9424200996 84-29
BE1-11m Settings Calculation Examples
Ground CT Ratios
This large synchronous motor is solidly grounded (to be most effective in power factor management. This
application uses the residual current calculated in the BE1-11m to detect ground faults. No CT ratio must
be entered in this case; leave the default at 1 on the System Parameters, Sensing Transformers screen
shown in Figure 84-35.
Phase VT Setup
In this example, the phase VT connection is 3-wire, delta. The system voltage is 12 kV. The phase VT
ratio is calculated in Equation 84-22.
=
12000
120
= 100
Equation 84-22. Phase VT Ratio
Use the Settings Explorer in BESTCOMSPlus to navigate to the System Parameters, Sensing
Transformers screen shown in Figure 84-35. Set Phase VT Ratio to 100 and set Phase VT Connection to
3W-D.
The 27 and 59 elements will remain set in primary phase-to-phase quantities, as well as the 27R Mode.
The single-phase input is not used in this application settings example so the Auxiliary VT Setup can
remain unchanged. The Bus CT Selection is the motor incoming power from the bus on CT1 source.
Figure 84-35. System Parameters, Sensing Transformers Screen
System Parameters - Motor Configuration
Nominal Settings
The system nominal quantities are used for BE1-11m functions such as the 60FL (loss of VT fuse). Enter
all nominal settings in phase-to-neutral quantities and secondary quantities (required by the BE1-11m) on
the System Parameters, Motor Configuration screen shown in Figure 84-36. The BE1-11m Nominal
Settings must be set for secondary units.
Motor Setup
The motor FLA and Service Factor must be entered on the System Parameters, Motor Configuration
screen shown in Figure 84-36. These settings are used by the BE1-11m for thermal model calculations
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