Basler Electric DGC-2020HD - Manual (Page 144)

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mains when a reclose occurs. If the generator is out of phase and connection with the mains is
established, damage could occur.
The vector shift element trips the breaker when it detects a phase shift in the generator voltage. A sudden
change in generator phase angle often occurs when the grid is lost. This change of phase angle results in
an earlier zero crossing of the generator voltage if the generator load decreases. It results in a later zero
crossing if the generator load increases. This shift of the zero crossing (vector shift) is expressed in
degrees.
Loss of mains protection is only active when the generator is paralleled to the mains as indicated when
the Parallel to Mains logic element is true in BESTlogicPlus. Protection is inhibited for five seconds after
the Parallel to Mains logic element first becomes true so that transients from closing onto the mains will
not cause false trips.
To minimize false trips, loss of mains protection is disabled if any configured breakers are not closed.
Vector shift trips are latched. They are cleared by pressing the Reset button on the front panel or by
putting the DGC-2020HD into Off mode.
Source
A Source setting configures the vector shift element to monitor the generator sensing input terminals or
the bus sensing input terminals.
Pickup and Trip
When the vector shift increases above the threshold established by the Pickup setting, the element Trip
output becomes true. In BESTlogicPlus, the Trip output can be connected to other logic elements or a
physical relay output to annunciate the condition and initiate corrective action.
Alarm Configuration
Vector shift annunciation can be user-selected to trigger a pre-alarm (warning) or alarm (shutdown). It can
also be user-configured to close a programmable output.
Element status is available in BESTlogicPlus programmable logic when “Status Only” is selected.
Open Mains Breaker or Gen Breaker on Trip
When Open Mains Breaker on Trip is enabled, the DGC-2020HD will request the mains breaker to open
when a 78 trip is annunciated. When Open Gen Breaker on Trip is enabled, the DGC-2020HD will request
the generator breaker to open when a 78 trip is annunciated.
Logic Connections
Vector shift element logic connections are made on the BESTlogicPlus screen in BESTCOMSPlus. The
vector shift element logic block is illustrated in Figure 73. When the Block input is true, the 78 element is
disabled. The Trip output is true when the 78 element is in a trip condition.
Figure 73. Vector Shift Element Logic Block
Operational Settings
Vector shift element operational settings are configured on the Vector Shift settings screen (Figure 74) in
BESTCOMSPlus. Setting ranges are defined in the Specifications chapter.
Generator Protection DGC-2020HD