Product Review (March 2005) - APC
SUA750RM2U Smart-UPS 750VA / 480W
USB & Serial 2U Rack

UPS (Uninterruptable Power Supply) units have been around for some time, particularly with computer and network users. The need for clean, uninterrupted power has also found its way into the area of home entertainment, particularly with products such as video projectors that use very hot lamps. In addition, products sensitive to line noise such as plasma displays can benefit from high performance power products. Conventional power conditioners have been widely available for A/V electronics from a variety of manufacturers, yet do little for brownouts (voltage sags) and complete power outages. For many, this might not be a problem, but if you happen to own an expensive LCD or DLP projector, you might have reason to be concerned. It is certainly possible to damage the lamp or projector if power is suddenly lost while the unit is running hot and doesn't have time to properly cool down from its operating condition. As luck would have it, we had the opportunity to review APC's Smart-UPS 750VA/480W (SUA750RM2U) rackmount unit, which was a good match for our high definition DLP projector.

APC (American Power Company) has been making UPS units for over 20 years and targets home/small offices, business networks, access providers, and data centers & facilities. While this unit is geared more for networks and servers, it also provides reliable power for moderate power needs. In addition, the Smart-UPS produces a true sine wave instead of the modified sine wave version that produces undesired harmonics. Weighing nearly 50 pounds, the SUA750RM2U is actually considered light for a rackmount style UPS. The unit we reviewed here has the lowest power rating in the Smart-UPS series family with the largest offering 5000VA/3750W and weighing more than 200 pounds. We chose this unit primarily because we wanted a UPS capable of supplying power to a DLP or LCD projector for sufficient time to shut it down in the event of power loss. The Smart-UPS comes complete with rack mounting brackets and support rails for standard 19" racks.

Front Panel
The front panel has separate On and Off buttons for power as well as separate five-step indicators for the load and the battery supply capacity. The Online indicator illuminates when the incoming utility power is available to the UPS. The AVR Trim illuminates when the UPS is compensating for high utility voltage and the AVR Boost illuminates when the UPS is compensating for low utility voltage. If the UPS becomes overloaded the Overload light will illuminate. The On Battery Power light turns on when the unit is running on battery power and emits four beeps every 30 seconds to let the user know that the battery is discharging. The Replace Battery indicator and Battery Disconnected indicator are the same light, but emit different beeps based on the problem. If the battery is disconnected, the unit will emit a beep every two seconds. Upon powering the unit on, the Smart-UPS performs a battery test to check the health of the system.

Rear Panel
The rear panel consists of six protected outputs with a 10 amp circuit breaker. Either a USB or an RS232 serial interface is used to communicate with the UPS processor for setting parameters and getting status of the unit. We opted to use the USB interface connected to our laptop. A red LED illuminates if there is a problem with the incoming utility power. The long power cord was a nice addition. The Sensitivity button has a green LED that changes intensity to reflect the low, medium and high sensitivity setting. This chassis is also used for higher powered UPS units which consume more power because the fan vent located on this unit was unoccupied. If the user wants to have ethernet connectivity, the unit has a blank panel revealing the SmartSlot used for the optional network monitoring card.

The inside of the Smart-UPS chassis holds a large circuit board that contains the charging electronics for the batteries and the power inverter that converts battery supply to full-wave 60 Hz AC. The Philips-based microcontroller sits in a socket, making it easy to swap out in the event of a firmware upgrade. The processor is responsible for monitoring the vitals of the unit and communicating with the USB, RS232 and SmartSlot interfaces. The weight of the UPS is largely due to the heavy lead-acid batteries installed in the removable tray and the large iron core transformer used in the power inverter circuitry. The APC design appears to be quite efficient and does not require a cooling fan to keep the electronics from overheating during operation.

Battery Pack
Two large 12VDC lead-acid batteries hold the power reserve and are mounted on a removable tray that slides out of the front of the unit. Four screws hold the tray in place. The slide-out tray makes it very easy for a service technician to replace the battery pack even when the UPS chassis is installed in a standard 19" rack. Additional battery packs are available from APC through their website. A tethered rope tied to the cable connector allows the user to quickly unplug the removable pack. The unit we reviewed had the batteries wired in series with an inline 60 amp fuse for safety.

