Voltage Memory; Timers; Distance Function Zone Timers; Additional Timers - Siemens 7SG164 Ohmega 400 Series Manual

7SG164 Ohmega 400 Series Performance Specification

2.8 Voltage Memory

Under fault conditions the relay adds a replica of the positive sequence voltage to the polarising voltage of each
comparator.
Voltage memory is applied for a maximum of 200ms, after which time the zone 1 and, where fitted, zone 4
comparators will be either inhibited from operating or have their operation latched until the fault is cleared.

2.9 Timers

2.9.1 Distance Function Zone Timers

Zone Timers (Z1T through Z4T)
0 to 10 s in steps of 10ms

2.9.2 Additional Timers

Timing functions for scheme operation and other protection functions are available. These are model specific and
the relay setting section must be consulted for the individual timing range and step setting.

2.10 Measuring Elements

2.11 Zone 1 and Zone 2 elements

Both zone 1 and zone 2 have six measuring elements each. Three are for phase fault and three are for earth fault.
Each element is independent giving the relay full scheme capabilities. The characteristic shapes available are
circular polarised MHO for phase and earth fault and an option of quadrilateral characteristic for earth fault.

2.12 Zone 3 elements

Zone three has three phase fault phase fault elements and three earth fault elements The characteristic shapes
available for both phase and earth fault are:-
Circular polarised MHO forward
Circular polarised MHO reverse
Circular offset MHO
Phase fault characteristics have the additional feature to allow for load encroachment and can be shaped.
An option of quadrilateral characteristic for earth fault is also available.

2.13 Zone 4 elements

This provides a reverse polarised MHO characteristic or E/F quadrilateral zone and is normally used in schemes
which require reverse fault coverage or blocking schemes.
3

Additional Features

3.1 High Set Overcurrent

A High Set transient free overcurrent element is available this can be selectable to Instantaneous or Definite Time
Lag (DTL). It has the following range of settings:-
0.1 – 6.0I in steps of 0.1
n
6.25 – 35I in steps of 0.25
n
0 – 1.0 s in steps of 0.001 s

3.2 Voltage Transformer Supervision (VTS)

Modes of operation:-
Alarm only
Alarm & inhibit
Inhibit can be selected to either block operation of phase & earth fault elements or to only block operation of earth
fault elements during loss of voltage conditions.
VTS Ires level 0.05 – 2.0 I in steps of 0.1I
n n
VTS Vres level 1 – 100V in steps of 1V
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