ABB RELION REX640 Technical Manual page 371

1MRS759142 F
Voltage control mode
In the Voltage control mode, the Effective start value is calculated based on the
magnitude of input voltages U_AB, U_BC and U_CA. The voltage dependency is
phase sensitive, which means that the magnitude of one input voltage controls the
start value of only the corresponding phase, that is, the magnitude of voltage inputs
U_AB, U_BC and U_CA independently control the current start values of phases A, B
and C.
Two voltage control characteristics, voltage step and voltage slope, can be achieved
with the
The voltage step characteristic is achieved when the
equal to the
on the equations.
Voltage level
U <
U ≥
In this example, U represents the measured input voltage. This voltage step
characteristic is graphically represented in
Figure 222: Effective start value for voltage step characteristic
The voltage slope characteristic is achieved by assigning different values to
high limit and Voltage low limit . The effective start value calculation is based on the
equations.
Voltage level
U <
U ≥
REX640
Technical Manual
Voltage high limit and Voltage low limit settings.
Voltage low limit setting. The effective start value is calculated based
Voltage high limit
Voltage high limit
Voltage low limit
Voltage high limit
Protection functions
Voltage high limit setting is
Effective start value (I> effective)
Start value low
Start value
Figure 222
.
Effective start value (I> effective)
Start value low
Start value
Voltage
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