Basler Electric DGC-2020 - Manual (Page 76)

Circuits relating to the microprocessor inputs are described in the following paragraphs.
Zero Crossing Detection
The zero crossing of A-phase to B-phase or A-phase to C-phase (user-selectable) line voltage is detected
and used to calculate the generator frequency. The zero crossing of A-phase to B-phase bus voltage is
used to calculate the bus 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 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.
Watchdog Timer
The watchdog timer monitors the firmware executed by the microprocessor. If the firmware ceases normal
operation, the watchdog timer will reset the microprocessor. After reset, the microprocessor will resume
normal operation if the condition that caused the watchdog reset is no longer present. If the condition is
still present, the unit will reset repeatedly until it can resume normal operation.
Generator Voltage Sensing Inputs
Voltages applied to the generator voltage sensing inputs are scaled to levels suitable for use by the
internal circuitry. Generator voltage sensing configuration is menu-selectable.
The generator voltage sensing inputs accept a maximum voltage of 576 Vrms, line-to-line. Sensing
voltage is applied to terminals 41 (A-phase), 39 (B-phase), 37 (C-phase), and 35 (neutral).
Bus Voltage Sensing Inputs
Voltage applied to the bus voltage sensing input is scaled to a level suitable for use by the internal
circuitry.
The bus voltage sensing input accepts a maximum voltage of 576 Vrms. For hardware version 3, sensing
voltage is applied to terminals 76 (A-phase), 78 (B-phase), and 80 (C-phase). For hardware versions 1
and 2, sensing voltage is applied to terminals 45 (A-phase) and 43 (B-phase).
In version 3 hardware, terminal 45 is internally tied to 76 and terminal 43 is internally tied to 78. This
accommodates the use of connectors wired for legacy DGC-2020 versions.
Current Sensing Inputs
Generator currents are sensed and scaled to values suitable for use by the internal circuitry.
DGC-2020 controllers with 1 ampere current sensing (style number 1xxxxxxxx) accept a maximum
current value of 1 Aac. DGC-2020 controllers with 5 ampere current sensing (style number 5xxxxxxxx)
accept a maximum current value of 5 Aac. Sensing current is applied to terminals 68 (IA–) and 69 (IA+),
71 (IB–) and 72 (IB+), and 74 (IC–) and 75 (IC+).
Analog Engine Sender Inputs
Programmable analog engine sender inputs give the DGC-2020 user the flexibility to select the engine
sender to be used in an application. Information about programming the sender inputs is provided in
Section 4, BESTCOMSPlus
® Software.
Oil Pressure
A current is provided to the oil pressure sender. The developed voltage is measured and scaled for use
by the internal circuitry. An open circuit or short circuit across the oil pressure sender terminals will cause
the DGC-2020 to indicate a failed sender. Oil pressure senders that are compatible with the DGC-2020
include Datcon model 02505-00, Isspro model R8919, and Stewart-Warner models 411K and 411M.
Other senders may also be used. BESTCOMSPlus
® software allows for the programming of sender
characteristics. See Section 4, BESTCOMSPlus
® Software, for more information.
Oil pressure sender connections are made at terminals 8 and 11 (sender common).
Coolant Temperature
A current is provided to the coolant temperature sender. The developed voltage is measured and scaled
for use by the internal circuitry. An open circuit or short circuit across the coolant temperature sender
3-2 DGC-2020 Functional Description 9400200990 Rev X