Siemens siprotec SJ62 User Manual page 265

2 Functions
Function Logic
Blocking Functions
Operating Mode,
Measured Quantity,
Measurement
Method
Characteristic
Curve
263
The maximum 20 configurable protection functions operate independently of each
other. The following description concerns one function; it can be applied accordingly
to all other flexible functions. The logic diagram 2-90 illustrates the description.
The function can be switched ON and OFF or, it can be set to Alarm Only. In this
status, a pickup condition will neither initiate fault recording nor start the trip time delay.
Tripping is thus not possible.
Changing the Power System Data 1 after flexible functions have been configured may
cause these functions to be set incorrectly. Message (FNo. 235.2128 „$00
inval.set") reports this condition. The function is inactive in this case and function's
setting has to be modified.
The function can be blocked via binary input (FNo. 235.2110 „>BLOCK $00") or via
local operating terminal („Control" -> „Tagging" -> „Set"). Blocking will reset the func-
tion's entire measurement logic as well as all running times and indications. Blocking
via the local operating terminal may be useful if the function is in a status of permanent
pickup which does not allow the function to be reset. In context with voltage-based
characteristics, the function can be blocked if one of the measuring voltages fails. Rec-
ognition of this status is either accomplished by the relay's internal „Fuse-Failure-Mon-
itor" (FNo. 170 „VT FuseFail"; see chapter 2.11.1) or via auxiliary contacts of the
voltage transformer CB (FNo. 6509 „>FAIL:FEEDER VT" and FNo. 6510 „>FAIL:
BUS VT"). This blocking mechanism can be enabled or disabled in the according pa-
rameters. The associated parameter BLK.by Vol.Loss is only available if the charac-
teristic is based on a voltage measurement.
When using the flexible function for power protection or power monitoring, it will be
blocked if currents fall below 0.03 I
The flexible function can be tailored to assume a specific protective function for a con-
crete application in parameters OPERRAT. MODE, MEAS. QUANTITY, MEAS.
METHOD and PICKUP WITH. Parameter OPERRAT. MODE can be set to specify
whether the function works 3-phase, 1-phase or no reference, i.e. without a
fixed phase reference. The three-phase method evaluates all three phases in parallel.
This implies that threshold evaluation, pickup indications and trip time delay are ac-
complished selectively for each phase and parallel to each other. This may be for
example the typical operating principle of a three-phase time overcurrent protection.
When operating single-phase, the function employs either a phase's measured quan-
tity, which must be stated explicitly, (e.g. evaluating only the current in phase Ib), the
measured ground current In or the measured displacement voltage Vn. If the charac-
teristic relates to the frequency or if external trip commands are used, the operating
principle is without (fixed) phase reference. Additional parameters can be set to
specify the used MEAS. QUANTITY and the MEAS. METHOD. The MEAS. METHOD
determines for current and voltage measured values whether the function uses the
rms value of the fundamental component or the normal r.m.s. value (true RMS) that
evaluates also harmonics. All other characteristics use always the rms value of the
fundamental component. Parameter PICKUP WITH moreover specifies whether the
function picks up on exceeding the threshold (>-element) or on falling below the
threshold (<-element).
The function's characteristic curve is always „definite time"; this means that the delay
time is not affected by the measured quantity.
.
Nom
SIPROTEC 4, 7SJ62/63/64 Handbuch
C53000-G1140-C147-A, Edition 07.2015