Output Contact Test; Out-Of-Step Block Logic; Subsequent Out-Of-Step Security Logic - ABB REL 301 Instruction Leaflet

I.L. 40-386.4
2.4.15

Output Contact Test

A "Push-to-Close" feature is included in order to check all output relay contacts, which include
TRIP, BFI, RI2, RB, AL1, AL2, GS, Carrier Send (Pilot), Carrier Stop (Pilot) and each program-
mable contact output (if supplied). The relay contact check is supplementary to the self-check
because the Microprocessor self-check routine cannot check the output hardware. In order to
enable the contact test, jumper JP5 on the Microprocessor module must be in place. (See Sec-
tion 5.1.7 for detailed procedures.)
2.4.16 Out-of-Step Block Logic (Figures 2-19a & 2-19b)
The Out-of-Step Blocking (OSB) logic (power swing block supervision) in REL301/302 is a dou-
ble blinder scheme. It contains two blinder units, providing 4 blinder lines. (See Figure 2-19b.)
The nature of the logic (shown in Figure 2-19a) is that the outer blinder 21BO must operate
50ms or more ahead of the inner blinder 21BI, in order for an OSB condition to be identified.
Blinder reaches are determined by the setting of "OS Inner" and "OS Outer", respectively. The
OSB signal is a negated input to the AND 131 (Z1P), AND 147 (Z2P), AND 160 (Z3P), and AND
176 (PLTP) for supervising the 3-phase distance tripping. In addition to controlling the OSB log-
ic, the blinder units are also used to supervise distance relay tripping (Load Restriction). Phase
distance unit tripping cannot take place unless 21BI operates. This prevents operation of the dis-
tance relay on load. The OSB signal is also applied to the reclosing logic for initiating RB.
The following quantities are used for the blinder sensing:
where
V XG
I X
R
"Ang Pos." =
Operation occurs if the operating voltage leads the polarizing voltage. The characteristics are
as shown in Figure 2-19b.
2.4.16.1

Subsequent Out-of-Step Security Logic

Model power system tests, when using a motOR generatOR set, show that the Zone-1 imped-
ance unit may overreach or respond to a reversed fault. This was attributed to motOR generator
set instability following delayed clearing on an external fault. The Zone-1 relay, in all cases, iden-
tified the fault location and type correctly and responded much later to the swing condition.
Logic was added, OR 131A, AND 131B, AND 131C and OR 122A, utilizing the inner blinder and
Zone-1 sensing sequence, plus a 50 millisecond timer (as shown in Figure 2-19a) to differenti-
ate between a fault and a subsequent out-of-step condition. This logic will not affect normal
Zone-1 trip time, nor will it affect normal out-of-step blocking.
2-12
Blinder
Line
Left -j(V XG + I X R C (
Right j(V XG - I X R C (
= Phase to ground voltage, V A G or V BG
= Phase current in ØA or ØB
= Setting of the unit "OS Inner" for 21BI (R
C
(R ).
U
The positive sequence line impedance angle.
Polarizing
°
Ang Pos.
–90 ) I X (
°
Ang Pos.
–90 ) I X (
Operating
°
Ang Pos.
–90 )
°
Ang Pos.
–90 )
)or "OS Outer" for 21BO
T