20kVA Scalable rackmount UPS Double Conversion Online

R91 20kva Three Phase UPS

18kW of efficient and reliable power in just 5U of rack space the R91 provides industry leading power density and efficiency. Continuous online double conversion or ECO mode can be user selected. The R91 programmable battery charger and advanced rectifier power walk-in features help optimize compatibility with numerous source types and ratings.

  • Voltage can be configured for 415/240V, 400/230V, or 380/220V
  • Parallel up to 4 modules for up to 80kVA of power
  • Online double conversion or ECO mode operation
  • Programmable Rectifier power walk-in
  • UL 1778, CE, FCC A listings
  • 2 years depot warranty (USA only)
  • For questions or quotations please contact us via Chat, Phone or email at sales@republicpowersystems.com 
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Product description

Features of the R91 20kVA scalable rackmount UPS include:

The R91 is a 20kva scalable rackmount UPS that provides a flexible power protection solution.  The redundant design combines continuous power availability and the highest efficiency for mission critical applications.  Up to four 20kVA power supplies can be connected in parallel providing 80kVA of power.

This system is a three phase input output high-frequency online UPS. The UPS protects against power failures, power sag, power surge, under-voltage, over-voltage, line noise, frequency variations, switching transients, and harmonic distortion which can all cause critical problems to supported sensitive electronic equipment in the market today.

Capacity, redundancy, battery runtime, and output receptacles can all be customized to meet your specific needs. Hot swappable battery modules provide rapid maintenance, repair and upgrades.

  • CAPACITY: 20 kVA /20000 VA /18 kW                                                                                CLICK HERE TO CALCULATE YOUR POWER REQUIREMENTS
  • POWER FACTOR: High output power factor of 0.9
  • VOLTAGE INPUT: Three-phase + neutral + ground 210-478VAC, 40-70Hz
  • VOLTAGE OUTPUT: 415/240VAC, 380/220VAC, 400/230VAC (selectable)
  • EXPANDABLITY: Parallel for capacity or redundancy up to 4 UPS systems
  • EFFICIENCY: 99% efficiency in single module systems in ECO mode
  • WARRANTY: 2 years depot warranty (USA only)

Benefits of the R91 UPS include:

Reduce power consumption and increase end to end efficiency with this powerful three-phase uninterruptible power supply.  Designed for high density critical loads, the R91 20kVA UPS delivers industry leading reliability, efficiency and flexibility. R91 UPS has a high capacity internal charger model available for connection to matching external battery packs or large external battery systems.

HIGH POWER DENSITY: 20kVA/18kW of protection and backup power in just 5U of rack space

EFFICIENCY: Up to 99% efficiency in ECO mode and 94% efficiency in online mode

PROGRAMMABLE BATTERY CHARGER:  Charging rate, boost and float voltages

ADVANCED LCD DISPLAY: Full color display of power metering for individual phases and system summary


TEMPERATURE COMPENSATION: Temperature compensated charging to prolong battery life and help reduce replacement costs

ADJUSTABLE POWER WALK-IN: Provides programmable linear reloading of AC source

Power Protection provided by the R91 20kVA UPS:

  • Power conditions such as electrical surges and sags
  • Total loss of electrical power or hard power “re-boots”
  • Unstable incoming power caused from outdated or faulty electrical wiring and or power distribution equipment
  • Harmonic interference from neighboring “high power draw” equipment
  • Severe weather events such as lighting storms, ice and snow storms and downed power lines
  • Unstable power generation from local utilities or on-site generation

Click here to learn more about the TOP 10 POWER ISSUES and UPS power protection features

Wide Input Voltage 

The R91 18kW Scalable rackmount UPS supports incoming wide AC power input. This feature protects the UPS and connected equipment from adverse voltage conditions. This wide AC input capability can offer sag and surge protection without engaging the backup batteries of the UPS. This will reduce the stress on connected critical equipment and extends battery performance and life of the UPS.

Double Conversion Topology

Double Conversion Technology

Double Conversion Technology

The R91 20000VA scalable rackmount UPS is a Online Double Conversion UPS providing the ultimate in clean and stable electrical power.  Incoming AC power is fed to the UPS’ rectifier converting it from AC to DC power. The converted DC power routes to a battery charging circuit and to the inverter for conversion back to AC power. The resulting “double converted” electrical power is pure sine wave output providing near perfect electrical power for connected equipment.

To ensure 7/24 up time the double conversion UPS topology utilizes a static “bypass switch” within its circuity design. If the R91 20kVA scalable rackmount UPS detects a system failure, audible alarms will sound as the bypass switch is engages. This routes power around the failed UPS and ensures critical load power to target equipment.  This very important feature allows for 100% up time for critical equipment while the UPS can be repaired or replaced.

In the event of total power failure, the UPS will power off the rectifier when the loss of power is detected. The UPS’ internal backup batteries will continue to supply DC power to the inverter. There is no transfer time as the transition to battery power is instantaneous. This feature provides true uninterruptible power to mission critical equipment.


Technical Specifications



Rated Power Capacity (Apparent/Active)


Voltage/frequency range

210–478VAC, 40-70Hz

Efficiency (Maximum%)

Online mode up to 94%; ECO mode up to 99%

Overload Capacity

110% for 60 min; 125% for 10 min; 150% for 1 min; > 150% immediate

Max charging (adjustable)

<4 hrs to 90%

Battery Module

17.4 x 33.9 x 7.0 in (4U)

Dimensions & Weight

17.4 x 22.8 x 5.2 in

Maximum Capacity


Output Connections

Terminal Block (Hardwire)

Operating Temperature

0–40°C (32–104°F)**

Operating Elevation

11,500 ft above sea level


UL-1778 (TUV)


RS232, RS485, EPO, parallel port, external Web/SNMP (optional)


2 years depot warranty (USA only)

Whats in the box

User manual, RS232, shelf kit, Muser monitoring software



Estimated Run-Time

Battery Run Time Graph