Electricity is used to power everything from personal computers to businesses. Therefore, it is critical to have a reliable backup power supply in any situation. Power outages or fluctuations in voltage can cause damage to your devices and disrupt your work. UPS (Uninterruptible Power Supply) units provide a backup source of power, however, not all UPS units offer the same protection.

If you need to set up a home office, maintain your IT infrastructure, or use sensitive industrial equipment, knowing the differences between the two common types of UPS units (Online and Offline) will assist you in determining which unit is better suited to your particular application.

What Is an Offline UPS?

An Offline UPS is essentially a simple and cost-effective backup power technology designed for basic operation and provides battery backup to the end-user only when there is a disruption in the power supply. An Offline UPS is also referred to as “Standby UPS”. During normal operation, an Offline UPS is connected directly to the electrical service or main supply. The battery of an Offline UPS remains in a ready mode and is only activated during times of electrical power disruption.

The unique feature of an Offline UPS system is the ability to switch from one source of power to another when needed. In practice, switching power sources takes only a fraction of a second, typically less than a few milliseconds. For some devices using Offline UPS technology, this inactivity may be undetectable; for others, it may cause flickering or momentary dimming of lights during the transfer from AC power to the battery-backed supply.

What Are the Benefits of Offline Uninterruptible Power Supplies (UPS)

The offline UPS is useful for places that typically experience short-term outages and where the devices connected to them can withstand a minimal delay before receiving power back.

Typical uses include:

• Computers and monitors in homes
• Standard office set-ups
• Scanners and printers
• CCTV cameras
• Wireless routers.
• Pros of Offline UPS
• Less expensive than online UPS
• Use less electricity
• Simple to install and maintain
• Best suited for everyday appliances.

Cons of Offline UPS

• Transfer delays during blackouts are brief

• Little protection against voltage spikes, although some may protect from surges; 
•  Provide minimal power line conditioning; and are not recommended for sensitive high-end equipment.

What Is an Online UPS?

Online UPS systems are sometimes referred to as “double conversion” UPS systems because they provide the highest level of protection for any connected loads. Online UPS systems use tiered, time-based battery management and do not depend directly on the input/test bed of AC power from the grid to power the connected loads. Online UPS systems repurpose AC mains electricity, converting it from AC to DC to charge the internal batteries of the UPS, then converting DC back to AC to provide power to the connected equipment.

The most significant advantage of Online UPS systems is that they provide continuously conditioned, stable, clean (clean power), regardless of the quality of the input electrical supply source. Therefore, Online UPS systems do not experience the delay in switching from the utility mains to the battery due to the fact that the inverter is always supplying power to the equipment during a utility outage, resulting in no delay in response time during an outage.

Where Is Online UPS Used?

An Online UPS is suitable to provide power protection for mission-critical equipment or those that cannot withstand even the briefest interruption in power.

Common applications of the Online UPS include:

1. Hospitals and medical equipment
2. Banking and ATM services
3. Data centers and IT services
4. Telecommunications
5. Industrial
6. Laboratory equipment

The Advantages of an Online UPS are:

1. No transfer time
2. Exceptional voltage stability, filtering capabilities
3. provides the best protection for mission-critical, or highly sensitive electronic systems
4. Protects against electrical interference, surges and voltage fluctuations

The Disadvantages of Online UPS include:

1. Higher initial investment/costs than Offline UPS units
2. Higher heat output and possible need for cooling
3. Slightly more electricity is used.

Which One Should You Choose?

The determination of which type of UPS equipment you need can depend on many variables including the intended use of the UPS equipment, your financial constraints and hardware/protected devices.

If you’re looking for a simple backup solution for your home or small office then using an “Offline UPS” would be adequate for you:

• Basic use.
• Non-critical / Not sensitive electronic devices.
• Cost-effective.

If you have critical systems (e.g., server computer systems, medical equipment, industrial equipment) that require uninterrupted power supply, you should consider an “Online UPS”:

• Used to protect critical systems.
• No power interruption (even 1 microsecond) = damage downtime.
• Maximum power conditioning and protection.

Many companies utilize both UPS types strategically. An “Online UPS” can be used to protect high-priority/electrical systems, while an “Offline UPS” can be used for secondary non-critical systems.

Conclusion

An Online UPS, as opposed to an Offline UPS, protects your equipment from power problems in two distinctly different ways, which are designed for different usage. In general terms: the Offline (or Line-Interactive) type of UPS provides affordable day-to-day use protection while Online UPS provides an uninterrupted premium quality level of power protection for critical applications.

If you are still unsure about which type of power back up option is right for your situation, having a professional evaluate your unique needs and requirements can be beneficial in helping to minimize the risk of incurring unnecessary costs or the potential risk of damaging critical equipment. Capital Power Backup has qualified Power Backup Professionals who can provide you with valuable expertise and all of the most popular, reliable brands of UPS Systems for both types of applications, as well as UPS Rental Services, and superior service continuing support for their customers.