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Some UPS Systems can be connected in parallel to achieve redundancy in the system. Usually expressed as n+x, where n is the number of UPS Systems you require to meet your load requirement and x is the number of additional UPS you have above this number. This allows for ‘x’ number of UPS to be removed from the circuit without losing UPS System support.

Redundancy can also be achieved if your load has dual inputs and providing power by two separate UPS Systems. In such circumstances you could remove the need to parallel the UPS together.

Since in this situation, the UPS output are not necessarily in synchronisation it could end up that in a system designed to operate at 230V, there is a two power waveforms in anti-phase registering a 460V potential. This would generally be unacceptable in many environments.

Usually a UPS output frequency is synchronised to the input power frequency. This allows the UPS to “bypass” without any loss of power in the event of a fault or overload. As a result, the AC power source feeding the UPS Systems must originate from the same supply.

When the UPS drop onto battery power during a power outage their outputs are then controlled by their own internal clocks. A full power waveform is generated in 20 milliseconds. In order for two waveforms to be antiphase there needs to be a time delay between them of 10 milliseconds. In a 5 minute power cut this means that two disparate UPS systems need only have a variance between their clocks of around 30ppm or 0.003% – a tiny amount – for an antiphase situation to occur.

There needs to be some sort of communication between the UPS Systems to prevent this situation from occurring. Although many UPS Systems can be connected in parallel, independent synchronisation is not possible. Dale Power Solutions manufacture 6KVA and 10KVA online double conversion UPS Systems that have this very feature – allowing the UPS to be independent but with synchronised output voltage.

Power Inspired offer the full range of Dale UPS Power Systems and other Battery Backup products.

Tony Bell Hardware battery backup, computer hardware, computers, electronics, generators, Hardware, power, power protection, Uninterruptible Power Supplies, UPS, UPS System

Online Double Conversion UPS Systems are so called as they at first take your raw AC power and convert this into DC power. This is the first conversion stage. The inverter then takes DC power and then converts this into AC power. This is the second conversion stage and hence the term “double conversion”.

Other UPS System technologies do not use this method and instead the inverter will only operate when it is switched on. This gives other technologies the benefit of higher efficiency and quieter operation as the inverter does not require forced cooling.

When an offline or line interactive unit switches to battery operation there is a gap during this transition. This can be anywhere from 2 milliseconds if everything is in the UPS’ favour or as high as 20-50 milliseconds if it is not. A normal 50Hz mains power waveform has a cycle length of 20 milliseconds, so the best case we lose 10% of the power momentarily.

An Online UPS System has no such gap. The only change internally is that instead of the DC buss receiving power from the rectifier it receives power from the batteries. This change is undetectable on the output and there is zero transition time.

On other technologies, the mains power goes straight through. The inverter only comes into play when the mains voltage is out of tolerance. This means that there are variances in the output voltage. Even UPS that claim to offer Automatic Voltage Regulation or AVR do have varying output voltages from anywhere from 208 to 253V.

The online UPS output is independent of the input and delivers a newly created power waveform. The output voltage is constant and unchanging and in many cases can also be adjusted to meet your requirements.

Any distorted waveforms or variations in frequency are not blocked by line interactive or offline systems and feed these power problems directly to your load. The newly created power waveform in an online UPS System ensures that your load is provided with high quality power at all times.

In summary an online UPS System recreates a new power waveform that is clean, high quality and free of any power anomalies. This is why online double conversion UPS Systems are considered to be the only solution for critical power.

Power Inspired offer the full range of Dale UPS Systems and other Power Protection products.

Noni Miggus Hardware battery backup, computer hardware, computers, electronics, generators, Hardware, power, power protection, Uninterruptible Power Supplies, UPS, UPS System