Winco DGC-500 - Manual (Page 22)

DGC-500 Functional Description 3-2
Circuits relating to the microprocessor inputs are described in the following paragraphs.
Zero Crossing Detection
The zero crossing of A-phase to B-phase line voltage is detected and used to calculate the generator
frequency.
Analog-to-Digital Converter
Scaled and conditioned signals representing the sensing voltage, sensing current, coolant temperature, fuel
level, oil pressure, and battery voltage are digitized by the microprocessor’s 10-bit analog-to-digital converter.
The digitized information is stored in random access memory (RAM) and used by the microprocessor for all
metering and protection functions.
Voltage Sensing Inputs
Generator voltages applied to the voltage sensing inputs are scaled to levels suitable for use by the internal
circuitry. Voltage sensing configuration is menu-selectable.
The voltage sensing inputs accept a maximum voltage of 576 Vrms, line-to-line. Sensing voltage is applied
to terminals P23 (A-phase), P26 (B-phase), P29 (C-phase), and P30 (Neutral).
Current Sensing Inputs
Generator currents are sensed and scaled to values suitable for use by the internal circuitry. Isolation is
provided by internal current transformers (CTs).
DGC-500–X1 units accept a maximum current value of 1 Aac. DGC-500–X5 units accept a maximum current
value of 5 Aac. Sensing current is applied to terminals P10 and P11 (A-phase), P12 and P14 (B-phase), and
P15 and P17 (C-phase).
Transducer Inputs
Programmable transducer inputs of the give the DGC-500 user the flexibility to select the transducer to be
used in an application. Information about programming the transducer inputs is provided in Section 6,
BESTCOMS Software.
Oil Pressure
A current of less than 30 milliamperes is provided to the oil pressure transducer. The developed voltage is
measured and scaled for use by the internal circuitry. Oil pressure transducers that are compatible with the
DGC-500 include Isspro model R8919, Stewart-Warner models 279BF, 279C, 411K, and 411M, and VDO
models 360025 and 360811. Other senders may be used. BESTCOMS software allows for the programming
of sender characteristics. See Section 4, BESTCOMS Software for more information.
Oil pressure transducer connections are provided at terminals P13 and P19 (sender common).
Coolant Temperature
A current of less than 1.2 milliamperes is provided to the coolant temperature transducer. The developed
voltage is measured and scaled for use by the internal circuitry. Coolant temperature transducers that are
compatible with the DGC-500 include Isspro model R8959 and Stewart-Warner 334-P. Other senders may
be used. BESTCOMS software allows for the programming of sender characteristics. See Section 4,
BESTCOMS Software for more information.
Coolant temperature transducer connections are provided at terminals P18 and P19 (sender common).
Fuel Level
A current of less than 5 milliamperes is provided to the fuel level transducer. The developed voltage is
measured and scaled for use by the internal circuitry. An open circuit or short circuit across the fuel level
transducer terminals will cause the DGC-500 to indicate a failed fuel level transducer. Fuel level transducers
that are compatible with the DGC-500 include Isspro model R8925. Other senders may be used. BESTCOMS