ABB RELION 620 Series Technical Manual page 687

1MRS757644 F
620 series
Technical Manual
The internal induced voltage E of the machine is calculated.
E U ( I I ) ( jX
= + − ⋅
AB A B
GUID-7277AB82-6BAD-4849-A4CC-18C6EEEB4AC5 V1 EN
E = 11500∠0°+ (5600∠-63.57°- 5600∠176.42°) · (0.170378∠90°) = 12490 V
The excitation level M of the machine is calculated.
12490
Excitation level M =
11000
GUID-28DEBF41-9058-4C7B-985F-FA7131DF39A7 V1 EN
Example 2
The situation and the data are according to Example 1. In this case, the manufacturer
of the machine allows the continuous operation at 105 percent of the nominal voltage
at the rated load and this value to be used as the base for overexcitation.
Usually, the U/f characteristics are specified so that the ratio is 1.00 at
the nominal voltage and nominal frequency. Therefore, the value 100
percent for the setting Voltage Max Cont is recommended.
If the Voltage Max Cont setting is 105 percent, the excitation level M of the machine
is calculated with the equation.
12490
Excitation level M =
11000
GUID-3422B6EB-4564-4EFD-B60A-50CB18850054 V1 EN
Example 3
In this case, the function operation is according to IDMT. The Operating curve type
setting is selected as "OvExt IDMT Crv2". The corresponding example settings for
the IDMT curve operation are given as: Start value = 110%, Voltage Max Cont =
100%, Time multiplier = 4, Maximum operate time = 1000000 milliseconds and
Minimum operate time = 1000 milliseconds.
)
leak
49 98 .
1 1359 .
=
1 00 .
⋅
50
49 98 .
1 0818 .
=
1 05 .
⋅
50
Section 4
Protection functions
(Equation 138)
(Equation 139)
(Equation 140)
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