Functions
6-78 7SJ62 Manual
C53000-G1140-C121-1
Generation of a tripping message, for both current and voltage elements, is dependent
on the direction selection for each element. If the element is set to QRQGLUHFWLRQ
DO, then exceeding the current element pickup setting causes a corresponding mes-
sage, independent of the condition of the V
0
element. But, if a direction is pro-
grammed, the current element must be picked up and the direction determination re-
sults must be present to generate a message. Once again, a condition for valid direc-
tion determination is that the voltage element be picked up as well.
Based on the setting at address 38&5,7(5,$, the generation of a fault condi-
tion message can be dependent on either the pickup of both the voltage and current
elements (AND function), or a pickup of at least one of those two elements (OR func-
tion). The former may be advantageous if the pickup setting of the voltage element
was chosen to be very low.
6.6.1.4 Location of Ground Connections
Application
Example
Directional determination may often be used to locate a grounded connection. In radial
systems, locating the ground connection is relatively simple. Since all feeders from a
common bus (Figure 6-36) deliver a capacitive charging current, practically the same
ground connection current is available at the relay location of a faulted feeder in an
ungrounded system. In a looped system, the relay locations of the faulted line receive
the maximum ground connection current. “Forward” is reported at both ends only for
the faulted line (Figure 6-37), However, the other directional indicators in the system
may also be of help, if not missing due to insufficient ground current.
Figure 6-36 Location of a Ground Fault in a Radial System
www . ElectricalPartManuals . com
To Next Page
Loading...
Need help?
General