3.8kVA Isolated Online UPS

TX91-3.8K 3.8kVA /3800VA Isolated Online UPS

A Galvanic isolation in UPS (Uninterruptible Power Supply) systems is crucial, especially in laboratory settings, for several reasons:

  1. Electrical Safety: Lab equipment often operates at different voltages and frequencies. Galvanic isolation ensures that there’s no direct electrical connection between the input and output of the UPS. This prevents any potential electrical hazards like shocks or short circuits.
  2. Noise Reduction: Galvanic isolation helps in reducing electrical noise or interference. In a lab environment where sensitive equipment like measurement instruments or analytical devices are used, even small fluctuations or disturbances in power can impact accuracy. Isolation helps in maintaining a stable and clean power supply to these devices.
  3. Ground Potential Differences: In a laboratory setup, there can be various ground potentials due to different grounding systems or electrical connections. Galvanic isolation prevents the flow of ground loop currents between equipment, which could cause signal distortion or damage sensitive components.
  4. Equipment Protection: Lab instruments are often expensive and delicate. Galvanic isolation can protect them from power surges, voltage spikes, or transient disturbances that may occur in the main power supply. By providing a barrier, it ensures that any electrical faults or disturbances on one side of the isolation barrier do not propagate to the other side.
  5. Compliance: In some cases, regulatory standards or safety guidelines may mandate the use of galvanic isolation in certain lab equipment, especially those used in critical applications or hazardous environments.

Overall, galvanic isolation in UPS systems ensures the reliable and safe operation of laboratory equipment, minimizes the risk of damage or inaccuracies, and helps in maintaining the integrity of experimental results.

Purchase with confidence!  The TX91 UPS is backed by an industry leading 3-year product warranty and a $50,000 Load Protection Policy.

For questions or quotations please contact us via Chat, Phone or email at sales@republicpowersystems.com 

Product description

Features of the TX91 3.8kVA Isolated Online UPS  include:

The TX91 3.8kVA Isolated online UPS provides the cleanest power in the most demanding conditions. The TX91 galvanic isolation transformer prevents common mode noise which is left exposed by typical transformer-less online designs.

Galvanic isolation keeps the electrical output from the UPS physically isolated from input power coming into the UPS.  Power isolation is achieved by using isolation transformer.  No output electrical wiring comes in contact with the input power cabling.

  • CAPACITY: 3.8 kVA / 38000 VA/ 3800 Watts                                                                                            CLICK HERE TO CALCULATE YOUR POWER REQUIREMENT
  • INPUT VOLTAGE: 208VAC (200VAC, 220VAC, 230VAC, 240VAC optional)
  • RUNTIME: 15 minutes @ 100% and 37 minutes at 50% load draw
  • EXTENDED RUNTIME: Up to 265 minutes @ 100% and 572 minutes @ 50% load draw (with additional external batteries)
  • OUTPUT VOLTAGE: 240/120VAC or 230/115VAC
  • EFFICIENCY: Up to 97% ECO mode, 91% online mode
  • UPS TOPOLOGY : Galvanically Isolated Online
  • MANAGEMENT: Intelligent battery management, remote control and monitoring options that are network manageable
  • WARRANTY: 3 years electronics, 3 year battery warranty (USA and Canada)

Benefits of the TX91 3.8K Online UPS include:

UNITY OUTPUT POWER FACTOR: TX91 systems provide more real capacity for high density loads

MAINTENANCE BYPASS: Manually transfer critical loads from UPS power to utility power, enabling TX91 UPS maintenance

GALVANIC ISOLATION TRANSFORMER: Eliminates common mode noise and the need to install expensive dedicated circuits and provides power conditioning during normal and bypass operation

EXTENDED BATTERY RUNTIMES: Optional 580W internal batteries (XR models) and external battery cabinets and chargers can be added for extended runtime

STATIC SWITCH: Automatically transfers output from inverter to the isolated bypass source in the event of an overload or fault

SURGE VOLTAGE LET-THROUGH: < 10V normal mode (L-N), < 0.5V common mode (N-G) when subjected to 6kV ANSI/IEEE C62.41 Cat. A

HOT SWAPPABLE INTERNAL BATTERY TRAYS: Easy to replace without interrupting the load

SURGE VOLTAGE WITHSTAND CAPABILITY: ANSI/IEEE C62.41 Category A & B, 6kV/200 & 500A, 100kHz ringwave

$50,000 LOAD PROTECTION POLICY: Offers protection against damaged connected equipment

Power Protection provided by the TX91-3800VA Isolated Online 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 Power Input

The TX91 3.8kVA Isolated Online UPS supports incoming wide AC power input. The automatic voltage regulator (AVR) 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 the battery life of the UPS.

Galvanic Isolated UPS Toplogy

Galvanic isolated UPS topology refers to a design configuration in which there is complete electrical isolation between the input and output sides of the UPS system. This isolation is achieved through the use of a transformer or similar isolation device.

Galvanic Isolated UPS Topology

Galvanic Isolated UPS Topology

In a typical galvanic isolated UPS system:

  1. Input Stage: The input stage of the UPS rectifies the incoming AC power from the mains supply and converts it to DC power. This DC power is then used to charge the battery bank and power the inverter stage.
  2. Isolation Transformer: The key component that provides galvanic isolation is the isolation transformer. It is placed between the input and output sides of the UPS. The transformer electrically separates the input and output circuits while allowing power transfer through electromagnetic induction.
  3. Inverter Stage: The inverter stage converts the DC power from the battery or rectified mains supply back into AC power. This AC power is then used to supply the connected equipment on the output side of the UPS.
  4. Output Stage: The output stage of the UPS provides power to the connected load. It may also include additional filtering or conditioning components to ensure a clean and stable power supply to sensitive equipment.


Technical Specifications



Rated Power Capacity (Apparent/Active)

3.8kVA / 3800VA / 3800W

Voltage/frequency range

208VAC (200VAC, 220VAC, 230VAC, 240VAC optional)


240/120VAC or 230/115VAC

Battery Module

(20) 12V 9AH / (20) 12V 580W

Dimensions & Weight

9.9" x 23.3" x 32.4", 272 lbs

Output Connections

120V: 5-15/20R 240V: L6–30R, L6–20R, 6–15/20R, C19
Terminal blocks or optional PDU


UL1778, cUL, FCC Class A, RoHS


RS-232, EPO, RS485, USB, dry contact, (2) slots for optional cards (Web/SNMP, Relay/dry contact)


3 years battery warranty (USA and Canada)
3 years electronics

Whats in the box

User manual, RS-232 communication cable, shutdown software

Available Options

5 year extended warranty, output PDU, input L6–30P cord

Estimated Run-Time

Battery Run Time Graph