9900B Three Phase UPS

The Best Selling UPS in its range

480V / 300, 500, and 750 kVA

Like all other Mitsubishi Electric UPSs, the 9900B is a three-phase, on-line double-conversion system and features Mitsubishi Electric's world-renown Insulated Gate Bipolar Transistor (IGBT) technology for enhanced UPS performance and reliability. It enjoys the largest install base, with just under 2000 in North America alone. The 9900B is available in 300, 500, and 750 kVA, and is Energy Star rated.

It's Time to Rethink your UPS



If downtime in your business equals disaster, Mitsubishi Electric delivers the highest reliability among backup power equipment suppliers through robust proprietary technology designed to deliver continuous power in the most demanding environments. Whereas competitors only estimate their reliability, Mitsubishi Electric’s installed base of 9900 series Uninterruptible Power Supplies have sustained load carrying capability more than 99.9992% of their actual operational history.




Hight reliability


How an IGBT power device is controlled is key to achieving optimum performance characteristics of a UPS. Utilizing a combination of high sampling rates and Direct Digital Control (DDC), the 9900B is able to provide superior performance under all load conditions.

Benefits to the customer include excellent output voltage control, dynamic inverter response, and minimal voltage distortion during full load steps without the DC source. These characteristics maximize the performance of the UPS and increase the overall reliability of components and the system.


Superior Control

Footprint Comparison

All the Power. Smaller Footprint.  

The 9900B Series UPS creates more white space by minimizing the gray space it occupies. It can handle the same load in a significantly smaller footprint than competitive models, meaning more space can be allocated o revenue generation. The 9900B also has higher power density than comparable UPSs, maximizing power output while minimizing gray space.




Footprint Comparison


Performance Guarantee

Mitsubishi Electric Power Products, Inc. (MEPPI) guarantee that the AC to AC efficiency of the UPS Module Series 9900 supplied to Purchaser will not be less than 1% below the specified efficiency published in the Mitsubishi Electric factory specification. The performance test will take place during either a factory or site acceptable test with the module operating on inverter and with the battery disconnected. 

In the event the UPS module series fails to comply with guarantee, as verified by the factory or site acceptance test, then MEPPI will refund to purchaser an amount up to a maximum $10,000 per year for three years.


  • UL 1778 (Underwriter Laboratories) Standard for UPS Equipment
  • CSA 22.2 (Canadian Standards Association - cUL Equipment)
  • IEC (International Electro-technical Commission), Semiconductor Converter Standards
  • EMI compatibility: IEC 62040-2 (category C3)

  • IEEE 587, ANSI C62.41 1991 Standard for Surge Withstand Ability
  • ISO 9001 Quality Assurance program
  • OSHPD Rated
  • Energy Star Rated

Other Features

  • True On‐Line Double Conversion
  • Unity PF Output
  • 3 level IGBT Technology
  • Advanced Circuit Topology & PWM
  • Parallel Up To 8 Units With a CLC
  • Excellent Generator Compatibility (1.1:1)
  • Low Input Harmonics
  • Small Footprint and Lightweight
  • OSHPD Seismic Certification Option
  • Lithium Ready 




9900b Mitsubishi Electric three-phase UPS model efficiency chart.

As UPS systems are often viewed as one of the biggest culprits regarding energy loss in power distribution, it makes sense to consider efficiency, along with reliability, as a primary factor in the selection of a UPS. 

Through its history of technological developments, Mitsubishi Electric has proven to be a leader in advancing efficiencies to unprecedented levels.  Beginning with the use of IGBTs for converters and inverters and 3 level topology and followed by the promotion of transformerless designs, Mitsubishi Electric has long been at the forefront of offering Uninterruptible Power Supplies with the highest efficiencies available coupled with unparalleled reliability.  Mitsubishi Electric's superior expertise in optimizing power device control is evident by the flatness of the resulting curve, demonstrating high efficiency across all load levels.  Please note that all efficiency curves published on this site are for the respective UPS operating in true online double conversion (aka VFI).

DC backup power Solutions


While the UPS is the most critical piece of infrastructure in a data center, the DC power backup storage system that supports the UPS is not far behind. 

We offer various DC power solutions, and provide information on both lithium ion and VRLA battery cabinets in the Peripherals section below. 

For a deeper dive into all possible solutions, be sure to review our webpage entitled UPS Batteries and DC Power Storage Solutions or simply click here.


Peripherals & Options

While the UPS is the most critical piece of infrastructure in a data center, Mitsubishi Electric can customize a complete and seamless backup solution to suit a customer’s specific needs. A variety of peripherals including maintenance bypasses, side cars, DC energy solutions, and communication options are readily available.

Converter Input Contactor


Inverter Output Contactor

Main Power Supply Board
Static Switch and Backfeed Contactor

Bypass Output Contactor


AC Input Filter Capacitors


AC Output Filter Capacitors

Converter Trays R, S, T
Inverter Trays U, V, W