As the market leader in 250.1-500 kVA UPS*, the 9900B is one of the best UPS for data centers, ideal for colocation,
healthcare, and mid-to-large enterprise applications.

480V / 300, 500, & 750 kVA

The 9900B UPS from Mitsubishi Electric is a three phase, online double-conversion system, featuring our world-renown IGBT technology for enhanced UPS performance and reliability. As the best-selling UPS in the 250.1-500 kVA range*, the 9900B UPS delivers all-around dependability:

  • 97% efficiency in double conversion
  • Small footprint create more data center real estate for income-generating IT equipment
  • Ease of maintenance via front access to pull-out trays
  • Low heat rejection to save on cooling costs
  • Industrial fans
  • Capacitors with a 15-year design life
  • Distributed bypass design for multimodule operation

The 9900B UPS is Lithium Ion, VRLA, VLA, and Pure Lead compatible for greater flexibility.

Unparalleled reliability. Maximum Uptime.

Mitsubishi Electric delivers the highest reliability among backup power equipment suppliers. Our robust technology is designed to deliver continuous power in the most demanding environments - and it’s not just estimated. The 9900B has a sustained load carrying capacity of 99.9995% of their actual operational history.

All the power. Smaller Footprint.

UPS for data centers demand a small footprint so more white space can be devoted to IT and other revenue-generating equipment. The 9900B model UPS delivers unparalleled reliability and high efficiency at a smaller footprint than other competitor units.

Benefits to the customer include -

  • Excellent output voltage control
  • Dynamic inverter response
  • 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.

Low maintenance. Consistent quality.

Designed with not only reliability, but also maintenance in mind, the various system components of the 9900B UPS minimize or help ease system maintenance. Low-effort accessible upkeep systems ensure consistent quality operation for the lifetime of the system. Below are just a features that make the 9900B easy to maintain:

  • Static switch with wrap around contactor for increased reliability and added redundancy
  • High quality industrial grade fans to provide longer life and enhanced dependability
  • 15-year capacitor life for increased reliability and decreased maintenance costs
  • Draw out trays for ease of maintenance and decreased downtime
  • Flexible input/output cabinet

With these specifically designed features, mean-time-to-repair, including any replacement of components, does not exceed four hours.

The best-selling UPS in the 250.1-500kVA range*

There’s a good reason the 9900B is preferred by our customers in the financial, medical, and cloud computing sectors: It’s a workhorse with stellar performance rating across markets.

Application: Data Centers, Edge Data Centers

Markets: Cloud Computing & Colocation, Financial Sector, Hospital & Healthcare

Enterprise data centers supporting financial firms employ the 9900B, helping them deliver excellent customer service essential to maintaining a loyal customer base. Hospital and healthcare providers demand readily accessible and transmittable patient information. They choose Mitsubishi Electric UPS for their data centers because they are committed to ensuring their critical power infrastructures are the gold standard of reliability.

Regional edge data centers in non-major cities of the Tier II and Tier III levels, such as Birmingham and St. Louis, leverage the 9900B to deliver backup power in remote installations. These edge data centers process data as close to the end user as possible, thereby reducing latency issues common to larger, but more distant, data centers. They require a UPS with sufficient power and a small footprint.

Application: Medical Equipment

Markets: Hospital & Healthcare

Medical institutions deploy the 9900B to protect the critical power systems that fuel urgent care. Our UPS ensures essential equipment is dependable and expensive procedures are successfully performed without interruption or damage.

These are just a few of the markets where the power, size, efficiency, and reliability of the 9900B makes it the best UPS for the job. Contact us today to see how we can support your mission critical power needs with a 300kVA, 500kVA or 750kVA UPS from Mitsubishi Electric.

Other Features

  • Superior power control (IGBT 3 level topology)
  • True online double conversion
  • Unity PF Output
  • Advanced Circuit Topology & PWM
  • Low Input Harmonics
  • 1.1:1 generator compatibility
  • Parallel up to 8 Units with a CLC
  • OSHPD Seismic Certification Option
  • Lithium ReadyTM



  • 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

Why choose a Mitsubishi Electric UPS?

9900B UPS offers an unbeatable performance guarantee.

While individual unit efficiency can fluctuate slightly under various operating conditions, Mitsubishi Electric is so confident in the efficiency of our product when optimally installed onsite, that we offer a performance guarantee.

When installed, the AC/AC efficiency of the 9900B UPS will not be <1% below the efficiency published in our factory specifications. This will be verified by a performance test - either at our factory or an acceptable test site - with a module operating on inverter and the battery disconnected. In the event the 9900B fails to comply with this guarantee in a verified performance test, Mitsubishi Electric will refund the purchaser an amount up to a maximum $10,000 per year for three years. Please note that all efficiency curves published on this site are for the respective UPS operating in true online double conversion (aka VFI).

Compatible battery power for a 300kVA, 500kVA or 750kVA UPS.

Mitsubishi Electric offers various DC power solutions with both lithium ion and VRLA battery cabinets, which you can learn more about below. With respect to lifespan and operation efficiency, new lithium ion batteries now outlast traditional VRLAs. They’re also getting smaller, with the new BCL04-BB cabinets being the perfect size to support applications that require a small footprint.

For a deeper dive into all possible solutions, review our UPS Batteries & DC Power Solutions.

9900B Success Stories

Read the unique stories of our valued customers and discover why Mitsubishi Electric was chosen to protect their critical infrastructure.

Why we partnered with Mitsubishi.

Keeping the mission to lower PUE in mind, Element Critical chose Mitsubishi Electric’s 9900B 750kVA UPS for their expansion project at their Chicago One location and a retrofit at Silicon Valley.

Retrofitting with a Mitsubishi Electric 9900B UPS.

In the fall of 2020, Dave Jones, Regional Sales Manager at Computer Protection Technology (CPT), retrofitted a customer’s aging competitor unit with a Mitsubishi Electric 9900B UPS.

Quality engineering.

In 2009, after decades of operating experience – and with a growing installed base of 100-plus UPS systems from five manufacturers – the operations team set a goal: Maximize ROI and boost reliability.

Customer-ready in 90 days.

CoreSite had an aggressive set of targets as construction began on a 102,000-square-foot co-location facility in Santa Clara, California.

Sky-high customer service.

When a critical UPS made by a Mitsubishi competitor failed at one of ViaWest’s data centers in Dallas, ViaWest engineers instantly huddled with the manufacturer’s rep and maintenance provider.

9900B UPS Specifications

With a kVA range of 300 to 750, the 9900B UPS is readily equipped to maintain critical power in large enterprise applications. Mitsubishi Electric can customize a complete and seamless backup solution to suit your needs.

Review the various UPS peripherals including maintenance bypasses, DC energy solutions, & communication options below.