DECS-100 Functional Description
3-3
Var/Power Factor Control (52J/K) Option
Closing a contact across terminals 52J and 52K disables var/power factor control. An open contact enables
the DECS-100 to control the generator reactive power in either the var or the power factor mode. The contact
has no effect when this function is not enabled in the software. For more information, refer to the Parallel
Generator Compensation (52L/M) contact input.
Parallel Generator Compensation (52L/M)
Closing a contact across terminals 52L and 52M disables parallel operation. An open contact enables parallel
operation and the DECS-100 operates in reactive droop compensation mode.
If the Var/Power Factor Control option is present and is enabled in the software, the 52J/K input has priority.
Therefore, if the 52J/K and the 52L/M inputs are both open, the system operates in var/power factor mode.
Voltage Matching Control Option
If the Voltage Matching option is enabled in the software, closing a contact across terminals VM and VMC
causes the DECS-100 to operate in the voltage matching mode. An open contact disables voltage matching.
RS-232 Communication Port
The communication port provides the interface for user programming (setup) of the DECS-100. Connection
is made to the female RS-232 (DB-9) connector with a user-supplied, standard 9-pin cable. The
communication port is optically isolated and is powered from a transformer-isolated supply.
Microprocessor
The microprocessor is the heart of the DECS-100 and performs measurement, computation, control, and
communication functions by the use of its embedded programming and the nonvolatile settings stored in its
memory.
Power Input Stage
Input power applied to terminals 3, 4, and 5 is rectified and filtered before being applied to the power amplifier
and the power supply. Input power may be single-phase or three-phase in the range of 88 to 250 Vac at a
frequency of 50 to 400 hertz.
The input power source should be properly fused for the application.
Power Supply
The internal switch-mode power supply receives power from the power input stage and supplies power at
the required dc voltage levels to the internal circuitry of the DECS-100.
Power Amplifier Stage
The power amplifier receives power from the power input stage and supplies a controlled amount of power
to the exciter field via terminals F+ and F–. The amount of power supplied to the exciter field is based on
gating pulses received from the microprocessor. The power amplifier uses a solid state power switch to
provide the required power to the exciter field. Power amplifier output to the field is rated up to 63 Vdc at 7
Adc continuous and 135 Vdc at 15 Adc for 10 seconds.
Front Panel Indicators
Seven front panel LED indicators light to indicate various protective functions and operating modes. Section
2,
Human-Machine Interface provides more information about the front panel indicators.
Relay Output
A common alarm output contact is provided through terminals AL1 and AL2. This normally open, form A
contact annunciates alarm or trip conditions. The relay output is non-latching.