Toshiba GRL100-701B Instruction Manual page 104

Scheme Logic
Figure 2.10.3 shows the scheme logic of the broken conductor protection. BCD element outputs
trip signals BCD TRIP through a delayed pick-up timer TBCD.
The tripping can be disabled by the scheme switch [BCDEN] or binary input signal BCD
BLOCK.
635
BCD
[BCDEN]
+
"ON"
BCD BLOCK
1
Figure 2.10.3 Broken Conductor Protection Scheme Logic
Settings
The table below shows the setting elements necessary for the broken conductor protection and
their setting ranges.
Element Range
BCD 0.10 – 1.00
TBCD 0.00 – 300.00s
[BCDEN] Off / On
Minimum setting of the BC threshold is restricted by the negative phase sequence current
normally present on the system. The ratio I
continuously and displayed on the metering screen of the relay front panel, along with the
maximum value of the last 15 minutes I
commissioning stage. The BCD setting should be 130 to 150% of I
Note: It must be noted that I
(or load current) in the secondary circuit is larger than 2 % of the rated secondary circuit
current.
TBCD should be set to more than 1 cycle to prevent mal-operation caused by a transient
operation such as CB closing.
TBCD
t
&
0.00 - 300.00s
Step Default Remarks
0.01 0.20 I / I
2 1
0.01s 1.00 s BCD definite time setting
Off BCD Enable
/ I of the system is measured in the relay
2 1
max. It is recommended to check the display at the
21
/ I is displayed only when the positive phase sequence current
2 1
 103 
0
859
BCD TRIP
/ I displayed.
2 1
6 F 2 S 0 8 5 0