Power Quality Flashcards
Harmonics do not benefit a power system they what?
Have no useful purpose
Excessive heat caused by harmonics do what for a transformer
Reduce the life of the transformer
10° above the insulation rating will cause 50% reduction in life
A K factor transformer is an index of the transformers ability to carry harmonic currents while operating in the temperature limits.
The higher the K rating the more non linear loads it can handle
Standard transformers aree designed for what load?
Linear loads only
The neutral conductor in a k rated transformer is?
Double the size of a standard transformer
Harmonics are sinusoidal waveforms with frequencies that are integral multiples or the?
Fundamental frequency
While viewing the fundamental 60Hz display and the 5th harmonic 300Hz display the fundamental frequency completes?
1 complete cycle for 60Hz and the 5th harmonic completes 3 cycles within the same duration
Harmonics originate in:
The switch mode of power supplies
Examples:
Electronic ballasts
VFDs
And oven and furnace controls
The K rating on a transformer reflects?
The ability of the transformer to operate properly with certain types of loads
Some problems caused by harmonics are?
Blown fuses
Burn out motors
Tripped breakers
Overheated neutrals
Overheated transformers
Excessive heat
The detrimental (harm) effects on transformers caused by harmonics are? (5 of them)
Increased temperature
Increased neutral current flow
Increased core losses
Increased sound levels
Decreased efficiency
Triple harmonics
Add up of the neutral conductor because they are in phase and cannot cancel each other out
K rated transformers do not eliminate harmonics, they help?
Deal with the added heat caused by electronic equipment
Power quality problems that have multiples of the fundamental frequency of 60Hz are known as
Harmonics
Power quality problems that cause incorrect signals to be sent to the input modules or equipment to behave erratically are referred to as what?
Noise