Learning the Lingo: Standard IEEE Terminology

Engineers hear and use many terms associated with power-quality issues, but there is often confusion as to the precise meaning of the common words and phrases. Some of the more common ones-brownout, transient, spike, surge and dip-are inaccurate and do not adequately reflect the true duration and magnitude of power-quality disturbances.

01/01/2001


Engineers hear and use many terms associated with power-quality issues, but there is often confusion as to the precise meaning of the common words and phrases. Some of the more common ones-brownout, transient, spike, surge and dip-are inaccurate and do not adequately reflect the true duration and magnitude of power-quality disturbances. The definitions of the terms as used in IEEE 1159 are as follows:

  • Transient. An increase in voltage of up to eight times the nominal voltage level of very short duration, on the order of microseconds.

 

  • Instantaneous voltage sag or swell. A decrease (sag) or increase (swell) in voltage that lasts from 0.5 to 30 cycles with a magnitude of 0.1 to 0.9 times the nominal voltage levels.

 

  • Momentary voltage sag or swell. A decrease or increase in voltage generally having the same magnitudes as the instantaneous events, but with a duration of from 30 cycles to 3 seconds.

 

  • Temporary voltage interruption. A complete loss of voltage lasting from 3 seconds to one minute.

 

  • Sustained undervoltage. A decrease in voltage of between 0.8 and 0.9 times the nominal voltage for a period greater than one minute.

IEEE 1159-1995: Characteristics of Electromagnetic Phenomena


CategoryTypical DurationTypical Magnitude

Transients

Impulsive

nsec. to msec.

na

Oscillatory

3 msec. - 5 usec.

0-8 per unit (pu)

Short-Duration Variations

Instantaneous Sag

0.5-30 cycles

0.1-0.9 pu

Instantaneous Swell

0.5-30 cycles

1.1-1.8 pu

Momentary Interruption

0.5 cycles-3 sec.

less than 0.1 pu

Momentary Sag

30 cycles-3 sec.

0.1-0.9 pu

Momentary Swell

30 cycles-3 sec.

1.1-1.4 pu

Temporary Interruption

3 sec.-1 min.

less than 0.1 pu

Temporary Sag

3 sec.-1 min.

0.1-0.9 pu

Temporary Swell

3 sec.-1 min.

1.1-1.4 pu

Long-Duration Variations

Sustained Interruption

& gt;1 min.

0.0 pu

Undervoltage

& gt;1 min.

0.8-0.9 pu

Overvoltage

& gt;1 min.

1.1-1.2 pu

Voltage Imbalance

steady state

0.5-2%

Waveform Distortion

DC Offset

steady state

0.0-0.1%

Harmonics

steady state

0-20%

Inter-harmonics

steady state

0-2%

Notching

steady state

na

Noise

steady state

0-1%

Voltage Fluctuations

intermittent

0.1-7%

Power Frequency Variations

&10 sec.

na





Product of the Year
Consulting-Specifying Engineer's Product of the Year (POY) contest is the premier award for new products in the HVAC, fire, electrical, and...
40 Under Forty: Get Recognized
Consulting-Specifying Engineer magazine is dedicated to encouraging and recognizing the most talented young individuals...
MEP Giants Program
The MEP Giants program lists the top mechanical, electrical, plumbing, and fire protection engineering firms in the United States.
April 2018
VRFs, lighting controls, BIM coordination, and more
March 2018
Sizing water pipes, ASHRAE 90.1, recovering waste heat, and more
January/February 2018
Sizing water pipes, ASHRAE 90.1, recovering waste heat, and more
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me