Siemens SIPROTEC Manual page 159

If the device is provided with the capability to trip single-pole, single-pole tripping is then possible in the zones
Z1 and Z2. While single-pole tripping usually applies to single-phase faults in Z1 (if the remaining conditions
for single-pole tripping are satisfied), this may also be selected for the second zone with address 1617 Trip
1pole Z2. Single pole tripping in zone 2 is only possible if this address is set to YES. The default setting is NO.
Note
For instantaneous tripping (undelayed) in the forward direction, the first zone Z1 should always be used, as
only the zone Z1 and Z1B are guaranteed to trip with the shortest operating time of the device. The further
zones should be used sequentially for grading in the forward direction.
If instantaneous tripping (undelayed) is required in the reverse direction, the zone Z3 should be used for this
purpose, as only this zone ensures instantaneous pickup with the shortest device operating time for faults in
the reverse direction. This setting is also recommended in teleprotection BLOCKING schemes.
With the binary input indications 3619 „>BLOCK Z4 Ph-E" and 3620 „>BLOCK Z5 Ph-E" and 3622
„>BLOCK Z6 Ph-E", the zones Z4, Z5 and Z6 can be blocked for phase-to-earth loops. To block these zones
permanently for phase-to-earth loops, these binary input indications must be set permanently to the logic value
of 1 via CFC.
Zone Z5 is preferably set as a non-directional final stage. It should include all other zones and also have suffi-
cient reach in reverse direction. This ensures adequate pickup of the distance protection in response to fault
conditions and correct verification of the short-circuit loops even under unfavourable conditions.
Note
Even if you do not need a non-directional distance stage, you should set Z5 according to the above aspects.
Setting T5 to infinite prevents that this stage causes a trip.
Blocking of Zone Z1
If the main protection functions - differential protection and distance protection - operate in parallel, the distance
protection of Zone Z1 may pick up before the differential protection (e.g. in the case of close-up faults). If this
is desired, the distance protection works as a „booster" stage for fast tripping. If the fast tripping acts on one
end of the line only, accelerated tripping of zone Z1 is not desired (see also Section 2.5.1.4).
There are two ways of blocking Z1. If the device operates in differential protection mode, zone Z1 can be
blocked by setting a parameter (address 1533 Z1 blkd by diff). Another way of blocking the zone is to
set a binary input (No. 3610 „>BLOCK Z1-Trip").
Controlled zone Z1B
The overreaching zone Z1B is a controlled zone. The normal zones Z1 to Z6 are not influenced by Z1B. There
is no zone switching, but rather the overreaching zone is activated or deactivated by the corresponding criteria.
In address 1651 Op. mode Z1B = Forward, it can also be switched to Reverse or Non-Directional. If
this stage is not required, it is set to Inactive (address 1651). The setting options are similar to those of zone
Z1: Address 1652 R(Z1B) Ø-Ø, address 1653 X(Z1B), address 1654 RE(Z1B) Ø-E. The delay times for
single-phase and multiple-phase faults can again be set separately: T1B-1phase (address 1655) and T1B-
multi-phase (address 1656). If parameter Op. mode Z1B is set to Forward or Reverse, a non-directional
trip is also possible in case of closure onto a fault if parameter 1532 SOTF zone is set to Z1B undirect.
(see also Section 2.5.1.4).
Zone Z1B is often used in combination with automatic reclosure and/or teleprotection schemes. It can be acti-
vated internally by the teleprotection functions (see also Section 2.7) or the integrated automatic reclosure (if
available, see also Section 2.17), or externally by a binary input. It is generally set to at least 120 % of the line
length. On three-terminal lines („teed feeders"), it must be set to securely reach beyond the longest line section,
SIPROTEC, 7SD5, Manual
C53000-G1176-C169-5, Release date 02.2011
Functions
2.5 Distance Protection
159