The Importance of UPS in a Data Center

According to common knowledge, UPSs are essential for a data center or mission critical equipment to provide instant backup power. However, UPSs have a significant role in protecting the critical load from all types of mains disturbances. UPS contributes towards the protection of mission critical facilities by safeguarding the data center from incidents like electrical storms and fluctuations in incoming utility power which can distort the AC waveform. If these incidents reach a data center without UPS’s protection, they can not only take the data center system down causing downtime, but also cause corruption and loss, and permanently damage the hardware.

Here, we are covering some mains-born disruptions that a data center can experience, and how UPSs and connected mission critical equipment prevent them from causing damage.

Types of Disturbances in a Data Center

A UPS stands between the data center and various types of mains disturbances. Here are a few common ones:

1. Blackout

The most obvious and common reason for data center managers to invest in a UPS is a blackout. It is the complete power loss when the mains supply fails. In the absence of a UPS, the effects of a blackout can be critical. Blackouts can be caused by various reasons like accidents, supply line fault, thunderstorms, etc.

2. Brownout

The lag in mains supply for long durations. It might arise due to supply incongruence or when the utility mains cannot handle the demand, and the network company has to drop the network voltage. During extreme circumstances, brownouts can last for multiple hours and have serious consequences.

3. Harmonic

The non-linear loads that draw current from main in big peaks. This type of interference can be caused due to rotating machines, switched-mode power supplies, or loads that contain controlled rectifiers. Harmonics cause a disproportionate rise in current and increase in temperatures. Harmonics can lead to issues like equipment overheating, component failure, etc.

4. Electrical noise

This is caused by disturbances between the earth and mains supply line, mostly occurring during lightning strikes, proximity to radiofrequency equipment, load switching, and cable faults. When high-frequency noise is entering the earth, it can affect sensitive electronic circuits, effecting server performance and the corruption of data.

5. Surges

It is the sustained voltage increase over the regular value for more than one supply cycle. It usually happens after a huge load is switched off, or after there is a load switching at the substation. A surge lasting for a longer duration can cause degradation and premature failure.

6. Spikes

These are rapid voltage transitions for a short duration that are superimposed on the AC mains waveform. They can be caused by equipment switching high electrical current, locally grounded lightning strikes, or load switching by power companies. They can damage and destroy electronic and electrical equipment.

7. Sags

It is the power supply drop of several cycles. It is similar to negative electrical spikes but lasts for a longer duration. It occurs due to large load switching or when rotating machinery is started. If sags are deep they can damage computer rebooting.

While some power disruptions can cause certain operations and equipment to fail completely in a few milliseconds, certain other operations can ride harmlessly through several cycles of mains failure.

Choosing a UPS

To protect the data center from the above-mentioned disturbances, it is advisable to go for an on-line UPS rather than off-line UPS. As the off-line UPSs feeds unfiltered, mains power directly to the critical equipment during regular operations, while the on-line category rectifies the mains power even during regular operations. On-line UPSs filter the incoming mains to attain DC battery charging current, and then switch the DC current back to AC to power the critical equipment. An on-line UPS system will ensure the data center equipment will always receive conditioned power and regulated voltage.

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