Multiquip operation manual DCA-70SSJU Series General Information

DCA-70SSJU SERIES — GENERAL INFORMATION

DCA-70SSJU Series Familiarization

Generator

The MQ Power Model DCA-70SSJU Series is a 26 kW generator (Figure 4) 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:

Tachometer

Water Temperature Gauge

Oil Pressure Gauge

Charging Ammeter Gauge

Engine Throttle Handle (Up to S/N 7302410)

Fuel Level Gauge

Engine Speed Switch (S/N 7302141~)

Cold Starting Button

Panel Light

Panel Light Switch

Ignition/Preheat Switch ( Up to S/N 7302410)

Auto ON/OFF Engine Controller (S/N 7302141~)

Generator Control Panel

The “Generator Control Panel” is provided with the following:

Output Voltage Adjustment Knob

Frequency Meter (Hz)

AC Ammeter (Amps)

AC Voltmeter (Volts)

Ammeter Change-Over Switch

Voltmeter Change-Over Switch

Voltage Regulator

Over-Current Relay

Output Terminal Panel

The “Output Terminal Panel” is provided with the following:

Three 250VAC output receptacles (CS-6369), 50 amps

Three auxilliary circuit breakers, 250V @50 amps

Two 125 VAC output receptacles, (GFCI), 20 amps

Two GFCI circuit breakers, 120V@ 20amps

Five output terminal lugs (3Ø power)

Control Box

The “Control Box” is provided with the following:

3-Pole, 250 VAC, 175 amp Main Circuit Breaker

Automatic Voltage Regulator

Current Transformer

Emergency Relay

Open Delta Excitation System

The DCA-70SSJU Series 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

The DCA-70SSJUand DCA-70SSJU2are powered by a 4 cycle, water cooled, turbocharged JOHN DEERE Model 4045TF150 Diesel Engine. This engine is designed to meet everyperformancerequirementforthegenerator.ReferenceTable 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.

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 varia- tion 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 5) as a guide for selecting proper extension cable size.

PAGE 22 — DCA-70SSJU SERIES — OPERATION AND PARTS MANUAL (STD) — REV. #5 (06/03/03)