Basler Electric BE1-11g - Manual (Page 112)

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When single-phase voltage sensing is used, only the inverse overcurrent element on the phase with
voltage magnitude information is affected by the 51/27R feature. Thus, in voltage control mode, the 51
elements on the two unmonitored phases will always be disabled. In voltage restraint mode, the 51
elements on the two unmonitored phases will not have their overcurrent pickup settings adjusted from
100%.
Element Blocking
Fuse Loss
The fuse loss element (60FL) can also be set to supervise the 51/27R function. It is possible to set the
60FL element to automatically prevent misoperation on loss of sensing voltage. When the 51/27R
function is set for control and a 60FL condition is detected, the inverse overcurrent elements will be
disabled. When the 51/27R function is set for restraint and a 60FL condition is detected, the inverse
overcurrent elements will remain enabled but the pickup will not be adjusted from 100% of its setting. See
the
Fuse Loss (60FL) chapter for more information.
Protective elements blocked by 60FL should be set so that trip times are 60 milliseconds or greater to
assure proper coordination of blocking.
Block Logic Input
The Block input provides logic-supervision control of the element. When true, the Block input disables the
element by forcing the Trip and Pickup outputs to logic 0 and resetting the element timer. Connect the
element Block input to the desired logic in BESTlogicPlus. When the element is initially selected from the
Elements view, the default condition of the Block input is a logic 0.
Logic Connections
Inverse overcurrent element logic connections are made on the BESTlogicPlus screen in
BESTCOMSPlus. The inverse overcurrent element logic block is illustrated in Figure 64. Logic inputs and
outputs are summarized in Table 35.
Figure 64. Inverse Overcurrent Element Logic Block
Table 35. Logic Inputs and Outputs
Name Logic Function Purpose
Block Input Disables the 51 function when true
Trip Output True when the 51 element is in a trip condition
Pickup Output True when the 51 element is in a pickup condition
Operational Settings
Inverse overcurrent element operational settings are configured on the Inverse Overcurrent (51) settings
screen (Figure 65) in BESTCOMSPlus. Setting ranges and defaults are summarized in Table 36.
Inverse Overcurrent (51) Protection BE1-11g