ABB 615 Series ANSI, Техническое руководство, Страница: 265 / 713

Section 4
1MAC050144-MB C
Protection functions
258 615 series ANSI
Technical Manual
Equation 11
The internal induced voltage (E) of the machine is calculated as per Equation 12
Equation 12
E = 11500

0°+ (5600

-63.57°- 5600

176.42°) x (0.170378

90°) = 12490 V.
The excitation level M of the machine is calculated as below:
Excitation level
Example 2
The situation and the data are equal to the example 1. In this case, manufacturer of the
machine allows the continuous operation 105 % of the nominal voltage at the rated load
and this value to be used as the base for overexcitation.
The setting Volt Max continuous is equal to 105%, then the excitation level M of the
machine is calculated as below:
Excitation level
In the definite time operation, if the calculated excitation level M is greater than the setting
Pickup value , PICKUP output is activated. If the excitation level M stays above the set
value for the time equal to set Trip delay time , TRIP output is activated. The definite time
operation is as shown in Figure 123.
Usually the V/f characteristics are specified so that the ratio is 1.00 at the
nominal voltage and the nominal frequency, therefore the value 100% for
setting Volt Max continuous is recommended.
   
Ohms
I
V
X X
n
n
leakPU leak
170378 . 0
3 7455
11000
2 . 0
3








 







 

) ( ) (
leak B A AB
jX I I V E
   
1358 . 1
00 . 1
60
11000
98 . 59
12490



M
0817 . 1
05 . 1
60
11000
98 . 59
12490



M