sepam 20 user manual - Schneider Electric

MT10252
Network diagnosis
functions
tripping order
T0
PCRED301005EN - 06/2008
I
TRIP 1
30 ms
t
Tripping current
Negative sequence / unbalance
Tripping current
Operation
This function gives the RMS value of currents at the prospective time of the last trip:
b TRIP1: phase 1 current
b TRIP2: phase 2 current
b TRIP3: phase 3 current
b TRIPI0: residual current.
It is based on measurement of the fundamental component.
This measurement is defined as the maximum RMS value measured during a 30 ms
interval after the activation of the tripping contact on output O1.
The tripping currents are saved in the event of a power failure.
Readout
The measurements may be accessed via:
b the display of a Sepam with advanced UMI by pressing the key
b the display of a PC with the SFT2841 software
b the communication link.
Characteristics
Measurement range phase current 0.1 to 40 In (1)
Residual current 0.1 to 20 In0 (1)
Unit A or kA
Accuracy ±5 % ±1 digit
Display format 3 significant digits
Resolution 0.1 A or 1 digit
(1) In/In0 rated current set in the general settings.
Negative sequence / unbalance
Operation
This function gives the negative sequence component: T = Ii/Ib
The negative sequence current is determined based on the phase currents:
b 3 phases
1
Ii -- I1 a
3
2 = × ( + I2 + aI3)
with a
j
e
b 2 phases
2π
=
------
3
Ii
1
------ I1 a
3
2 = × – I3
with a
j
e
These 2 formulas are equivalent when there is no earth fault.
2π
=
------
3
Readout
The measurements may be accessed via:
b the display of a Sepam with advanced UMI by pressing the key
b the display of a PC with the SFT2841 software
b the communication link.
Characteristics
Measurement range 10 to 500
Unit % Ib
Accuracy ±2 %
Display format 3 significant digits
Resolution 1 %
Refresh interval 1 second (typical)
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