L2275
Emax UL
67/132
Doc. N°
Mod.
RH0109002
Apparatus
Scale
Page N°
CB
Z
V
I
Inductive/resistive load
The zone selectivity function allows the fault area to be isolated, only isolating the installation to the level nearest the fault and keeping the rest
of the installation operational.
This means that a load side fault of “Relay 1a” will be isolated from the latter without “Relay 1” and “Relay 0” intervening. A fault just on the load
side of “Relay 1” will be isolated from the latter without “Relay 0” intervening, guaranteeing that the Areas 2…n remain active.
The ZSI signal can be connected up to 20 units in parallel (to the relative ZSO signal).
The ZSO output can be connected to a maximum of 3 ZSI relays on the supply side in the selectivity chain.
The maximum length of cabling for zone selectivity, between two units, is 300 meters.
Use corded shielded two-wire cable (see note A to par. 11.2.2).
The shield must only be grounded on the power circuit breaker of supply side relay (ZSI side).
Cabling and enabling zone selectivity “S” is an alternative to that of protection “D” and operation is only guaranteed when there is auxiliary voltage.
The following logical table is implemented to manage the Zone Selectivity Input (ZSI) and Zone Selectivity Output (ZSO) signals:
Zone selectivity
Imax > I2
ZSI Signal
ZSO signal
Trip t2 T
Excluded
N O
0
0
No trip
Excluded
N O
1
0
No trip
Excluded
YES
0
0
t2 programmed
Excluded
YES
1
0
t2 programmed
Inserted
N O
0
0
No trip
Inserted
N O
1
1
No trip
Inserted
YES
0
1
t
selectivity
Inserted
YES
1
1
t2 programmed
As seen in par.15.4.2.2, it is possible to set the time t
selectivity
(40... 200ms). The [tpgr] setting for the parameter makes t
selectivity
= t
2
(useful for the relays
at the base of the selectivity chain).
15.2.6.3
Directional Protection “D”
The PR113 unit carries out excludable directional protection against short circuit with adjustable fixed time (t = k) active both with self-supply and
with auxiliary supply.
The protection functionality is very similar to protection “S” with fixed time, with the capacity to recognize the current direction during the fault period
as well. However, it is a phase and not neutral protection.
The direction of the current allows determination of whether the fault is on the supply side or load side of the power circuit breaker. Especially in
ring distribution systems, this allows the distribution stretch where the fault occurred to be identified and to isolate it without interfering with the rest
of the installation (using zone selectivity).
The direction is only determined in the case where the maximum value of the phase reactive powers
is higher than 2% of the nominal phase power (
nfase
Q
P
P
⋅
≥
%
2
).
Once these conditions are fulfilled, the direction is defined in the following way:
!
positive reactive power
in
→
“forward” direction;
!
negative reactive power
in
→
“backward” direction.
In the drawing at the side, the direction of the current is
“forward” (PQ>0).
With regard to the trip times, it is possible to set two different ones [Bw, Fw] according to whether
the direction of the current trip selected is
“backward” or “forward”.
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