UPS systems, as I have mentioned numerous times before, are mandatory in a data center to avoid crashing of servers when there is a power failure. While number of alternatives has been suggested to replace the lead acid batteries with something a little more eco-friendly, we have failed to consider what can be done to improve the efficiency of the existing UPS systems in the data center. After all, not all data center management teams can rush over and replace their outdated UPS systems with newer technology.
Also, as I have mentioned in my previous posts, ultracapacitors are feasible only in certain environments i.e. in areas where the power fails frequently and for very short durations. Ultracapacitors have the ability to charge and discharge very quickly. It is a very expensive option if you want to support the backup power using ultracapacitors even in areas where the power failure lasts for time durations longer than what the capacitor is able to provide backup for.
There are some techniques that you can adopt to improve the efficiency of the UPS system and increase their life span. The efficiency of the battery wanes down due to continuously subjecting the battery to charging and discharging cycles without being allowed to complete both the charge cycle and the discharge cycle completely. There is limited help to prevent the degradation of the UPS systems due to this. However, you can increase the efficiency of the UPS while it is functioning in the following ways:
- By increasing the switching frequency of the UPS
- By keeping the DC voltage required by an equipment closer to the deliverable output of the UPS
- Using high quality wires and converters
Switching frequency is defined as the time taken by a component to go from full on state to full off state. For this purpose, most companies use IGBTs as they have a very high switching frequency and they produce the least disturbance (also called noise) during switching. Noise usually gives rise to problems such as transients and surges. This can be dramatically reduces with the right type of power electronic converters in the UPS system. The input power factor of the IGBT is 0.99. Much of the power is being utilised to charge the batteries.
As for keeping the DC voltage close to the output, this will require you to do an exhaustive analysis of how much power your data center actually requires. You can opt for UPS systems that provide only the required amount of backup as per your requirement. N+1 arrangement is usually preferred in case one of your UPS systems fails. in case you plan to expand your data center in the future, you can always connect modular UPS systems to contain the load. Do not go for a higher voltage capacity UPS system unless it is your only available option.
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