Siemens SIPROTEC 7UM62, Manual

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90–%–Stator Earth Fault Protection (ANSI 59N, 64G, 67G)
183
7UM62 Manual
C53000-G1176-C149-3
With full neutral displacement voltage, the load resistor supplies:
Referred to the 6.3 kV side, this results in:
The secondary current of the toroidal transformer supplies to the input of the device:
For a protected zone of 90 %, the protection should already operate at 1/10 of the full
displacement voltage, whereby only 1/10 of the earth fault current is generated
In this example
3I0>
is set to 11 mA. For the displacement voltage setting, 1/10 of the
full displacement voltage is used (because of the 90% protected zone). Considering a
voltage divider of 500 V/100 V, this results in:
Setting value
U0>
= 10 V
The time delay must lie below the 50 A capability time of the loading resistor, i.e. below
20 s. The overload capability of the earthing transformer must also be considered if it
lies below that of the loading resistor.
2.26.2.1 Settings of the 90% Stator Earth Fault Protection
Voltage divider 500 V / 100 V
Toroidal c.t. 60 A/1 A
Protected zone 90 %
500 V
10
Ω
---------------
50 A =
I
EE prim
50 A
500 3
⁄
6 300 V 3
( ) ⁄
----------------------------------- 3
⋅ ⋅
6.87 A
= =
I
EE sec
I
EE prim
60 A 1 A
⁄
-------------------------
6.87 A
60
----------------- 115 mA
= = =
Setting 3I0>
115 mA
10
--------------------
11.5 mA = =
Addr. Setting Title Setting Options Default Setting Comments
5001 S/E/F PROT. OFF
ON
Block relay for trip com-
mands OFF Stator Earth Fault Protection
5002 U0> 2.0..125.0 V 10.0 V U0> Pickup
5003 3I0> 2..1000 mA 5 mA 3I0> Pickup
5004 DIR. ANGLE 0..360
°
15
°
Angle for Direction Determina-
tion
5005 T S/E/F 0.00..60.00 sec;
∞
0.30 sec T S/E/F Time Delay