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GE P743 User Manual

GE P743
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Commissioning
P74x/EN CM/Na7
MiCOM P741, P742, P743
(CM) 10-29
CM
I
bias
is fixed to a lowest value of ID>2/k2 and IDCZ>2/kCZ, the Az and Acz points will thus be
ID>2 and IDCZ>2. So I
bias
= I
1
+ I
2
= fixed value (Points A)
To test the slopes:
I
bias
is fixed to a value greater than ID>2/k2 and IDCZ>2/kCZ the Bz and Bcz points will thus
be I
bias
x k2 and I
bias
x kCZ. So I
bias
= I
1
+ I
2
= fixed value (Points B)
When we reach the point Xcz the Central Unit LED 8 and relay 8 will operate and when we
reach the point Xz the differential element will operate.
To calculate the slope k, k = (I
1
– I
2
) / (I
1
+ I
2
)
The differential current will increase twice the value I.
Note 1: I
D
>1 alarm timer will be set to 100s during the test.
Note 2: Whenever possible, inject 2 × I
D
>2. Alternatively, the minimum current
must be higher than 1.7 × I
D
>2 at 60Hz and I.42 × I
D
>2 at 50Hz in
order to ensure a 15ms tripping time
6.3.1.2
Slopes and thresholds
If a LED has been assigned in central or/and peripheral units to display the trip information,
these may be used to indicate correct operation. If not, monitor option will need to be used
see the next paragraph.
On P741 go Central Unit GROUP1-->BUSBAR PROTECT and set I
D
>1 Alarm timer to 100s
On P742/3 go to COMMISSION TESTS column in the menu, scroll down and change cells
[Monitor Bit 1] to [BUSBAR_TRIPPING]. Doing so, cell [Test Port Status] will appropriately
set or reset the bits that now represent BUSBAR_TRIPPING (with the rightmost bit
representing Busbar Trip. From now on you should monitor the indication of [Test Port
Status]. Make a note of which elements need to be re-enabled or re-set after testing.
Test of I
D
>2:
I
D
>1 Alarm Timer should be set to 100s during testing.
Inject a I
2
current smaller than I
D
>2 and slowly increase I
2
until tripping.
Test of the operating time of the differential element:
Inject a I
2
current greater than twice I
D
>2 threshold and measure the operating time of the
differential element.
Test of I
D
>1:
I
D
>1 Alarm Timer should be set to 100ms.
Inject a I
2
current smaller than I
D
>1 and slowly increase I
2
until circuit fault appears (LED
Alarm of LED circuitry fault).
Test of I
D
>1 Alarm Timer:
I
D
>1 Alarm Timer should be set to 5s.
Inject a I2 current greater than twice the I
D
>1 threshold and check that the Circuitry Fault
Alarm is coming in 5s.
Note: Same tests can be applied for the Differential Sensitive Earth Fault Protection.
Note: the Sensitive Differential Earth Fault (SDEF) is 20ms delayed and controlled by a
settable threshold I
bias
ph> to unblock/block the sensitive element depending of the restrain
phase currents.
IMPORTANT NOTE: Check that if the SDEF is enabled, all the CTs are of the same
standard.

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GE P743 Specifications

General IconGeneral
BrandGE
ModelP743
CategoryRelays
LanguageEnglish

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