
PAGE 20 — DCA-25USI — OPERATION AND PARTS MANUAL (STD) — REV. #0 (05/10/04)
DCA-25USI — GENERAL INFORMATION
DCA-25USI FAMILIARIZATION
Generator
The MQ Power Model DCA-25USI (Figure 4) is a 20 kW
generator
thatisdesignedasahighqualityportable(requires
atrailerfortransport)powersourcefortelecomsites,lighting
facilities, power tools, submersible pumps and other
industrial and construction machinery.
Engine Operating Panel
The“Engine Operating Panel”is providedwiththefollowing:
z
Tachometer
z
WaterTemperature Gauge/ AlarmLamp
z
Oil Pressure Gauge/ Alarm Lamp
z
ChargingAmmeterGauge
z
Pre-HeatLamp
z
Panel Light
z
Panel Light Switch
z
Ignition/Preheat Switch
z
FuelGauge
z
Fuel FilterWater Level Alarm Lamp
Generator Control Panel
The“GeneratorControlPanel”is providedwith the following:
z
Output Voltage Adjustment Knob
z
FrequencyMeter (Hz)
z
AC Ammeter (Amps)
z
AC Voltmeter (Volts)
z
AmmeterChange-Over Switch
z
Voltmeter Change-Over Switch
z
Voltage Regulator
z
3-Pole, 60 amp Main Circuit Breaker
Output Terminal Panel
The “OutputTerminal Panel” is provided with the following:
z
Three120/240Voutputreceptacles(CS-6369),50amps
z
Three auxilliary circuit breakers @50 amps
z
Two 125 VAC output receptacles (GFCI), 20 amps
z
Two GFCI circuit breakers @ 20amps
z
Five output terminal lugs (3Ø power)
Control Box
The “Control Box” is provided with the following:
z
AutomaticVoltage Regulator
z
CurrentTransformer
z
Emergency Relay
z
Over-CurrentRelay
OpenDelta Excitation System
The DCA-25USI generator is equipped with the state of the art
"
Open-Delta
"excitationsystem.Theopendelta systemconsistof
an electrically independent winding wound among stationary
windingsoftheACoutputsection.
TherearefourconnectionsoftheopendeltaA,B,C andD.During
steadystateloads,thepowerfromthevoltageregulatorissupplied
fromtheparallelconnectionsofAtoB,AtoD,andCtoD.Thesethree
phasesofthevoltageinputtothevoltageregulatorarethenrectified
andaretheexcitationcurrentfortheexcitersection.
Whenaheavyload,suchasamotorstartingorashortcircuitoccurs,
theautomaticvoltageregulator(AVR)switchestheconfigurationof
theopendeltatotheseriesconnectionofBtoC.Thishastheeffect
ofaddingthevoltagesofeachphasetoprovidehigherexcitationto
the exciter section and thus better voltage response during the
applicationofheavyloads.
The connections of the AVR to the AC output windings are for
sensingonly.Nopowerisrequired fromthesewindings.
Theopen-deltadesignprovidesvirtuallyunlimitedexcitationcurrent,
offering maximum motor starting capabilities.The excitation does
nothavea"
fixedceiling
"andrespondsaccordingthedemandsof
therequiredload.
Engine
The DCA-25USI is powered by a 4 cycle, water cooled Isuzu
AA-4LE2
diesel
engine.This engine is designed to meet every
performance requirement for the generator.ReferenceTable 2 for
enginespecifications.
InkeepingwithMultiquip'spolicyofconstantlyimprovingitsproducts,
thespecificationsquotedhereinaresubjecttochangewithoutprior
notice.
ThebasiccontrolsandindicatorsfortheDCA-25USIgeneratorare
addressedonthefollowingpages.
Mechanical Governor System
ThemechanicalgovernorsystemcontroltheRPMoftheengine.
Whentheenginedemandsincreaseordecrease,themechanical
governorsystemregulatesthefrequencyvariationtowithin±.5%.
Theelectronicgovernoroptiondecreasesthefrequencyvariation
towithin±0.25%.
Extension Cables
When electric power is to be provided to various tools or loads at
some distance from the generator, extension cords are normally
used. Cables should be sized to allow for distance in length and
amperagesothatthevoltagedropbetweenthegeneratorandpoint
of use (load) is held to a minimum.Use the cable selection chart
(Table5)as a guide forselecting proper extensioncable size.
Go to Discount-Equipment.com to order your parts