GE L60 Instructions Manual page 685

CHAPTER 9: THEORY OF OPERATION
Single pole operations are based on use of the phase selector to identify the type of the fault, to eliminate incorrect fault
identification that can be made by distance elements in some circumstances and to provide trip initiation from elements
that are not capable of any fault type identification, such as high-set negative-sequence directional overcurrent element.
The scheme is also designed to make use of the advantages provided by communications channels with multiple-bit
capacities for fault identification.
The trip output element receives requests for single and three-pole trips and three-pole reclose initiation, which it then
processes to generate outputs that are used to
• Determine whether a single or three-pole operation is to be performed
• Initiate tripping of breaker poles A, B, and C, either individually or as a group
• Initiate breaker failure protection for phases A, B, and C, either individually or as a group
• Notify the open pole detector when a single pole operation is imminent
• Initiate either single or three-pole reclosing
• Notify the phase selector when a trip operation is imminent
When notified that a single pole operation has been initiated, the open-pole detector
• Initiates blocking of protection elements that can potentially maloperate when a breaker pole is open
• Instructs the phase selector to de-assert all outputs, as an open pole invalidates calculations
L60 LINE PHASE COMPARISON SYSTEM – INSTRUCTION MANUAL
Figure 9-28: Single-pole operation
SINGLE-POLE TRIPPING
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