Basler Electric BE1-11g - Manual (Page 61)

9424200994 Rev N 49
Sync-Check (25) Protection
The sync-check (25) element provides breaker closing supervision by comparing the voltage magnitude,
angle, and frequency of the phase voltage to the voltage magnitude, angle, and frequency of the auxiliary
voltage to determine synchronism. This element is not available in styles GxxxxxxxSxxxxx and
GxxxxxJxTxxxxx.
Element logic connections are made on the BESTlogic
™Plus screen in BESTCOMSPlus® and element
operational setting are configured on the Sync-Check settings screen in BESTCOMSPlus. A summary of
the logic inputs and outputs and operational settings appears at the end of this chapter.
BESTCOMSPlus Navigation Path: Settings Explorer, Protection, Voltage, Sync-Check (25)
HMI Navigation Path: Settings Explorer, Protection, Settings Group x (where x = 0 to 3), Voltage
Protection, Sync Check 25
Element Operation
When monitored voltage between the sources meets angle, voltage, and slip criteria, the element Sync
output becomes true. In BESTlogicPlus, the Sync output can be connected to other logic elements to
annunciate the condition or control other elements in logic. The Sync logic output becomes true when all
three of the following conditions are met:
1. Phase angle between sources is less than the Slip Angle setting.
2. Frequency error between sources is less than the Slip Frequency setting. (Note: When the
Source Freq > Destination Freq setting box is checked, only generator frequency greater than
bus frequency is allowed.)
3. Voltage magnitude between sources is less than setting. (Note: The voltage used by the BE1-11g
for this feature is a voltage magnitude measurement, not a voltage phasor measurement.)
Voltage thresholds are entered in percent allowing the use of non-equal transformers with the sync-check
function. The sync-check element Sync logic output is true when the criteria are met for the entered
nominal bus voltage, nominal line voltage, and allowable percent difference. For example, the sensing for
the generator is on one side of a step-down transformer and the sensing for the bus is on the other.
Dead/Live values are entered as percent as well.
Note
The sync-check function will not work if VTX connections are set for
residual voltage input.
Measuring slip frequency directly allows the sync-check element to rapidly determine if systems are in
synchronism and requires no timer or inherent delay (as compared to systems that check only that the
phase angle is held within a window for some stretch of time). The moment that conditions 1, 2, and 3
(listed above) are met, the systems can be considered in synchronism, and the Sync logic output
becomes true. Refer to the Metering chapter for more information about slip frequency measurement.
VT Connections
The sync-check element compares the phase (generator) voltage to the auxiliary (bus) voltage. Proper
connection of the voltage transformer inputs is vital for correct operation of the sync-check element.
For clarification on single-phase VTP connections, refer to the Typical Connections chapter. The single-
phase parallel connections ensure that the zero-crossing circuit is always connected to the sensed circuit.
For single-phase sensing connections derived from a phase-to-neutral source:
BE1-11g Sync-Check (25) Protection