Common Power Problem | APC UPS Blog

What are Frequency Variations?

Frequency is a change in the way alternating current (AC) flows. Frequency is closely connected to the speed of the rotation of the motor of a generator. The frequency of power generators in the United States and other countries is 60 Hz and the motors of these generators rotate at 3600 rpm. Variations in frequency can cause the rotation in the motor to change. When this happens, there will be changes in the efficiency of the motors.

Areas connected to a stable power grid do not typically experience frequency variations. Frequency variations normally affect areas using a dedicated power generator. High demand for power worsens the situation. While this common power problem does not affect computer systems, it does have a negative effect on the efficiency of devices dependent on a stable frequency. Similar to voltage fluctuations, frequency variations can also cause lights to flicker.

These frequency variations may make the rotation of the motors faster or slower since they will have to match the frequency of the power input. This will cause the motors to become inefficient. It may also cause the motors to heat up over time and result in the gradual breakdown of the motor. There may be some rare instances when power failure will happen due to frequency variations.

To deal with frequency variations, it is necessary to check all sources of power. After assessing the power sources, it is important to make the necessary repairs or corrections, and, if needed, replace them. It may also be necessary to move sensitive loads to manage this common power problem. The use of an uninterruptible power supply (UPS) system and a power conditioner can reduce the effects of frequency variations.

What are Swells and Overvoltages?

Swells and overvoltages are basically the opposite of sags and undervoltages. A swell is an increase in voltage lasting up to one minute, and an overvoltage is the long-term effect of a swell. These situations happen when available voltage is higher than the demand. It normally starts when there is a huge demand for power. Due to this, utility companies normally increase voltage to meet the demand. When the demand goes down rapidly, there is the possibility that the voltage will remain high causing the swell or overvoltage.

These power problems normally affect rural areas since utility companies usually leave voltage at a high level over the weekend even after the demand has gone down. These situations also happen when the system voltage regulator is inefficient, or when the transformer settings are not set properly by the power company.

Even when overvoltages are brief, they can be damaging to equipment. These power problems can cause equipment to overheat and damage them. They may also cause lights and monitors to flicker. Data centers are susceptible to these situations since they may cause data errors in computer systems. Semiconductors may also be damaged by overvoltages and swells.

To prevent swells and overvoltages from affecting sensitive equipment, it is necessary to use an uninterruptible power supply or UPS system. While the most basic protection against this power problem is a standby UPS system, the best way to protect equipment from a swell or overvoltage is by using an online UPS. These devices protect equipment from sudden increases in voltage. They automatically adjust voltage in case these power problems occur to ensure electricity-powered equipment are protected.

Sources:

http://www.on365.co.uk/Power__and__Cooling/Most_Common_Power_Problems.aspx

http://www.apcmedia.com/salestools/VAVR-5WKLPK/VAVR-5WKLPK_R1_EN.pdf?sdirect=true

https://www.linkedin.com/pulse/6-common-power-problems-ted-ochieng-otieno-cem-?forceNoSplash=true

https://www.tripplite.com/support/articles/articleid/common-power-problems

http://www.acousticfrontiers.com/201348what-are-swells-and-overvoltages/

http://electricity2all.blogspot.com/2013/05/over-voltage-and-voltage-swell.html

What are Interruptions?

One of the seven main types of power problems is an interruption. An interruption is a total loss of power for a specific, short period of time. The power loss can range from a fraction of a second to over two minutes. Interruptions happen when the electric power grid is damaged by weather disturbances, such as lightning strikes and strong winds, among others.

Interruptions are classified according to how long the total power loss lasts. Instantaneous interruptions last for less than a second. Temporary or momentary interruptions can last up to two seconds while interruptions lasting for over two minutes are called sustained interruptions.

While power grids have backup systems to make up for issues leading to power interruptions, there is no such thing as a perfect system. Aside from weather disturbances, interruptions can also be caused by equipment failure. Automatic circuit reclosers can also cause power interruptions. These devices shut off power when the system detects an increase in current due to a short circuit in the system. Cutting off the power protects the whole system from possible damage. The power will be put back on by the recloser after a certain period of time.

Power interruptions can cause data loss, lost revenue and downtime for computer systems. To deal with this power problem, it is necessary to invest on an efficient uninterruptible power supply system as well as a generator. A UPS will allow equipment to continue running even after a complete loss of power is experienced since they provide continuous power supply to the critical equipment. To ensure protection against power interruptions, it is also necessary for the battery of the UPS to be fully functional.

References:

http://www.on365.co.uk/Power__and__Cooling/Most_Common_Power_Problems.aspx

http://www.apcmedia.com/salestools/VAVR-5WKLPK/VAVR-5WKLPK_R1_EN.pdf?sdirect=true

https://www.tripplite.com/support/articles/articleid/common-power-problems