13-50
Testing and Maintenance
BE1-951
Breaker Failure
Purpose: To verify the operation of the breaker failure (BF) function.
Reference Commands: SL-BF, SP-BF
Step 1
Prepare the BF function block for testing by transmitting the commands in Table 13-71 to the relay.
Table 13-71. BF Pickup Test Commands
Command
Purpose
A=
Gain write access
SL-N=NONE
Zero out custom logic settings. Overwrite with
logic=none settings.
Y
Confirm overwrite
SL-N=BF
Sets BF as custom logic name
SL-BF=1,IN4,/IN3
Enables BF, CT input 1, IN4 initiate, /IN3 block
SP-BF=50m
Set BF time delay at minimum
SL-VO1=BFT
Enables OUT1 to close for BF trip
SL-VO2=BFPU
Enables OUT2 to close for BF pickup
SG-CT=1
Sets P, N ct ratio at 1:1
SG-TRIGGER=BFT,BFPU,0
Enable BFT to log and trigger fault recording
EXIT;Y
Exit and save settings
Step 2 Energize relay inputs IN3 and IN4. This enables the BF logic and BF initiate.
The BF current detector pickup setting is a fixed value that is determined by the relay current
sensing type. Table 13-72 lists the pickup setting for each current sensing type.
Table 13-72. BF Current Detector Pickup Settings
Sensing Type
Pickup Setting
A or B (1 A)
0.1 A
D, E, or F (5 A)
0.5 A
Step 3 Connect a current source to terminals D1 and D2 (A-phase input). Slowly increase the current
applied to the A-phase input until OUT2 (and subsequently OUT1) closes. Compare the applied
current to the current values listed in Table 13-73. Verify that pickup occurred between the lower
and upper limits for your relay.
Table 13-73. BF Pickup Limits
Sensing Type
Lower PU Limit
Upper PU Limit
A or B (1 A)
0.09 A
0.11 A
D, E, or F (5 A)
0.45 A
0.55 A
Step 4 Transmit the commands in Table 13-74 to set the BF time delay.