PowerChute Software
What makes this UPS smart is the microcontroller contained within the unit. This combined with APC's PowerChute Business Edition software gives the Smart-UPS powerful monitoring capabilities. The version of software i
ncluded with the Smart-UPS is a basic 5-node edition of PowerChute that can be upgraded to include more nodes. The software has three sections defined as Status, Power Event Analysis and Voltage Analysis. The Status window provides the Hostname, IP Address, Status, UPS Model, Serial Number, Firmware Revision, Battery Replacement Date, Man Date, Location, Contact, Environment Monitor (optional), Agent Version and Agent Operating System. Each of these items can be enabled or disabled in the Configure Columns submenu or by right clicking any of the columns on the table. The user can setup the software to check for updates manually or automatically.

The Power Event Analysis screen shows statistical data that characterizes the incoming utility power. Events such as Power Failed, Low Battery, Extended Undervoltage, Extended Overvoltage, Frequent Undervoltage and Frequent Overvoltage are displayed over a period of time. The user can set the history to cover the Last Day, Last 7 Days, Last 30 Days or Last Year. This information can help determine if the threshold voltages need to be adjusted to prevent the UPS from switching back and forth due to incoming power being marginally high or low. In any event, the data is useful in determining problems.

The Voltage Analysis window displays the incoming voltage as a function of time. Similar to a strip chart recorder, older data moves to the left as the new data is updated. This allows the user to see the voltage history in the form of a graph. The time displayed is selectable by the user (Last 30 Minutes, Last Hour, Last 6 Hours, Last 12 Hours or Last Day). The High and Low Transfer Voltages are user selectable and are displayed on the same chart. This makes it easy to see if the incoming power is marginally close to the transfer voltage. If so, it may be best to move the threshold point farther away from the incoming voltage to prevent inadvertent tripping of the UPS unit. This is assuming the electronics connected to the UPS can handle the voltage tolerance defined by the user. Threshold values are changed in the Device Properties menu under the Power Parameters section.

Device Properties
In addition to the Power Parameters, the Device Properties menu gives the user information about the UPS units connected to the network. The Summary screen displays the general information about the connected UPS including the Model Number and Serial Number. The UPS Status screen displays the current load on the unit and whether the UPS is running from utility power or battery power. Also displayed here is the Internal Temperature, Output Voltage, Input Voltage and Output Frequency. The Battery Status screen shows the remaining capacity, Battery Status, Battery Voltage, Runtime Remaining and when the battery was replaced.

A full Event Log is also provided with the last event and time and date. The software is designed to monitor an entire group of UPS unit(s) under a single program. PowerChute has the ability to execute a command file before shutting down the operating system when a power problem is detected. In this case, the user needs to specify the amount of time required to run the command file. The system can send emails, pages and network broadcast notifications.

Utility Power
We measured the output voltage waveform from the Smart-UPS when the unit was plugged into an active power outlet as well as when the power was removed from the unit. In both cases the UPS was powering a 100-watt incandescent lamp as a light load. Interestingly enough, we saw more waveform distortion when connected directly to the utility power. The unit bypasses the internal power inverter when the utility voltage is within an acceptable range. If the utility voltage falls outside of the specified range, the UPS switches to the self-generated 120VAC. The top and bottom waveform peaks exhibit distortion. We are not sure where this distortion was coming from, but it did appear in other places within the house. Once the plug was removed from the wall and the UPS inverter kicked in, the output waveform immediately looked clean.

Smart-UPS Power
As the photo indicates, the waveform no longer exhibited obvious distortions. Unfortunately, this UPS does not always supply AC from its internal generator, but instead switches from utility power to the internal generator when power is out of range or lost completely. There is also a short lag or dropout when this occurs which can affect some equipment in rare cases. We tested the Smart-UPS with our DLP projector to see how well the unit performed in real-world conditions. The Smart-UPS output kept the DLP projector running giving us more than enough time to shutdown the unit.

The Smart-UPS is a nice design that provides true sinewave AC backup power to connected components. While many switching power supplies work fine with stepped AC waveforms, we prefer to keep the harmonics out of the powerline. We just wish we had the AC generated from the Smart-UPS 100% of the time regardless of the input. The PowerChute Business Edition software included with the unit provides some excellent control and monitoring of the connected equipment and is especially powerful at managing multiple UPS units when they are connected. APC has also addressed the need for future maintenance by making it easy to service the batteries once the unit is installed into a large chassis. The AC waveform looked near ideal with our measurements and gave us confidence that our components would survive a power outage. APC's optional web card ($299) further enhances the capabilities of the unit with full ethernet connectivity.

