Basler BE1-11m - Page 89

9424200996 14-5
BE1-11m Inverse Overcurrent (51) Protection
Figure 14-2. 51 Phase Pickup Level Compensation
   =
  
  
× 51 ℎ  
Equation 14-3. Restraint Pickup Level
Phase VT Configuration
The 51/27R function can be set to monitor either Vpp or Vpn depending upon the Phase VT Connection
settings. See the Configuration chapter for details on how to set the phase VT connections. Table 14-2
shows which voltage measurements are used by each 51 element for each possible phase VT connection
and 51/27 voltage monitoring mode setting.
Table 14-2. Phase VT Connection Cross Reference
Phase VT Connection
51/27 Mode
51A
51B
51C
4W
Vpp
Vab
Vbc
Vca
4W
Vpn
Van
Vbn
Vcn
3W
Vpp
Vab
Vbc
Vca
AN
Vpn
Van
Vbn*
Vcn*
BN
Vpn
Van*
Vbn
Vcn*
CN
Vpn
Van*
Vbn*
Vcn
AB
Vpp
Vab
Vbc*
Vca*
BC
Vpp
Vab*
Vbc
Vca*
CA
Vpp
Vab*
Vbc*
Vca
* Calculated value. See the Configuration chapter for more information.
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.