Instantaneous Elements - Siemens 7SG11 Manual

P/F Charact Inhib
Ia
* Dir'n A Fwd
Ib
* Dir'n B Fwd
Ic
*
Dir'n C Fwd
Figure 2.3-1
The earth-fault pole similarly has its own delayed overcurrent element with its own starter setting and selectable
IDMT/DTL characteristic.
E/F Charact Inhib
Ie
*
Dir'n E/F Fwd
Figure 2.3-2
2.3.2

Instantaneous elements

There are three separate instantaneous elements per pole: Lowset, Highset 1 and Highset 2. The setting range of
each element allows it to be set and used either as a lowset or highset protection, or for overcurrent monitoring.
For each element common settings are used by each of the three phase fault poles of the relay, each element
has an 'OFF' setting. Each element has a shaped instantaneous characteristic plus follower time delay which can
be used to provide time grading margins, sequence co-ordination grading, or for scheme logic. The instantaneous
elements have transient free, low overreach, operation under conditions of high values of system X/R.
Figure 2.3-2 and the following text describe the operation of the Lowset element, Highset 1 and Highset 2. Each
of these elements is identical in operation.
Each instantaneous element has its own directional control setting Protection:P/F Lowset Dir Control. A current level
setting Protection:P/F Lowset Setting sets the pickup level, which can be followed by a time delay, Protection:P/F Lowset
Delay, the element output is mapped O/P Relay Config.:P/F Lowset.
©2013 Siemens Protection Devices Limited
*
P/F Charact. Dir Control
P/F Charact. Setting
P/F Charact.
P/F Charact. Time Mult
P/F Charact. Delay
Relay Reset Delay
c
Phase A starter
start Event
Phase A delayed trip
c trip Event
Phase B starter
start Event
Phase B delayed trip
c trip Event
Phase C starter
start Event
Phase C delayed trip
c
trip Event
Functional Diagram – Characteristic Phase-fault Overcurrent Element
*
E/F Charact. Dir Control
E/F Charact. Setting
E/F Charact.
E/F Charact. Time Mult
E/F Charact. Delay
Relay Reset Delay
c
Earth starter
start Event
Earth delayed trip
c
trip Event
Functional Diagram – Characteristic Earth-fault Overcurrent Element
7SG11 Argus Technical Reference
This diagram shows the logic for overcurrent
*
elements in the forward direction; reverse is
similar. On relays with no directional elements
these inputs and settings are omitted.
1
P/F Starter
1
P/F Charact.
P300008 Protection Functions / Time Delayed P/F
This diagram shows the logic for overcurrent
*
elements in the forward direction; reverse is
similar. On relays with no directional elements
these inputs and settings are omitted.
E/F Starter
E/F Charact.
P300008 Protection Functions / Time Delayed E/F
P20007 Page 27 of 71