How UPS systems work for critical power supplies?
This article discusses the operation of Uninterruptible Power Supply (UPS) systems for critical power supplies, contrasting theoretical and practical aspects. UPS systems provide instantaneous backup power using lead acid batteries or Rotary Fly Wheel technology. They deliver power for a duration ranging from 1 to 15 minutes during outages, with True Online systems offering uninterrupted power and Line Interactive models providing a micro break in power. Key applications include IT loads, data centers, hospitals, and banks. The article emphasizes the importance of synchronization with Automatic Voltage Regulators (AVRs) and the need for maintenance of both UPS and backup generators to ensure reliability and frequency stability.
In this article we will discuss how UPS systems work for critical power supplies in theory versus reality. UPS systems work as an instantaneous emergency backup. Electrical power source usually consisting of lead acid batteries. For larger systems it can be a Rotary Fly Wheel UPS system. Supporting power electronics converts incoming AC to DC output current. Above all supporting critical power load.
UPS systems provide instantaneous No BREAK power to the downstream load from 1 minute up to 15 minutes during which its stored electrical power will be provided until the GRID power is reinstitute. In True Online double conversion UPS, the electrical power is released from the batteries.Whereas a Rotary Fly Wheel system stores its energy kinetically within the flywheel. Both of these UPS systems are used for critical power supplies. For NON critical loads it is common to use cheap line interactive UPS that ‘spring to life in micro seconds’ when the UPS sees no GRID power. All Line interactive UPS do have a micro break in power before providing the stored power, hence this is ‘break before make’ power and never used for critical power supplies. IT loads, Data Centres, Hospitals, Banks all use UPS systems that are either Double Conversion Uninterruptible power supply (UPS) systems or Rotary Fly Wheel Systems.
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How UPS systems work in reality?
A UPS means a source of interrupted power supply. In the case of power outage, the UPS allows some devices to keep running for a period of time giving you time to back up your files. In the event of a power outage or power drop the UPS will release its stored electrical power to the load and provide the missing power. All UPS systems synchronise the output frequency with the input by means of built in Automatic voltage regulators (AVRs), although we must state that ALL the low cost line interactive UPS don’t have the same robust provisions as the more expensive True Online or Fly Wheel systems. So, having a UPS plays to your advantage as it gives you the assurance that you will be protected in case of power interruption. The UPS also refines the quality of the power as it reaches you building, office and equipment and it turns dirty load into clean load.
If you want real NO Break power protection then don’t install a line interactive UPS
Ensuring your load has both Uninterruptible power and continuous power, any UPS must be backed by a generator. ( Genset) Every Generator also has an automatic voltage regulator (AVR) to keep the output power at 50hz. Should the power fluctuate, it is the AVR that keeps the output power between 49.5 and 50hz. This range of 49.5hz to 50hz needs to be maintained to ensure your load doesn’t lose power even if your emergency power system is still providing electrical power. Frequency is important.An automatic voltage regulator (AVR) keeps the output power frequency at 50hz and no lower than 49.5 hz.Should the frequency drop out of this range, your emergency power from the UPS and Generator will drop the load thus loose power. Replace batteries BEFORE they fail.
Keep your generator fuelled.
Ensure regular service & maintenance regimes are in place for both your Uninterruptible power supply (UPS) systems and backup generators to prevent loss of frequency/power.
For design, equipment and installation of uninterruptible power. Here’s another article to consider UPS Power Systems Failure & How To Prevent Them.
