To size a rental UPS system, start with the actual critical load that needs temporary protection and then confirm the required kW, kVA, voltage, phase, battery runtime and redundancy.
Do not select a rental UPS based only on the nameplate rating of the existing UPS. The current protected load may be substantially different from the capacity the permanent system was originally designed to support.
What Information Is Needed to Size a Rental UPS?
Before selecting temporary UPS equipment, establish the following:
- Actual critical load in kW
- Required kVA capacity
- Load power factor
- Input voltage
- Required output voltage
- Single-phase or three-phase configuration
- Required battery runtime
- Redundancy requirements
- Generator availability and capacity
- Indoor or outdoor installation
- Temporary connection and distribution requirements
How Do kW and kVA Affect UPS Sizing?
UPS equipment is commonly rated in kVA, while facility loads may be measured primarily in kW.
The two values are related through power factor:
kW = kVA × Power Factor
For example, an 80 kW load operating at a 0.90 power factor represents approximately 89 kVA.
This calculation is only a starting point. The selected rental UPS must also have sufficient capacity for the actual load, operating margin and any redundancy requirements.
Should You Match the Size of the Existing UPS?
Not automatically.
The existing UPS rating is useful project information, but it may not represent the current temporary-power requirement.
An existing UPS may be larger than necessary if:
- It was originally sized for future expansion
- Facility load has decreased
- Only part of the protected load needs temporary support
A larger rental may be required if:
- The facility has added load since the permanent UPS was installed
- Additional equipment will be connected during the rental period
- The temporary design requires additional redundancy
Whenever possible, use current operating-load information when sizing the rental.
Why Does Voltage Matter?
A UPS with sufficient kVA capacity is not necessarily compatible with the facility.
The rental equipment also needs to match the electrical configuration of the source and protected load.
Confirm:
- Available source voltage
- UPS input voltage
- Required output voltage
- Load voltage
- Phase
- Frequency
If the available rental equipment does not directly match the required voltage, transformers or additional temporary distribution equipment may need to be included in the project.
How Much Battery Runtime Is Needed?
UPS capacity and battery runtime are separate requirements.
The UPS must be large enough to carry the load, while the batteries must provide enough stored energy to support that load for the required amount of time.
Runtime may only need to cover:
- Generator startup
- Transfer to an alternate power source
- An orderly equipment shutdown
Other applications may require a longer period of battery support.
CI Group’s UPS Battery Runtime Calculator can help estimate runtime during initial project planning.
Does Generator Power Affect Rental UPS Sizing?
It can.
If the rental UPS will operate with a standby generator, the generator and UPS should be evaluated as part of the same temporary-power system.
Consider:
- Generator capacity
- UPS input requirements
- Voltage and phase
- Battery recharge load
- Other loads supported by the generator
- Load sequencing
- Transfer equipment
See Can a Rental UPS Be Connected to a Generator? for additional information.
Does the Installation Location Affect UPS Selection?
Yes. Available indoor space, cooling, temporary electrical connections and site access can affect which rental configuration is practical.
If indoor placement is limited, a self-contained outdoor UPS rental may be an option.
For outdoor projects, review the Outdoor UPS Rental Planning Guide: Placement, Cooling, Connections & Site Requirements.
What Should You Provide When Requesting a UPS Rental?
Providing complete information makes it easier to identify appropriate rental equipment.
Load & Capacity
- Current load in kW
- Required kVA
- Power factor, if known
- Peak expected load
- Redundancy requirement
Electrical Requirements
- Input voltage
- Output voltage
- Phase
- Frequency
- Existing distribution
Project Requirements
- Battery runtime
- Generator information
- Indoor or outdoor placement
- Project location
- Required start date
- Expected rental duration
- Electrical one-line or equipment specifications, if available
For the complete sizing process, see How to Size a UPS Rental: kVA, kW, Voltage, Runtime & Load Requirements.
What UPS Rental Capacities Are Available?
CI Group organizes available UPS rental equipment across several capacity ranges:
- 1–20kVA UPS Rentals
- 21–160kVA UPS Rentals
- 161–550kVA UPS Rentals
- 551–1200kVA UPS Rentals
- Outdoor UPS Rentals
The appropriate range should be selected only after the actual electrical and runtime requirements have been established.
Related UPS Rental Posts & Resources
How to Size a UPS Rental: kVA, kW, Voltage, Runtime & Load Requirements
Review the complete process for evaluating load, kVA, kW, voltage, runtime, redundancy and generator requirements.
How Much Does a UPS Rental Cost? What Affects Temporary UPS Pricing
Learn how capacity, runtime, voltage, rental duration, freight and installation requirements can affect rental pricing.
Outdoor UPS Rental Planning Guide
Review placement, cooling, connections and site requirements for an outdoor temporary UPS system.
Can a Rental UPS Be Connected to a Generator?
Learn what should be evaluated when temporary UPS equipment will operate from generator power.
How Long Can You Rent a UPS System?
Review how emergency, maintenance and longer infrastructure projects can affect rental duration.
UPS Battery Runtime Calculator
Estimate battery runtime based on load and UPS battery configuration.
Need to Identify the Right Rental UPS?
Start with the actual protected load, electrical configuration, required battery runtime and project schedule.
Browse CI Group UPS Rental Systems to review available temporary critical-power equipment.