Schweitzer Engineering Laboratories SEL-311C - Directional Comparison Blocking Logic; External Inputs; Timer Settings

5.25
Date Code 20060320 Instruction Manual SEL-311C Relay
Trip and Target Logic
Directional Comparison Blocking Logic
Directional Comparison Blocking Logic
Enable the directional comparison blocking (DCB) logic by setting ECOMM
= DCB. The DCB logic in Figure 5.14 performs the following tasks:
➤ Provides the individual carrier coordination timers for the Level
2 directional elements M2P, Z2G, 67G2, and 67Q2 via the
Z2PGS and 67QG2S Relay Word bits. These delays allow time
for the block trip signal to arrive from the remote terminal. For
example:
TRCOMM = Z2PGS + 67QG2S
➤ Instantaneously keys the communications equipment to
transmit block trip for reverse faults and extends this signal for
a settable time following the dropout of all Level 3 directional
elements (M3P, Z3G, 67G3, and 67Q3).
➤ Latches the block trip send condition by the directional
overcurrent following a close-in zero-voltage three-phase fault
where the polarizing memory expires. Latch is removed when
the polarizing memory voltage returns or current is removed.
➤ Extends the received block signal by a settable time.
Use Existing SEL-321
DCB Application
Guide for the
SEL-311C
Use the existing SEL-321 DCB application guide (AG93-06) to help set up the
SEL-311C in a DCB scheme (see Communications-Assisted Trip
Logic-General Overview on page 5.10 for more setting comparison
information on the SEL-321/SEL-311C relays).
External Inputs
See Optoisolated Inputs on page 7.3 for more information on optoisolated
inputs.
BT—Received Block Trip Signal(s)
In two-terminal line DCB applications, a block trip signal is received from
one remote terminal. One optoisolated input on the SEL-311C (e.g., input
IN104) is driven by a communications equipment receiver output (see
Figure 5.15). Make SEL
OGIC control equation setting BT:
BT = IN104 (two-terminal line application)
In three-terminal line DCB applications, block trip signals are received from
two remote terminals. Two optoisolated inputs on the SEL-311C (e.g., inputs
IN104 and IN106) are driven by communications equipment receiver outputs
(see Figure 5.16). Make SEL
OGIC control equation setting BT as follows:
BT = IN104 + IN106 (three-terminal line application)
SEL
OGIC control equation setting BT is routed through a dropout timer
(BTXD) in the DCB logic in Figure 5.14. The timer output, Relay Word bit
BTX, is routed to the trip logic in Figure 5.1.
Timer Settings
See Section 9: Setting the Relay for setting ranges.