ABB RELION REX640 Technical Manual page 372

Protection functions
Voltage low limit ≤ U < Voltage high limit ,
If
I>(effective) = I> - [ ((I> - A) / (C – D)) * (C – U) ]
A
I>
C
D
Here U represents the measured input voltage. The voltage slope characteristic is
graphically represented.
Figure 223: Effective start value or voltage slope characteristic
External input control mode
The External input control mode is used to enable voltage control from an external
application. If
value for all phases is influenced by the status of the binary input ENA_U_MULT.
372
Start value low
set
Start value
set
set Voltage high limit
Voltage low limit
set
To achieve the voltage slope characteristics,
always be set to a value greater than
Voltage high limit is lower than Voltage low limit , the voltage step
If
characteristic is active with
The value of the setting
Start value low . Otherwise, Start value low is used as the effective
setting
start value.
Control mode is set to the "Input Control" mode, the effective start
Voltage high limit must
Voltage low limit .
Voltage low limit being the cutoff value.
Start value should always be greater than the
1MRS759142 F
(Equation 28)
REX640
Technical Manual