UPS Power Quality Management

How Uninterruptible Power Supply (UPS) Devices Impact Power Quality Management

As a back-up power supply, a UPS is able to continue providing power to critical devices during a power cut or break in power. UPS devices provide quality power even when connected to the mains, which is vital to equipment protection.  

Uninterruptible power supply (UPS) explained

The UPS supplies battery backup power through an inverter when the utility power fails or drops below unacceptable voltage levels. This quality power supply will protect hardware such as computers, data centres, telecommunication equipment or other electrical equipment where an unexpected power disruption could cause damage.

Common UPS features

UPS devices are available in different models and sizes, providing quality power to critical devices across industries. Some key features include: v

  • Adjustable output
  • Automatic shutdown initiation
  • Battery monitoring
  • Ground system monitoring
  • Power monitoring
  • Constant voltage output
  • Local controls
  • Data logging
  • Load management
  • Network interface
  • Remote control
  • Security measures

Role of a UPS

The UPS devices rely on batteries to seamlessly take over the critical load if the incoming mains supply fails. In addition, a UPS will also manage the power quality even when the load is being supplied by the utility grid. This is important because, alongside load shedding, the main power supply is susceptible to disturbances that could damage or completely destroy a sensitive load.

Critical applications relying on quality power

There are many industries that rely on critical devices which need high-quality power constantly. Some devices are: 

Consequences of interrupted power supply

Obviously, load shedding will have dire consequences on such critical equipment, leading to outright damage and destruction, but even a halt in supply could have disastrous consequences. These include software crashes and a loss of data, loss of essential transaction information and subsequent public relations’ and communications’ disasters.

Types of power supply issues

Here is a look at some of the power supply interruptions that will be impeded by the implementation of a UPS device:

  • Spikes: a quick voltage transition on the mains waveform which can damage electrical components and corrupt software. These are often caused by equipment switching high electrical currents, but can also be caused by lightning strikes. 
  • Electrical noise: this is a disturbance between the line and earth (common mode noise) or a disturbance between line-to-line and line-to-neutral (normal mode noise). This is caused by lightning strikes, load switching, cable faults or radiofrequency equipment. 
  • Surges: this is an increase in voltage which can degrade a computer’s power supply components causing failure. They happen after a large load is switched off (such as load shedding) or after sub-station load switching. 
  • Sags: this can happen for several cycles and includes a drop in the mains supply voltage, usually because of switching on large loads like air conditioners. They can cause computer re-boots if the sag is too much. 
  • Harmonics: these are caused by non-linear loads which draw peak currents from the mains, often caused by controlled rectifiers, switched-mode power supplies or rotating machines. Equipment affected includes computers, photocopiers and printers with the rise in current, increasing temperatures and causing the equipment to overheat.
  • Brownouts: just like sags, there is a drop in voltage, but brownouts happen for a longer period of time when the mains supply can’t cope with the load demand.
  • Blackouts: this is a complete break in power caused by load shedding, supply line faults, and electrical storms. The damage to equipment can be devastating. 

UPS as a protection device

With the current electricity shortage and constant disturbances experienced by the power grid, implementing a UPS for quality power is essential to protect all critical devices. A UPS with on-line double conversion topology is the best option as it will provide the highest level of power protection. Latest technology UPS units now incorporate input power factor correction technology which reduces harmonics and improves power factor reflected back on to the mains grid resulting in cost savings.   The UPS rectifier & inverter both regulate the battery charging and inverter output parameters, maintaining its level of supply regulation even when it is operating from the UPS battery during a power failure.

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