ABB RELION REX640 Technical Manual page 818

Section 4
Protection functions
812
E U I I jX
( ) (
= + − ⋅
AB A B leak
GUID-88D7F9BF-69A7-4956-A1EB-E66BE1FBD681 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
49 98
Excitation level M =
11000
50
GUID-5D8718BF-01C9-4EAF-88DE-FA551BE61645 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
49 98
Excitation level M =
11000
50
GUID-B2DDA43B-BCDA-4ED7-9147-AFC25628C502 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 = 1000 s, Minimum operate time =
1 s and Cooling time = 200 s.
)
.
1 1359 .
=
1 00 .
⋅
.
1 0818 .
=
1 05 .
⋅
1MRS759142 C
(Equation 206)
(Equation 207)
(Equation 208)
REX640
Technical Manual