Basler Electric DECS-100 - Manual (Page 28)

3-4 DECS-100 Functional Description 9287500991 Rev M
contact inputs, the Accessory input, or through BESTCOMS software. The regulation point may also be
modified by the Droop function or the Underfrequency function under certain conditions.
Manual Mode
In Manual mode, also known as Field Current Regulation (FCR) mode, the DECS-100 maintains dc
excitation current at a set level. The current-level setpoint is adjustable from 0 to 7 Adc in 0.01 Adc
increments by the Raise and Lower contact inputs, the Accessory input, or through BESTCOMS software.
Var Control Mode (Optional)
In Var Control mode, the DECS-100 maintains generator vars (volt-amperes, reactive) at a set level when
paralleling with an infinite bus. The DECS-100 calculates generator vars by using the sensed generator
output voltage and current quantities. It then adjusts the dc excitation current to maintain vars at the
setpoint. Var control is enabled and disabled through BESTCOMS software. When the software is turned
on, var control is enabled or disabled through the Var/Power Factor Control (52J/K) contact input circuit.
The var setpoint is adjustable from 100 percent absorb to 100 percent generate through the Raise and
Lower contact inputs, the Accessory input, or through BESTCOMS software.
Power Factor Control Mode (Optional)
In Power Factor Control mode, the DECS-100 maintains generator power factor at a set level when
paralleling with an infinite bus. The DECS-100 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 BESTCOMS 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, the Accessory input, or through BESTCOMS software.
Reactive Droop Compensation
The DECS-100 provides a reactive droop compensation feature to assist in the sharing of reactive load
during parallel generator operation. When this feature is enabled, the DECS-100 calculates the reactive
portion of the generator load using the sensed generator output voltage and current quantities and then
modifies 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 (1 ampere or 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). Droop is also disabled when operating in var or power factor control modes.
Underfrequency
When generator frequency drops below the selected knee frequency setpoint, the voltage setpoint is
automatically adjusted by the DECS-100 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 lights on the
front panel and in BESTCOMS. Underfrequency control is disabled below 12 hertz. The knee frequency is
adjustable from 40 to 65 hertz in 0.1 hertz increments and the PU V/Hz curve may be set at a slope of 0
to 3 in 0.01 steps through BESTCOMS software. A slope of 0 effectively disables the underfrequency
function. The DECS-100 has a minimum regulation point of approximately 30 percent of the nominal
setpoint.
Protection
The DECS-100 includes three protective functions: generator overvoltage, loss of sensing voltage, and
field overvoltage. Each protective function has a corresponding front panel indicator that lights when the
function is active. An active protective function is also annunciated through BESTCOMS.
CAUTION
The Manual mode excitation level must be evaluated prior to enabling this
feature. If the level of excitation current is inappropriate for the generator, severe
damage to the generator may occur.