P.9.3
Date Code 20151029 Protection Manual SEL-411L Relay
Monitoring and Metering
Circuit Breaker Monitor
Circuit Breaker
Contact Wear Monitor
The circuit breaker contact wear monitor in the relay provides information
that helps you schedule circuit breaker maintenance. This monitoring function
accumulates the number of close-open operations and integrates the per-phase
current during each opening operation. The relay compares this information to
a predefined circuit breaker maintenance curve to calculate the percent contact
wear on a per-pole basis.
The circuit breaker maintenance curve also incorporates the accumulated fault
current arcing time (I
2
t), assuming an identical arcing time for each trip. You
can obtain the one-cycle arcing time from circuit breaker manufacturer data.
The relay updates and stores the contact wear information and the number of
trip operations in nonvolatile memory. You can view this information through
any communications port.
Any phase wear percentage that exceeds the threshold setting B1BCWAT
asserts the alarm Relay Word bit, B1BCWAL, for Circuit Breaker 1. You can
use this Relay Word bit in a SEL
OGIC
®
control equation to alert operations
personnel, or you can control other functions such as blocking reclosing. The
relay clips or limits the maximum reported circuit breaker wear percentage at
150 percent.
NOTE: In the following discussion,
three elements are specified, one for
each phase: A, B, and C).
The relay integrates currents and increments the trip counters for the contact
wear monitor each time the SEL
OGIC control equation BM1TRP asserts. Set
the logic for this function from a communications port with the SET M ASCII
command, with the
ACSELERATOR QuickSet
®
SEL-5030 software program
Breaker Monitor Settings tree view, or by using the front-panel
SET/SHOW
menu. (See Making Simple Settings Changes on page P.10.13 for information
on setting the relay using these methods.) The default settings cause the
contact wear monitor to integrate and increment each time the relay trip logic
asserts.
Using the Circuit Breaker Contact Wear Monitor
Perform the following specific steps to use the circuit breaker contact wear
monitor:
Step 1. Enable the circuit breaker monitor.
Step 2. Load the manufacturer’s circuit breaker maintenance data.
Step 3. Preload any existing circuit breaker wear (if setting up the
contact wear monitor on a circuit breaker with preexisting
service time).
Step 4. Program the SEL
OGIC control equations for trip and close
conditions.
Enable the Circuit Breaker Monitor
You must enable the circuit breaker monitor before you load the
manufacturer’s data, preload any existing circuit breaker wear, and set the trip
initiate and close initiate SEL
OGIC control equations. Set the circuit breaker
monitor enable setting EB1MON to Y (for Yes). You can set EB1MON by
using ASCII command SET M, the
ACSELERATOR QuickSet Breaker
Monitor branch of the Settings tree view, or with the front-panel
SET/SHOW
submenu.
Load Manufacturer Circuit Breaker Maintenance Data
Load the maintenance data supplied by the circuit breaker manufacturer.
Circuit breaker maintenance information lists the number of permissible
operating cycles (close/open operations) for a given current interruption level.
NOTE: If you want to enable the
circuit breaker monitor on Circuit
Breaker 2, confirm that the relay is set
for two-circuit breaker operation;
setting NUMBK must be 2. Once you
have set NUMBK := 2, you can set the
Circuit Breaker 2 monitor settings,
including EB2MON.
To Next Page
Loading...
