Programmable Contact Outputs Applications; Breaker Failure Protection - ABB REL 301 Instruction Leaflet

INSERT key. T for logic true or F for logic Negation will show at that position. If is desired to
remove the selection, the DELETE key can be used to de-select a previously selected function.
If a contact is to be controlled by several functions, the same procedure applies for each func-
tion, without forgetting the combining operator OR or AND, shown at the beginning of each con-
tact line.
Time Delay Pickup and Dropout. To set the timers, move the cursor to the desired timer, lo-
cated beneath the contact output
the upper right corner of the screen and can be adjusted with the Up or Down direction keys
followed by ENTER when the desired time is displayed. Timer setting selection can be acceler-
ated by using the Page Up and Page Down direction keys. Each timer can be set from 0 - 2000
cycles in 1 cycle increments.
4.10.1

Programmable Contact Outputs Applications

4.10.1.1

Breaker Failure Protection

A Breaker Failure Scheme Using REL 301/302 programmable outputs and internally derived
overcurrent signals is described in the following. The REL 301/302's programmable logic capa-
bilities permit its use in this application. The scheme can be simple, two contacts with time de-
lays BF1 and BF2, or more complex using the two contacts mentioned plus one contact (OC1)
as a Retrip and another contact, with time delay, as the control timer function. A simple scheme
is described below.
1. Operation
When a breaker failure initiate (BFI) is detected via the P52a input, in conjunction with an over-
current signal (IM or IOM), the pickup delay timers called BF1 and BF2 begin timing. Separate
BF timers are used to allow individual settings for phase and ground faults. The breaker failure
times should allow ample margin to give the breaker an opportunity to interrupt the current and
clear.
Normal Clearing
Normal Clearing Time
RELAY BKR INTERRUPT
BFI
Inoperative Breaker
At the end of the pickup time delay, BF1 or BF2, if P52a and the overcurrent signals are still
present, the breaker failure lockout 86BF will operate via programmable output OC3 or OC4
(see Figure 4-4). Transfer tripping, if applied, would then operate appropriate remote breakers
Breaker Failure Timing Diagram
Margin
BF1 & 2 TIMERS
CONTROL TIMER
table and press ENTER. The value to be set is displayed in
Backup Breaker Failure Total Clear Time
86BF LOCAL BACKUP CLEARING
TT
I.L. 40-386.4
Local Remote
REMOTE BACKUP CLEARING
CT R
4-11