference between the different phases is firm,
the whole system appears to be rotating when the measurement functions
are observed.
4.2.2
Relationships between setting parameter Base Current, CT
rated primary current and minimum pickup of a protection IED
Note that for all line protection applications the parameter Base Current (i.e. IBase setting
in the IED) used by the relevant protection function, shall always be set equal to the largest
rated CT primary current among all CTs involved in the protection scheme. The rated CT
primary current value is set as parameter
CTPrim
under the IED TRM settings.
For all other protection applications (e.g. transformer protection) it is typically desirable
to set
IBase
parameter equal to the rated current of the protected object. However this is
only recommended to do if the rated current of the protected object is within the range of
40% to 120% of the selected CT rated primary current. If for any reason (e.g. high
maximum short circuit current) the rated current of the protected object is less than 40%
of the rated CT primary current, it is strongly recommended to set the parameter
IBase
in
the IED to be equal to the largest rated CT primary current among all CTs involved in the
protection scheme and installed on the same voltage level. This will effectively make the
protection scheme less sensitive; however, such measures are necessary in order to avoid
possible problems with loss of the measurement accuracy in the IED.
Regardless of the applied relationship between the
IBase
parameter and the rated CT
primary current, the corresponding minimum pickup of the function on the CT secondary
side must always be verified. It is strongly recommended that the minimum pickup of any
instantaneous protection function (e.g. differential, restricted earth fault, distance,
instantaneous overcurrent, etc.) shall under no circumstances be less than 4% of the used
IED CT input rating. This corresponds to 40mA secondary for main CTs with 1A rating
and to 200mA secondary for main CTs with 5A rating. This shall be individually verified
for all current inputs involved in the protection scheme.
4.2.3
Setting of current channels
The direction of a current depends on the connection of the CT. Unless indicated
otherwise, the main CTs are supposed to be Wye (star) connected. The IED can be
connected with its grounding point towards the object or away from the object. This
information must be set in the IED via the parameter
CT_WyePoint
, which can be changed
between
FromObject
and
ToObject
. Internally in the IED algorithms and IED functions,
the convention of the directionality is defined as follows:
Section 4
1MRK 511 286-UUS A
Analog inputs
62
Application manual
Содержание REC650 ANSI
Страница 1: ...Relion 650 series Bay control REC650 ANSI Application manual...
Страница 2: ......
Страница 26: ...20...
Страница 66: ...Section 3 1MRK 511 286 UUS A REC650 setting examples 60 Application manual...
Страница 71: ...IED IED ANSI05000460 V2 EN 1MRK 511 286 UUS A Section 4 Analog inputs 65 Application manual...
Страница 82: ...76...
Страница 92: ...86...
Страница 170: ...164...
Страница 176: ...170...
Страница 274: ...268...
Страница 288: ...282...
Страница 350: ...344...
Страница 369: ...363...