
1MAC050144-MB C
Section 4
Protection functions
615 series ANSI
245
Technical Manual
The function contains a blocking functionality. It is possible to block function outputs, the
definite timer or the function itself, if desired.
4.2.5.4
Operation principle
The function can be enabled and disabled with the
Operation
setting. The corresponding
parameter values are Enable and Disable.
The operation of positive sequence undervoltage protection can be described by using a
module diagram. All the blocks in the diagram are explained in the next sections.
Figure 116:
Functional module diagram. V
1
is used for representing positive phase
sequence voltage.
Level detector
The calculated positive-sequence voltage is compared to the set Pickup value setting. If the
value goes below the set Pickup value, the level detector enables the timer. The Relative
hysteresis setting can be used for preventing unnecessary oscillations if the input signal
slightly varies from the Pickup value setting. After leaving the hysteresis area, the pickup
condition has to be fulfilled again and it is not sufficient for the signal to only return to the
hysteresis area.
The level detector contains a low level blocking functionality for cases where the positive
sequence voltage is below the desired level. This feature is useful when it is wanted to
avoid unnecessary starts and operates during, for example, an auto-reclose sequence. The
low level blocking is activated by default (
Enable block value
is set to “True”) and the
blocking level can be set with the
Voltage block value
setting.
Timer
Once activated, the timer activates the PICKUP output. The time characteristic is
according to DT. When the operation timer has reached the value set by
Trip delay
time,
the TRIP output is activated if the undervoltage condition persists. If the positivesequence
voltage normalizes before the module trips, the reset timer is activated. If the reset timer
reaches the value set by
Reset delay time
, the trip timer resets and the PICKUP output is
deactivated.
The timer calculates the pickup duration (PICKUP_DUR) value which indicates the ratio
of the pickup situation and the set trip time. The value is available through the Monitored
data view.
Содержание 615 Series ANSI
Страница 1: ...Relion Protection and Control 615 series ANSI Technical Manual ...
Страница 2: ......
Страница 29: ...1MAC050144 MB C Section 615 series ANSI 22 Technical Manual ...
Страница 389: ...Section 4 1MAC050144 MB C Protection functions 382 615 series ANSI Technical Manual ...
Страница 485: ...Section 6 1MAC050144 MB C Supervision functions 478 615 series ANSI Technical Manual ...
Страница 635: ...Section 10 1MAC050144 MB C Other functions 628 615 series ANSI Technical Manual ...
Страница 707: ...Section 15 1MAC050144 MB C Applicable standards and regulations 700 615 series ANSI Technical Manual ...
Страница 711: ...Section 16 1MAC050144 MB C Glossary 704 615 series ANSI Technical Manual ...
Страница 712: ......