The modern world is so connected that just a momentary loss of power can cause problems such as corrupted files, broken equipment, unproductive business hours, and safety issues. To address these issues, businesses and homes are using Uninterruptible Power Supplies (UPS) systems to ensure that they have consistent, usable electrical power available to operate critical systems. Unlike backup generators, the UPS automatically turns on when power goes out and will continue to supply power to critical equipment without interruption. But how can an Uninterruptible Power Supply (UPS) system supply continuous power during times of erratic electricity from the local grid?
This article discusses the internal workings, components, and protections of Uninterruptible Power Supplies that allow them to continuously supply a steady output of energy when the electric grid is not stable.
What is an Uninterruptible Power Supply (UPS)?
A UPS regulates voltage and will provide immediate backup to connected devices using stored energy. A UPS will provide backup power to connected devices without the device experiencing power loss, even for a brief duration. The UPS provides clean, regulated voltage for sensitive devices like computer systems, servers, communication devices, and medical devices, by stabilising incoming AC power, transferring energy to batteries for future use and supplying clean power from the batteries back to the device.
There are several types of unstable power conditions that you should be aware of when selecting a UPS, for example:
- Power Failure
- Voltage Dips or Sags
- Voltage Spikes or Surges
- Frequency Variations
- Electrical Noise/Distortion
- Under/Overvoltage Conditions
By stabilising the voltage, the UPS protects your equipment from the various types of unstable power conditions listed above.
The following section outlines components of an Uninterruptible Power Supply that help provide stable power:
1. Rectifier
The Rectifier is the device that converts incoming alternating current (A/C) electricity into direct current (D/C). Direct Current will be used to charge the UPS battery bank, and as power to supply UPS inverter. Several UPS systems build in filtering at this stage to eliminate line noise and other electrical distortion.
2. Battery / Energy Storage
The battery is used to store energy for the UPS to deliver when incoming A/C electricity is lost during brownouts, blackouts, etc. Batteries used in today’s UPS systems are commonly Valve Regulated Lead Acid (VRLA) batteries, lithium-ion batteries, or supercapacitors, depending on the level of performance required to maintain power to the connected equipment.
3. Inverter
The Inverter converts the stored D/C electricity (direct current) from the battery bank back to A/C electricity (alternating current), which is again conditioned to continue supplying connected equipment with clean, stable output power. In the event of a total power failure, or a total power outage, the UPS inverter will virtually instantaneously switch to battery input without any disruption in power to the equipment that is plugged into the UPS.
4. Static Switch / Transfer Switch
Ultra-fast switching from one power supply to another is made possible through the use of static switches, which are electronic devices designed to switch multiple power supplies. The static switch is manufactured to complete its operation in less than one millisecond, thereby ensuring power is consistently supplied to any connected load.
UPS Systems Sustain Stability Under Extreme Conditions
1. UPS Switches to Battery Mode Instantly to Provide Backup During Power Outages
When your primary power supply goes down, your UPS switches to battery mode almost instantaneously, which means connected devices do not shut off or reboot. This feature is increasingly important in critical environments such as data centres, hospitals and industrial automation.
2. UPS Protects Your Equipment from Voltage Issues
A UPS protects sensitive electronic equipment through the use of Automatic Voltage Regulation (AVR) and Double Conversion Technology (DCT). These technologies reduce voltage fluctuation problems and protect against overheating, unplanned shutdowns, equipment failure, and loss of data.
3. UPS systems provide Power Conditioning and Noise Filtering.
UPS Systems also include Power Conditioning and Filtering of Noise (distortion) caused by Harmonics and EMI that exist in the utility-powered electricity. Without Power Conditioning and Filtering of Noise, electrical equipment cannot function properly.
4. Frequency Stability
Some settings may experience frequency Drift as a result of Grid instability or high industrial Load types of equipment. Thus when the Input frequency Drifts (low, high, etc.) then the output of the Online UPS will remain constant (±0% of input), this protects all Electrical Devices from possible Damage due to Input Frequency Fluctuations.
5. Double Conversion Technology Provides Continuous Power
The Online/Double Conversion UPS System Uses a converter to deliver Continuous Power to the Load from the UPS Inverter. When AC Power is lost there will be a Zero Switching Delays between AC Source and UPS Backup. Thus there will no time periods when there is No AC Power to the Load connected to the UPS.
Different Types of Uninterruptible Power Supplies (UPS)
1. Offline UPS or Standby UPS
It is an inexpensive solution for home and small office use that provides basic surge protection and limited battery backup for short power outages.
2. Line Interactive UPS
It is an option for small businesses, as well as a good choice for use with small business security systems and networking equipment.
3. Online Double Conversion (or “True Online”) UPS
It is the best power conditioning option available; eliminates all electrical disturbances; commonly used in “mission-critical” environments such as hospitals or data centres.
Selecting the right UPS will depend on the sensitivity of your connected equipment and the “quality” of your power source.
Final Thoughts
The UPS is a complex device that guarantees clean and stable power supply to all critical applications without interruption. The UPS will protect equipment from spikes, power outages, noise interference, and frequency changes by supplying clean and smooth power. When selecting the best UPS system for your unique environment, you can minimize data loss, increase uptime, and increase your equipment’s life expectancy, no matter what happens with unexpected or unpredictable power conditions.