- Kevin Nakano

OPPO BDP-83SE Blu-ray Player

OneCall: Your Home Theater, Digital Camera, and HDTV Experts

Review System

Projector: Optoma H77 High-Definition HD2+ DLP™ Projector
Stewart Filmscreen 100" FireHawk Screen on a Luxus Deluxe ScreenWall
Video Processor/Scaler: Anchor Bay Technologies DVDO iScan HD A/V Processor
Preamplifier/Processor: Parasound AVC-2500U THX-Ultra DTS/DD Preamp/Processor
Amplification: Parasound HCA-2205AT THX-Ultra Five Channel Amplifier
Bass Management: Miller & Kreisel BMC Mini 5.1 Bass Management Controller
Front Speakers: Miller & Kreisel S-150THX (L+R) and S-150AC (Center) Speakers
Rear Speakers: Miller & Kreisel SS-250 Tripole® Surround Speakers
Subwoofer: Two Miller & Kreisel MX-350THX MkII THX-Ultra Push-pull Subwoofers
Room Treatments: Echo Buster panels and Bass Buster towers
Set-top Box: Samsung SIR-T165 Terrestrial HDTV Receiver with DVI
DVD/CD/SACD Player: Sony DVP-NS900V DVD/CD/SACD Player
DVD Audio/Video Player: Kenwood Sovereign DV-5900M 400-Disc DVD Changer

D-VHS VCR #1: JVC HM-DH30000U D-VHS High-Definition D-Theater VCR
D-VHS VCR #2: Marantz MV8300 D-VHS High-Definition D-Theater VCR
A/V Cables: Ultralink Platinum and Advanced Performance Series Cables
DVI Cable: AudioQuest DV-1 20m DVI-D Cable
DVI Extender: Gefen HDTV Extender
HDMI Cables: Accel Corporation HDMI Adapter and Cables
Power Conditioning: Panamax MAX® 5510 ACRegenerator
Video Generator: Sencore VP403 SDTV/HDTV Video Pattern Generator
Color Analyzer #1: Sencore CP5000 ISF Certified All-Display Color Analyzer
Color Analyzer #2: Milori ColorFacts Professional with GretagMacbeth Eye-One Pro

Review at a glance

APC - SUA750RM2U Smart-UPS 750VA USB & Serial


  • Disconnected battery notification
  • Front-access servicing
  • USB and Serial (RS232) Connectivity
  • General Features

  • Adjustable voltage sensitivity
  • Adjustable voltage-transfer points
  • Audible Alarms
  • Automatic restart of loads after UPS shutdown
  • Automatic self-test
  • Boost and Trim Automatic Voltage Regulation (AVR)
  • Cold-start capable
  • Generator Compatible
  • Hot-swappable batteries
  • Intelligent Battery Management
  • LED status indicators
  • Network manageable
  • Power conditioning
  • Predictive failure notification
  • Resettable circuit breakers
  • Safety-agency approved
  • Serial Connectivity
  • SmartSlot
  • Temperature-compensated battery charging


  • CD with software
  • Rack Mounting Brackets
  • Rack Mounting support rails
  • Smart UPS signalling RS-232 cable
  • USB cable
  • User Manual

    Technical Specifications

  • Output Power Capacity: 750 VA / 480 Watts
  • Max Configurable Power: 750 VA / 480 Watts
  • Nominal Output Voltage: 120V
  • Output Voltage Distortion: less than 5% at full load
  • Output Frequency (sync to mains): 57-63Hz for 60Hz nominal
  • Crest Factor: up to 5:1
  • Waveform Type: Sinewave
  • Output Connections: (6) NEMA 5-15R
  • Nominal Input Voltage: 120V
  • Input Frequency: 50/60 Hz +/- 3 Hz (auto sensing)
  • Input Connection Type: NEMA 5-15P
  • Input Voltage Range for Main Operations: 82 - 144 V
  • Input Voltage Adjustable Range for Mains Operation: 75 - 154 V

    Company Information
    APC Corporate Headquarters
    132 Fairgrounds Road
    W. Kingston , RI 02892
  • Part Number: SUA750RM2U
    MSRP: $419.00
    Source: Manufacture Supplied
    Warranty: 2 years repair or replace
    Equipment protection policy Lifetime: $150,000

    Weight: 48 pounds
    Rack Height: 2U
    Dimensions: 4" x 19" x 18" (HxWxD)

    Technical Support: 800-555-2725


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