Sel SEL-421 - One-Circuit-Breaker Auto-Reclosing; One Circuit Breaker Auto-Reclose Modes

R.2.4
SEL-421 Relay Reference Manual Date Code 20111215
Auto-Reclosing and Synchronism Check
One-Circuit-Breaker Auto-Reclosing
paths between two states indicate the logic can move in either direction
between the two states. The dashed vertical line that runs through the center of
the figure indicates the states common to both circuit breakers.
Tab le 2.1 describes each of the five states with respect to Circuit Breaker 1,
along with the corresponding Relay Word bits.
Figure 2.1 Auto-Reclose State Diagram for Circuit Breaker 1
One-Circuit-Breaker Auto-Reclosing
One Circuit Breaker
Auto-Reclose Modes
The SEL-421 auto-reclose logic operates in three modes:
➤ Single-pole mode (SPAR)
➤ Three-pole mode (3PAR)
➤ Single- and three-pole mode (SPAR/3PAR)
Relay settings ESPR1 (Single-Pole Reclose Enable—BK1) and E3PR1
(Three-Pole Reclose Enable—BK1) determine the auto-reclose mode (see
Recloser Mode Enables on page R.2.9). These settings are inputs to the
recloser initiation Relay Word bits SPARC (Single-Pole Reclose Initiate
Qualified) and 3PARC (Three-Pole Reclose Initiate Qualified); see Figure 2.8
and Figure 2.9. SPARC asserts when all necessary conditions to begin a
single-pole auto-reclose cycle are satisfied (ESPR1, for example) and the
recloser receives a single-pole reclose initiation SPRI (see Figure 2.8).
Table 2.1 Auto-Reclose Logical States for Circuit Breaker 1
State Description Relay Word Bit
Start Power up, or relay settings
change
79STRT
Reset Circuit Breaker 1 reset BK1RS
Single-pole auto-reclose cycle Single-pole auto-reclose 79CY1
Three-pole auto-reclose cycle Three-pole auto-reclose cycle 79CY3
Lockout Lockout BK1LO
79CY1
79CY3
79STRT
BK1LO
Breaker 1
Reset or
Ready
Breaker 1
Lockout
1-Pole
Auto-Reclose
Start
3-Pole
Auto-Reclose
BK1RS