The Electric Network


In theory, public and private network distributions supply electrical equipments with a sinusoidal voltage having a fixed amplitude and frequency.

However, under field conditions, various national electrical authorities are only able to guarantee a voltage ranging from -15% to +10% and frequencies from +4% to -6% respect to the nominal value.

In addition, the sine wave voltage is often distorted by various disturbances present in the electrical distribution line or by the user. Disturbances originating from electrical distribution are:

•  Atmospherics
•  Lightning able to cause sudden spikes
•  Broken wires caused by the accumulation of frost
•  Short circuit or interruption caused by falling branches on the lines
•  Casual broken cables caused during excavation or any other building construction activity
•  Electrical distribution breakdown
•  Unbalanced phases
•  Intervention of protection or adjustment devices for load distribution
•  Maintenance

Disturbances caused by user are:

•  Power failures caused by starting of engines
•  Power failures and high-frequency interferences caused by equipment such as arc furnaces, welding machines, ...
•  Harmonic distortions produced by electronic power equipment
•  Current induced by starting up of indoor installations (elevators, hoists, ...)
•  Harmonic disturbances generated by fluorescent lighting systems

Disturbances on the electric distribution can be classified as:

Blackout
Electricity Interruption for more than 10 ms




Dynamic Undervoltage
Undervoltage for less than 16 ms




Dynamic Overvoltage
Voltage increase for less than 16 ms




Undervoltage
Undervoltage for more than 16 ms




Overvoltage
Voltage increase for more than 16 ms




Lightning
Electrical intensity caused by Atmospheric Electrical discharges




Voltage Surge
Sudden voltage increase for less than 4 ms




Frequency Variation
Frequency changes on the voltage supply




Voltage Distortion
Voltage distortion for short periods




Voltage Harmonic
Voltage distortion caused by harmonics present in the mains supply




These disturbances on the electric network are the main cause of damages of electrical and electronic equipments with a possible loss of data due to sudden shutdowns or damages in the memory and storage systems.

To overcome these problems, solutions may be several. The most common is to use an UPS (uninterruptible power supply) for sensitive equipments or a stabilizer for less sensitive equipments.

UPS Technology

According to the standard regulation: IEC 62040-3, UPS are classified and identified as follows:


Easy Interactive (VFD)

The Easy Interactive technology is identified with the initials: VFD (Voltage and Frequency Dependent).
This means that while operating in Mains the UPS output frequency and voltage are dependent on the UPS input frequency and voltage. In fact these UPS are able to protect any connected equipment from small voltage changes by means of filters and from blackouts by means of battery/inverter.




Tecnoware ranges that use Easy Interactive technology are:

•  UPS ECO
•  UPS ECO STRIP


Line Interactive (VI)

The Line Interactive, Technology is identified with the initials: VI (Voltage Independent).
This means that while operating in Mains the UPS output frequency is dependent on the input frequency while the voltage is handled by the UPS. It is in fact through the stabilizer circuit that these UPS are able to protect the connected equipment from persistent voltage disturbances such as overvoltage, and Blackout.



Tecnoware ranges that use Line Interactive technology are:

•  LEONARDO INNOVATIVE POWER SYSTEM
•  UPS ERA LCD
•  UPS EXA


On Line (VFI)

The On Line Technology is identified with the initials: VFI (Voltage and Frequency Independent).
This technology is commonly called “double conversion”. During operations in mains, the UPS output is fed through the rectifier which converts the UPS input voltage from alternated to continuous voltage, in conjunction with the inverter which transforms again the continuous voltage into alternated voltage. This system permits to output voltage to be perfectly sinusoidal, clean and very stable in voltage and frequency, apart from problems present in the mains.




Tecnoware ranges that use Easy Interactive technology are:

•  UPS EVO DSP MM
•  UPS EVO RT
•  UPS EVO DSP RACK MOUNT
•  UPS EVO DSP TM
•  UPS EVO DSP TT


Summary table shows effectiveness of different technologies in relation to electric disturbances present on Network:




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