ABB 615 Series - Page 659

The pu leakage reactance X
leakPU
is converted to ohms.
X X
V
I
leak leakPU
n
n
Ω
= ⋅
⋅
( )








= ⋅
⋅
( )








=
3
0 2
11000
7455 3
. 00 170378. ohms
GUID-7A3ABF69-50C4-4F5D-A466-61CAB055B604 V1 EN (Equation 124)
The internal induced voltage E of the machine is calculated.
E V I I jX
AB A B leak
= + − ⋅( ) ( )
GUID-DBA66DD4-E087-4624-BDCE-E74167CAB5DE V1 EN (Equation 125)
E = 11500∠0°+ (5600∠-63.57°- 5600∠176.42°) · (0.170378∠90°) = 12490 V
The excitation level M of the machine is calculated.
Excitation level M =
⋅
=
12490
49 98
11000
50
1 00
1 1359
.
.
.
GUID-28DEBF41-9058-4C7B-985F-FA7131DF39A7 V1 EN (Equation 126)
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 V/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.
Excitation level M =
⋅
=
12490
49 98
11000
50
1 05
1 0818
.
.
.
GUID-3422B6EB-4564-4EFD-B60A-50CB18850054 V1 EN (Equation 127)
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: Pickup value = 110%, Voltage Max Cont = 100%,
Time multiplier = 4, Maximum trip time = 1000 s, Minimum trip time = 1 s and Cooling
time = 200 s.
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 653
Technical Manual