Siemens SIPROTEC 7UT613 series Manual page 320

2 Functions
Function Setting
320
and the voltages assigned to the currents. Power functions are only possible if the
device has voltage inputs.
Set the measuring type for the power functions. Please note that this option has a re-
spectively higher operating time due to the averaging over 16 periods. Short trip times
are possible with this option as the power is determined over one period only. If also
small active or reactive power must be calculated from bigger apparent power, this
option is preferred and the phase-angle errors of the current and voltage transformers
must be compensated by means of the respective setting of the error angle in address
803 CORRECT. U Ang (section 2.1.4).
Irrespective of which measuring value or calculated value was supposed to be deter-
mined by a flexible function, determine under Pickup whether the function is supposed
to pick up on exceeding or undershooting the limit value, which shall be set at a later
stage.
Under Function a flexible function can be activated or deactivated. If message only
is set, this function only triggers a message and not a trip command. The command
can be blocked if the function is activated (block. relay).
Enter the pickup value pickup threshold in a suitable dimension for the function. The
dimension automatically appears in accordance with the above configured specifica-
tions of the evaluated value. The setting with regard to whether the limit value is to be
monitored on exceeding or undershooting, has already been determined by the con-
figuration settings.
The pickup and the drop-off of the fault detection can be delayed. Delay of the pickup
means that after non-compliance with the limit value condition, this period must first
expire before a pickup can be indicated and result in further actions. Delay of the
drop-off means that, after activated pickup, same can be maintained and delayed by
such time period after non-compliance of the limit value has stopped.
The trip command (if desired) is thus delayed by means of the trip command delay.
The time starts on activation of the pickup (if necessary, also after time delay). Please
note that the command delay must be set in such manner that it is significantly longer
than a possibly set reset delay. Otherwise, every pickup will result in a trip because
the pickup for the reset delay is maintained, although the criterion to be monitored is
no longer complied with.
Please also note that the set times are pure additional delays that do not include the
inherent operating time of the function (functional internal pickup and drop-off times).
This has an effect especially on accurate power functions as these carry out measure-
ments over 16 network period.
The dropout ratio can be set to wide ranges. If functions react on exceeding a limit
value, such value is smaller than 1; if the functions that react on undershooting the limit
value, such value is greater than 1. The possible setting range is automatically deter-
mined in accordance with the function, which has either been configured to exceeding
or undershooting.
The drop-out ratio to be set depends on the application. In general, it can be stated
that: the limit value must be closer to 1 the lesser the pickup value differs from the op-
erating valid values. Latching of the pickup due to short-term fluctuations of the mea-
sured values during operation must be avoided.
Conversely, the drop-out ratio should not be set more sensitive (closer to 1) than nec-
essary, thus avoiding an intermitting pickup to be caused in conditions close to the
pickup value.
7UT613/63x Manual
C53000-G1176-C160-2