30 Questions
Which power quality disturbance is defined as a sudden drop in the normal voltage level often resulting in serious equipment malfunctions?
Sag / Undervoltage
What is the defined period of time where the input voltage exceeds the maximum specification that the unit must survive and during which it may need to operate?
Power Surge
What is the increase in AC voltage for a duration of 0.5 cycles to 1 minute's time called?
Overvoltage or Swells
What are very high voltage 'spikes' called?
Transients
What is a steady lower voltage state called?
Brownouts or Under-voltage
Which power quality disturbance refers to a complete loss of power that can last from a few seconds to a few days?
Power failure / Blackout
What causes serious equipment malfunctions and is usually caused by faults on the transmission or distribution network, connection of heavy loads or start-up of large motors?
Sag / Undervoltage
During peak electrical demand, what can utilities do to limit maximum power, causing systems to experience glitches, data loss, and equipment failure?
Brownouts or Under-voltage
What refers to a decrease in the normal voltage level often resulting in serious equipment malfunctions?
Sag / Undervoltage
What is defined as a very high voltage 'spike'?
Transients
What is the height of a standard server rack in inches?
1.75U
What is the formula to calculate the required UPS for the load in Watts with 40% headroom for growth?
$ ext{Required UPS} = ext{Total Wattage} imes 1.4$
When calculating the current load of a rack, what should be added up for each device?
Wattage of each device
What is the height, in inches, of a common rackmount UPS?
1U
Why might you need multiple UPS sometimes?
To avoid a single point of failure
What does calculating the current load of a rack assist the electrical personnel with?
Sizing power delivery method
What is the formula to calculate power (watts) when the amps are given?
$ ext{Power (Watts)} = ext{Voltage} imes ext{Current (Amps)}$
What should be considered when selecting the best UPS for your needs?
The power problems you’re trying to avoid
What is the height, in U, of a rack that takes up 14U of vertical rack space?
14U
What is the form factor related to when selecting the best UPS for your needs?
The physical size and shape of the UPS
Which type of power quality disturbance is caused by voltage or current superimposed on the power system waveform?
Transients
What type of UPS is suitable for devices with high power supply requirements, such as data centers?
Online UPS
What is the recommended growth factor to multiply the total wattage of connected devices to calculate UPS capacity?
$1.40$
Which type of UPS offers surge protection and battery backup, suitable for low power devices like personal computers?
Standby UPS
What type of power quality disturbance can lead to equipment problems like data errors and equipment malfunction?
Noise
In which settings is the rackmount UPS suitable for?
Data centers
What type of UPS provides conditioned power and battery backup, suitable for home and office applications?
Line-interactive UPS
What kind of UPS is required for larger power consumers like data centers?
Three-phase UPS
What is the result of interruptions caused by electrical supply grid damage, lightning strikes, equipment failure, or circuit breaker tripping?
Instantaneous, momentary, temporary, or sustained interruptions
Which type of UPS provides emergency power backup and protection for devices?
Uninterruptible Power Supply (UPS)
Study Notes
Power Quality Disturbances and Uninterruptible Power Supplies
- Transients are a damaging type of power quality disturbance caused by voltage or current superimposed on the power system waveform.
- Noise can be generated by various devices, such as power electronics, control circuits, and radio transmitters, and can lead to equipment problems like data errors and equipment malfunction.
- Interruptions, categorized as instantaneous, momentary, temporary, or sustained, result from electrical supply grid damage, lightning strikes, equipment failure, or circuit breaker tripping.
- An uninterruptible power supply (UPS) provides emergency power backup and protection for devices, with three main types: standby, line-interactive, and online.
- Standby UPS offers basic features, surge protection, and battery backup, suitable for low power devices like personal computers.
- Line-interactive UPS, with better power supply quality and a bypass mode, is suitable for home and office applications, providing conditioned power and battery backup.
- Online UPS provides continuous, high-quality power supply regardless of input utility power condition, making it suitable for devices with high power supply requirements, such as data centers.
- Three-phase UPS is required for larger power consumers like data centers, while single-phase UPS is used for smaller consumers.
- To calculate UPS capacity, add up the wattage of connected devices, multiply by 1.40 for a 40% growth factor, and ensure the load does not exceed 75%-80% of the UPS capacity.
- UPS form factors include desktop/compact UPS, tower/mini-tower UPS, and rackmount UPS, each suitable for different settings and space conservation.
Test your knowledge of power quality disturbances and uninterruptible power supplies with this quiz. Learn about the types of disturbances, such as transients, noise, and interruptions, and explore the different types of UPS systems, including standby, line-interactive, and online. Delve into UPS capacity calculations, form factors, and their suitability for various applications.
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