8.3
Date Code 20171006 Instruction Manual SEL-400 Series Relays
Monitoring
Circuit Breaker Monitor
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 limits the
maximum reported circuit breaker wear percentage to 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 Moni-
tor Settings tree view, or by using the front-panel
SET/SHOW menu. (See Making
Simple Settings Changes on page 3.15 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.
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
EBxMON to Y (for Yes) for Breaker x.
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. Tabl e 8 .2 shows
typical circuit breaker maintenance information from an actual SF6 circuit
breaker. The Figure 8.2 log/log plot is the circuit breaker maintenance curve, pro-
duced from the Table 8.2 data.
Table 8.2 Circuit Breaker Maintenance Information—Example (Sheet 1 of 2)
Current Interruption Level (kA) Permissible Close/Open Operations
0.00–1.2 10000
2.00 3700
3.00 1500
5.00 400
8.00 150
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