Marathon DVR 2000E - Reactive Droop Compensation; Underfrequency; Engine Unloading; Protection

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with an innite bus. The DVR2000E(C) calculates generator power factor using the sensed generator output
voltage and current quantities and then adjusts the dc excitation current to maintain power factor at the setpoint.
Power factor control is enabled or disabled through the front panel switches, Windows® or Palm OS® software.
When the software is turned on, it is enabled or disabled through the Var/Power Factor Control (52J/K) contact
input circuit. The power factor setpoint is adjustable between 0.6 lag and 0.6 lead through the Raise and Lower
contact inputs, front panel switches, or through Windows® or Palm OS® communication software.
Reactive Droop Compensation
The DVR2000E provides a reactive droop compensation feature to assist in the sharing of reactive load during
parallel generator operation. When this feature is enabled, the DVR2000E calculates the reactive portion of the
generator load using the sensed generator output voltage and current quantities and then modies the voltage
regulation setpoint accordingly. A unity power factor generator load results in almost no change in generator
output voltage. A lagging power factor generator load (inductive) results in a reduction of generator output voltage.
A leading power factor generator load (capacitive) results in an increase of generator output voltage. Droop
is adjustable up to 10 percent with rated, nominal B-phase line current (5 amperes applied through terminals
CT1 and CT2) and 0.8 power factor. The droop feature is enabled and disabled through the Parallel Generator
Compensation contact input circuit (terminals 52L and 52M). If the Var/Power Factor option is present, the 52J/K
input must also be closed to disable droop.
Underfrequency
Generator Underfrequency
When generator frequency drops below the selected knee frequency setpoint, the voltage setpoint is automatically
adjusted by the DVR2000E so that generator voltage follows the selected PU (per unit) V/Hz curve. When
operating on the selected PU V/Hz curve, the Underfrequency Active indicator ashes on the front panel and in
MARATHON-DVR2000E-32. The knee frequency is adjustable from 40 to 65 hertz and the PU V/Hz curve may
be set to a slope from 1 to 3 in increments of 0.01 through the Windows® or Palm OS® communication software.
The default is 59 Hz and a slope of 1.
Engine Unloading
The Engine Unloading feature modies the underfrequency curve. This feature becomes active when the generator
frequency decreases a programmable amount (Unloading Activation – Frequency) below the knee frequency
setpoint, and when the speed change rate is greater than the Unloading Activation - Rate. The amount of droop
while Engine Unloading is active is adjusted by the Unloading Droop - Percentage (%) setting. The amount of time
Engine Unloading is active is set by Unloading Droop - Time (sec.).
Engine unloading adjustments are made through the Windows and Palm OS communication software.
Unloading Activation – Frequency (Hz) is entered as a value below the underfrequency corner where the engine
unloading feature may be activated. A frequency value of 0.9 to 9.0 hertz can be entered in 0.1 hertz increments.
The default value is 0.9 hertz.
Unloading Activation – Rate (Hz/25 msec) of 0 to 25.5 hertz per 25 milliseconds can be entered in 0.1 hertz per
25 millisecond increments. The engine unloading feature is activated when the frequency rate of change exceeds
the setting of this eld. The default value is 0.1.
Unloading Droop – Percentage (%) eld denes the percent drop in generator output voltage for each 1.5 percent
decrease in generator frequency when operating in the Engine Unloading mode. The Unloading Droop Percentage
is adjustable from 1 to 20 percent in 1 percent steps. The default value is 10 percent.
Unloading Droop – Time (sec) value denes the length of time that the Engine Unloading mode may be active
before control is passed to the normal Underfrequency mode of operation. Droop time is adjustable from 1 to 5
seconds in 1 second increments. The default value is 1 second.
Protection
The DVR2000E has the six protective functions listed below:
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Section 3 Index
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Main Index
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Section 3 Index