2 Functions
164
7SA522 Manual
C53000-G1176-C155-3
The earth fault protection must be blocked during single-pole automatic reclose dead
time, to avoid pick-up with the false zero sequence values and, if applicable, the neg-
ative sequence values arising during this state (address %/2&.S'HDG7LP).
A setting of <(6 (default setting for devices with single-pole tripping) is required if
single-pole automatic reclosure is to be carried out. Otherwise set 12. Setting param-
eter %/2&.S'HDG7LP to <(6 completely blocks the earth fault protection if
the Open-Pole Detector has recognized a single-pole dead time. If no single-pole trip-
ping is carried out in the protected network, it is absolutely necessary to set this pa-
rameter to 12.
Regardless of how parameter address %/2&.S'HDG7LP is set, the earth fault
protection will always be blocked during the single-pole dead time, if it has issued a
trip command itself. This is necessary because otherwise the picked up earth fault pro-
tection cannot drop out if the fault current was caused by load current.
Trip Address 7ULSSROH() specifies that the earth fault protection trips single
pole, provided that the faulted phase can be determined with certainty. This address
is only valid for devices that have the option to trip single-pole. If you are using single-
pole automatic reclosure, the setting <(6 (default setting) remains valid. Otherwise
set 12.
Definite Time
Stages
First of all, the mode for each stage is set: address 2SPRGH,!!!, address
2SPRGH,!! and address 2SPRGH,!. Each stage can be set
to operate )RUZDUG (usually towards line), 5HYHUVH (usually towards busbar) or
1RQ'LUHFWLRQDO (in both directions). If a single stage is not required, set its mode
to ,QDFWLYH.
The definite time stages ,!!! (address ), ,!! (address ) and ,!
(address ) can be used for a three-stage definite time overcurrent protection.
They can also be combined with the inverse time stage ,S3,&.83 (address ,
see below). The pick up thresholds should in general be selected such that the most
sensitive stage picks up with the smallest expected earth fault current.
The 3I
0
>> and 3I
0
>>> stages are best suited for fast tripping stages (instantaneous),
as these stages use an abridged filter with shorter response time. On the other hand,
the stages 3I
0
> and 3I
0P
are best suited for very sensitive earth fault detection due to
their effective method of suppressing harmonics.
If no inverse time stage but rather a fourth definite time stage is required, the “inverse
time” stage can be implemented as a definite time stage. This must already be taken
regard of during the configuration of the protection functions (refer to Section 2.1.1.2,
address (DUWK)DXOW2& = 'HILQLWH7LPH). For this stage, the address
,S3,&.83 then determines the current pickup threshold and address
$GG7'(/$< the definite time delay.
The values for the time delay settings 7,!!! (address ), 7,!! (address
) and 7,! (address ) are derived from the earth fault grading coordina-
tion diagram of the system.
During the selection of the current and time settings, regard must be taken as to
whether a stage should be direction dependent and whether it uses teleprotection.
Refer also to the margin headings “Determination of Direction” and “Teleprotection
with Earth Fault Protection”.
The set time delays are pure additional delays, which do not include the operating time
(measuring time).
To Next Page
Loading...
Need help?
General
