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PAGE 20 — DCA-125USJ (50 HZ) — OPERATION AND PARTS MANUAL — REV. #0 (03/11/05)
DCA-125USJ (50 HZ)— GENERAL INFORMATION
DCA-125USJ (50 HZ) Series Familiarization
Generator
The MQ Power Model DCA-125USJ (50 HZ)is a 80 kW
generator
(Figure 5) that is designed as a high quality
portable (requires a trailer for transport) power source for
telecom sites, lighting facilities, power tools, submersible
pumps and other industrial and construction machinery.
Engine Operating Panel
The “Engine Operating Panel” is provided with the following:
z
Tachometer
z
Water Temperature Gauge
z
Oil Pressure Gauge
z
Charging Ammeter Gauge
z
Fuel Level Gauge
z
Pre-heat Lamp
z
Panel Light/Panel Light Switch
z
Auto ON/OFF Engine Controller (MPEC)
z
Fuel Leak Detected Alarm Lamp
Generator Control Panel
The “Generator Control Panel” is provided with the following:
z
Frequency Meter (Hz)
z
AC Ammeter (Amps)
z
AC Voltmeter (Volts)
z
Ammeter Change-Over Switch
z
Voltmeter Change-Over Switch
z
Voltage Regulator
z
3-Pole, 300 amp Main Circuit Breaker
Control Box
The “Control Box”, located behind the
Generator Control
Panel
, is provided with the following:
z
Automatic Voltage Regulator
z
Current Transformer
z
Over-Current Relay
z
Voltage Rectifer
z
Starter Relay
z
Engine Controller (Computer Controlled)
z
Voltage Selector Switch
Output Terminal Panel
The “Output Terminal Panel” is provided with the following:
z
Three 100/200V output receptacles (CS-6369), 50A
z
Three auxilliary circuit breakers, 50A
z
Two 100V output receptacles (GFCI), 20A
z
Two GFCI circuit breakers, 20A
z
Five output terminal lugs (3Ø power)
z
Battery Charger (Optional)
z
Water Heater (Optional)
Open Delta Excitation System
The DCA-125USJ (50 HZ)generator is equipped with the state
of the art "
Open-Delta
" excitation system. The open delta
system consist of an electrically independent winding wound
among stationary windings of the AC output section.
There are four connections of the open delta A, B, C and D.
During steady state loads, the power from the voltage regulator
is supplied from the parallel connections of A to B, A to D,
and C to D. These three phases of the voltage input to the
voltage regulator are then rectified and are the excitation
current for the exciter section.
When a heavy load, such as a motor starting or a short
circuit occurs, the automatic voltage regulator (AVR)
switches the configuration of the open delta to the series
connection of B to C. This has the effect of adding the voltages
of each phase to provide higher excitation to the exciter
section and thus better voltage response during the
application of heavy loads.
The connections of the AVR to the AC output windings are
for sensing only. No power is required from these windings.
The open-delta design provides virtually unlimited excitation
current, offering maximum motor starting capabilities. The
excitation does not have a "
fixed ceiling
" and responds
according the demands of the required load.
Engine
The DCA-125USJ (50 HZ)is powered by a 4 cycle, water
cooled, direct injection, turbocharged JOHN DEERE
Model
6068TF275 Diesel
Engine
. This engine is designed to meet
every performance requirement for the generator. Reference
Table 1 for engine specifications.
In keeping with MQ Power's policy of constantly improving
its products, the specifications quoted herein are subject to
change without prior notice.
Electric Governor System
The electric governor system controls the RPMs of the
engine. When the engine demand increases or decreases,
the governor system regulates the frequency variation to
±.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 amperage so that the voltage drop
between the generator and point of use (load) is held to a
minimum. Use the cable selection chart (Table 5) as a guide
for selecting proper extension cable size.