Generator Sizing Guide

UPS Generator Compatibility

Passive (also referenced as standby or off-line) and Line-Interactive

These technologies are most common for personal workstations and point of sale applications. They are typically single phase equipment with size ranges of 350 VA – 2000 VA for passive and 500 VA to 5000 VA for line-interactive.

Passive UPS’s are the simplest type. Under normal conditions AC power passes straight through to the UPS load. When the input power supply goes outside of specifications, the UPS transfers the load from input power to the internal DC to AC power inverter. Passive UPS’s do not correct for voltage or frequency deviations under “normal” operation.

Line-interactive is similar to the passive technology except it has circuitry that attempts to correct for standard voltage deviations. Frequency deviations under “normal” power operation are not corrected.

Equipment Notes:

These devices tend to be electrically / harmonically very noisy. A single small UPS is not a significant concern, but applications with multiple UPS’s can be problematic.

Passive UPS technology typically has normal tolerances of

10 – 25% on voltage and 3 hertz on frequency. If the input source goes outside of these tolerances, the UPS will switch onto the UPS battery source. Some line-interactive units may have frequency tolerances factory set to .5 hertz. These units will need to have their frequency tolerance increased to a minimum of 2 hertz.

Generator Sizing Recommendation:

Limit the total UPS loading to 15% – 20% of the generator capacity.

Double-Conversion

This technology is most common for critical load applications. Double-conversion UPS’s constantly rectify AC to DC and then invert the DC back into AC. This configuration results in an output that corrects for voltage and frequency deviations.

There are single and three phase models covering small through large applications. Most UPS applications larger than 5000 VA use double conversion technology. This approach is also the preferred technology for generator applications.

Equipment Notes:

Double-conversion UPS’s that are single phase or unfiltered three phase models tend to create a significant level of electrical/ harmonic noise. This is illustrated by harmonic current distortions that are greater than 35%. When three phase models are supplied with harmonic filters (current distortion less than 10%), this concern is no longer an issue.

Generator Sizing Recommendation:

Single phase models: limit the total UPS loading to 25% of the generator capacity.

Three phase models without filters (current distortion > 30%): limit the UPS loading to 35% of the generator capacity.

Three phase models with filters (current distortion < 10%): limit the UPS loading to 80% of the generator capacity.

Supplier(s)

Passive (Standby)

Line-Interactive

Double-Conversion

 

 

 

 

APC

Back-UPS Series

Smart-UPS Series

Symmetra Series

Liebert

PowerSure PST and PSP

PowerSure PSA and PSI

UPStation and Nfinity Series

Powerware

3000 Series

5000 Series

9000 Series

 

 

 

 

Note: Ferrups and Delta-Conversion UPS technologies not included in discussion.

7

Page 7 Page 9
Page 8
Image 8
Siemens Standby Generators manual UPS Generator Compatibility, Double-Conversion
Page 7 Page 9

Standby Generators specifications

Siemens Standby Generators provide reliable power solutions for both residential and commercial applications, ensuring that homes and businesses remain operational during power outages. These generators stand out due to their advanced engineering, innovative technology, and robust design, making them a preferred choice for those seeking uninterrupted power.

One of the primary features of Siemens standby generators is their automatic transfer switch (ATS) capability. This technology allows for seamless switching from the utility power source to the generator within seconds of a power outage. The ATS continuously monitors the incoming utility power and activates the generator when it detects an interruption. This ensures that critical appliances and systems remain functional without manual intervention.

In terms of performance, Siemens generators are equipped with continuous power ratings that cater to varying power needs. Whether it’s an essential load or a full-scale home or commercial operation, these generators can handle the demands efficiently. Most models come with powerful engines, designed for durability and longevity, ensuring they can operate under heavy loads without compromising performance.

Siemens also employs advanced noise reduction technologies in their standby generators, which significantly reduce operational noise levels. This feature is particularly beneficial for residential areas where noise compliance is essential. Additionally, the generators are engineered with vibration dampening systems, enhancing user comfort and ensuring minimal disturbance to the surrounding environment.

The fuel efficiency of Siemens generators is another remarkable characteristic. Many models utilize propane or natural gas, allowing for cleaner and more sustainable operation compared to traditional diesel generators. These fuel types not only reduce emissions but also lower operational costs over time, making Siemens generators a more economical choice for long-term power solutions.

Moreover, Siemens generators are designed with user-friendly interfaces and smart monitoring systems. Users can track generator performance, maintenance schedules, and fuel levels through digital displays or smartphone applications. This connectivity allows for proactive maintenance, reducing the risk of unexpected failures and ensuring that the generator remains in optimal working condition.

In summary, Siemens Standby Generators combine reliability, efficiency, and advanced technology to deliver unparalleled performance during power outages. With features such as automatic transfer switches, low noise operation, fuel efficiency, and smart monitoring, they provide users with peace of mind and a steady power supply whenever needed. Whether for residential or commercial use, Siemens generators are a trusted solution for maintaining essential services and comfort in the face of power interruptions.
Top Page Image Contents