GE D90 Plus Instruction Manual page 169

CHAPTER 6: COMMUNICATIONS
Direct inputs and outputs for pilot-aides schemes
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
Path
IED 1 to IED 3
IED 1 to IED 4
IED 2 to IED 3
IED 2 to IED 4
IED 3 to IED 4
A coordinating timer for this bus protection scheme can be selected to cover the worst
case scenario (0.4 of a power system cycle). Upon detecting a broken ring, the coordination
time should be adaptively increased to 0.6 of a power system cycle. The complete
application requires addressing a number of issues, such as failure of both the
communications rings, failure, or out-of-service conditions of one of the IEDs. Self-
monitoring flags of the direct inputs and outputs feature is used to address these
concerns.
Consider the three-terminal line protection application shown.
Figure 137: Three-terminal line application
A permissive pilot-aided or blocking scheme can be accomplished using a dual-ring
configuration, shown as follows.
Figure 138: Dual-channel closed loop (dual-ring) configuration
Apply the following settings to implement this application. For all IEDs, set the inter-relay
application for both channels as follows in the Settings > Communications > Inter-Relay
menu.
DIRECT INPUTS AND OUTPUTS
Delivery time
0.4 of a power system cycle
0.6 of a power system cycle
0.2 of a power system cycle
0.4 of a power system cycle
0.6 of a power system cycle
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