ABB RELION REX640, Техническое руководство, Страница: 1416 / 1960

Active power (P)
Rack
position
Rack Pos No load
dR/dP = Rack Pos Gain
dR
dP
Figure 801: Rack position vs. Active power output of the generator
Excitation current monitoring
The excitation current,
I_EXCITATION
, produced by the AVR is compared to the
reactive power output,
Q
, of the generator. A linear relationship is assumed between
I_EXCITATION
and
Q
. The
I_EXCITATION
input is a 0-20mA signal obtained
through an
RTD
input and is in primary Amperes.
The droop characteristics can be parameterized using the settings
Ext current no
load and Ext current gain. If the performance of the generator deviates from this
relationship, the module activates the output
I_EXCT_FLT
. The module can be
disabled using the setting Disable Ext Cur Mon.
For both the Fuel rack position monitoring and the Excitation current
monitoring modules, an internal delay of 100ms is assumed before
activation of
FUEL_RCK_FLT
and
I_EXCT_FLT
outputs. This delay is to
enable the generator mechanics to respond to the changes in fuel rack
position and excitation current.
7.5.5.3 Control logic
Once activated by either the Fuel fault detection module or by the Excitation fault
detection module, the Control logic module activates the
FLT_DETECTED
output.
This output serves as an indication for the operator or the central PMS to start
standby engines or alter the power sharing between healthy diesel generators.
If the network frequency and voltage deteriorate beyond control, the module
activates the
STOP_ENGINE
(incase of fueling faults) and
DE_EXCITE
(incase of
Condition monitoring functions 1MRS759142 F
1416 REX640
Technical Manual