Switch On To Fault; Power Swing; Fault Locator; Indication - Siemens 7SG164 Ohmega 400 Series Manual

Output configuration:-
Instantaneous operation/reset
Minimum delayed alarm 100ms
Delayed alarm/reset 0.1 – 60s

3.3 Switch On To Fault

Two arrangements provide instantaneous tripping when switching on to a bolted three-phase fault.
a) D.C. Line check
This arrangement is energised from the circuit breaker closing circuit and allows instantaneous zone 3 coverage
for a period of 400ms after energising the line.
b) A.C. Line check
This arrangement is not dependant on the circuit breaker closing circuit and allows instantaneous zone 3
coverage for a period of 200 ms after the line is energised. After the line is de-energised the line check resets
after the programmed time delay. Line de-energisation is detected by three-phase pole-dead logic, while the line
check measurement uses this in conjunction with phase current detectors.

3.4 Power Swing

The power swing element has a circular or rectangular offset element that consists of two concentric
characteristics. The inner zone impedance is set between the ranges of 0.1 – 250 Ohms and the outer zone has a
setting, which is a multiplier of the inner zone. This is set between 1.05 and 2x in steps of 0.01x.
The blocking detector uses a transition time between the inner and outer boundaries this is adjustable between 0
– 1000 ms in 5 ms steps.
The power swing blocking function will be released during an unsymmetrical fault.
The blocking can be arranged to block any zone.

3.5 Fault Locator

The fault locator is triggered by the fault recorder in the event of a general trip. It uses information from the
waveform record associated with the fault to determine both the fault type and the line impedance between the
relay and the fault location, ignoring any fault resistance. This information is then displayed as part of the relay
fault record. By default, the location is displayed as a percentage of the positive sequence line impedance. This
can be set in the range 0.1 – 250 ohms in magnitude, and uses the relay line angle as set for the distance
protection.
The fault location can be displayed instead as a distance in miles or kilometres by selecting the required display
units, and by setting an appropriate value for the secondary positive sequence impedance per unit length. This
can be set in the range 0.001 to 5.000 ohms.
4

Indication

Indication is provided by 32 red LEDs; these are fully configurable to the user. Adjacent to each column of LEDs
is a removable strip on which the LED function can be printed, allowing comprehensive fault indication. It is
possible to print the indicator strip in languages other than English. The LCD provides further fault indication and
can be used for programming the relay. See section 1 for a detailed explanation for the programming of the relay.
5

Output contacts

As with the indication the output contacts are fully programmable the basic I/O module has 5 output contacts three
of which are change over. Additional modules can be added to provide more contacts. These are added in-
groups of eight.
6

Status inputs

As with the indication and output contacts the status inputs are fully programmable the basic I/O module has 3
status inputs these can be set to high speed for signalling. Additional modules can be added to provide more
inputs. These are added in-groups of eight.
©2011 Siemens Protection Devices Limited
7SG164 Ohmega 400 Series Performance Specification
Chapter 5 Page 5 of 13