Siemens Siprotec 7UM611, Руководство пользователя

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2 Functions
82
7UM61 Manual
C53000-G1176-C127-3
Setting example:
Multiplied by a safety factor of about 1.05, the setting value 1/xd CHAR. 1 results
under address 3002 .
For
α
1, the angle of the underexcitation limiting of the voltage regulator is selected or
the inclination angle of the machine stability characteristic is used. The setting value
ANGLE 1 is typically situated between 60
°
and 80
°
.
In most cases, the machine manufacturer prescribes a minimum excitation value for
small active powers. For this purpose, characteristic 1 is cut from characteristic 2 for
low active-power load. Consequently,
1/xd CHAR. 2 is set to about 0.9· ( 1/xd
CHAR. 1 ), the ANGLE 2 to 90
°
. The kinked tripping limit according to figure 2-22
(CHAR. 1, CHAR. 2) results in this way, if the corresponding time delays T CHAR. 1
and T CHAR. 2 of both characteristics are set equally.
Characteristic 3 serves to adapt the protection to the dynamic machine stability limits.
If there are no precise indications, the user must select a value
1/xd CHAR. 3 , ap-
proximately between the synchronous direct reactance xd and the transient reactance
x
d
'. However, it should be greater than 1.
A value between 80
°
and 110
°
is usually selected for the corresponding ANGLE 3 ,
which ensures that only a dynamic instability can lead to a pickup with characteristic
3. The associated time delay is set at address
3010 T CHAR 3 to the value suggested
in Table 2-4.
Figure 2-24 Admittance diagram of a turbogenerator
Machine U
N, Mach
= 6.3 kV
I
N Machine
= SN/
√
3 U
N
= 5270 kVA/
√
3 · 6.3 kV = 483 A
X
d mach
= 2.47
(read from machine manufacturer's specifications in
Figure 2-23)
Current Trans-
former I
N CT prim
= 500 A
Voltage trans-
former U
N VT. prim
= 6.3 kV
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