General Information - MULTIQUIP MQ Power DCA25USIXF Operation And Parts Manual

FAMILIARIZATION
Generator
The MQ Power DCA-25USIXF/DCA-25USI2XF Ultra-Silent
generators (Figure 5) are 56 kW generators that are 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:
 Tachometer
 Water Temperature Gauge/ Alarm Lamp
 Oil Pressure Gauge/ Alarm Lamp
 Charging Ammeter Gauge
 Pre-Heat Lamp
 Panel Light
 Panel Light Switch
 Ignition/Preheat Switch
 Fuel Gauge
 Fuel Filter Water Level Alarm Lamp
 Fuel Leak Detected Alarm Lamp
Generator Control Panel
The "Generator Control Panel" is provided with the following:
 Frequency Meter (Hz)
 AC Ammeter (Amps)
 AC Voltmeter (Volts)
 Ammeter Change-Over Switch
 Voltmeter Change-Over Switch
 Voltage Regulator
 3-Pole, 60 amp Main Circuit Breaker
Output Terminal Panel
The "Output Terminal Panel" is provided with the following:
 Two 250 VAC output receptacles (CS-6369), 50 amps
 Two auxilliary circuit breakers, 250V @50 amps
 Two 125 VAC output receptacles, (GFCI), 20 amps
 Two GFCI circuit breakers, 125V@ 20amps
 Five output terminal lugs (3Ø power)
Control Box
The "Control Box" is provided with the following:
 Automatic Voltage Regulator
 Current Transformer
 Emergency Relay
DCA25USIXF/DCA25USI2XF — OPERATION AND PARTS MANUAL — REV. #2 (07/26/11) — PAGE 17

GENERAL INFORMATION

Open Delta Excitation System
This 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 ot 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
These generator's are powered by two different types of diesel
engines depending on the model of the generator. Both engines are
4 cycle, water cooled, direct injection types. The DCA25USIXF
incorporates an ISUZU AA-4LE2 diesel engine, while the
DCA25USI2XF incorporates an ISUZU BB-4LE2 diesel engine.
These engines are designed to meet every performance requirement
for the generator. Reference Table 2 for engine specifications.
In keeping with Multiquip's policy of constantly improving its products,
the specifications quoted herein are subject to change without prior
notice.
The basic controls and indicators for the generator are addressed
on the following pages.
Mechanical Governor System
The mechanical governor system control the RPM of the engine.
When the engine demands increase or decrease, the mechanical
governor system regulates the frequency variation to ±.5%. The
electronic governor option increases frequency variation to ±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
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 6 ) as a guide for selecting proper extension cable size.
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