GE L60 Instruction Manual page 150

5.2 PRODUCT SETUP
IED 1 to IED 2: 0.2 of power system cycle; IED 1 to IED 3: 0.4 of power system cycle;
IED 1 to IED 4: 0.6 of power system cycle; IED 2 to IED 3: 0.2 of power system cycle;
IED 2 to IED 4: 0.4 of power system cycle; IED 3 to IED 4: 0.2 of power system cycle
A coordinating timer for this bus protection scheme could be selected to cover the worst case scenario (0.4 of power sys-
tem cycle). Upon detecting a broken ring, the coordination time should be adaptively increased to 0.6 of 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 relays, etc. Self-monitoring flags of the direct inputs/outputs feature would
5
be primarily used to address these concerns.
EXAMPLE 3: PILOT-AIDED SCHEMES
Consider the three-terminal line protection application shown below:
A permissive pilot-aided scheme could be implemented in a two-ring configuration as shown below (IEDs 1 and 2 constitute
a first ring, while IEDs 2 and 3 constitute a second ring):
In the above application, the following settings should be applied:
UR IED 1:
DIRECT OUTPUT DEVICE ID:
DIRECT I/O RING CONFIGURATION:
UR IED 3:
DIRECT OUTPUT DEVICE ID:
DIRECT I/O RING CONFIGURATION:
In this configuration the following delivery times are expected (at 128 kbps):
IED 1 to IED 2: 0.2 of power system cycle; IED 1 to IED 3: 0.5 of power system cycle;
IED 2 to IED 3: 0.2 of power system cycle
In the above scheme, IEDs 1 and 3 do not communicate directly. IED 2 must be configured to forward the messages as
explained in the Inputs/Outputs section. A blocking pilot-aided scheme should be implemented with more security and, ide-
ally, faster message delivery time. This could be accomplished using a dual-ring configuration as shown below.
5-48
UR IED 1
Figure 5–10: THREE-TERMINAL LINE APPLICATION
TX1
UR IED 1
RX1
UR IED 3
Figure 5–11: SINGLE-CHANNEL OPEN LOOP CONFIGURATION
"1"
"Yes"
"3"
"Yes"
L60 Line Phase Comparison Relay
UR IED 2
UR IED 3
842713A1.CDR
RX1 RX2
UR IED 2
TX1 TX2
RX1
TX1
842714A1.CDR
UR IED 2:
DIRECT OUTPUT DEVICE ID:
DIRECT I/O RING CONFIGURATION:
5 SETTINGS
"2"
"Yes"
GE Multilin