Greenlee DM-500 Manuel D'instructions page 10

Harmonics Function (DM-510 only)
Harmonics are unwanted AC voltages or currents at frequencies that are multiples of the
standard frequency. Usually caused by devices with non-linear load (solid state lighting
ballasts, solenoids, etc.), harmonics can cause voltage disturbances in high-impedance
systems. These voltage harmonics will then affect other devices in the same voltage
distribution system. Harmonics can cause:
• transformers, generators and motors to overheat and burn out
• circuit breakers to trip
• fuses to blow
• neutral lines to overheat
• bus bar and circuit breaker panel vibration
The harmonics function provides a cost-effective method of detecting harmonics. The display
will show a percentage (0% to 100%) that indicates the amount of deviation from a standard
sinewave. A reading of 0% indicates a pure sinewave.
Harmonics Table
Input Waveform
10
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Description
No distortion, pure Sinusoidal,
y = 100sin(ωt)
Fundamental with 10% 3rd harmonics,
y = 100sin(ωt) + 10sin(3ωt+π)
Fundamental with 20% 3rd harmonics,
y = 100sin(ωt) + 20sin(3ωt+π)
Fundamental with 30% 3rd harmonics,
y = 100sin(ωt) + 30sin(3ωt+π)
Fundamental with 40% 3rd harmonics,
y = 100sin(ωt) + 40sin(3ωt+π)
Fundamental with 50% 3rd harmonics,
y = 100sin(ωt) + 50sin(3ωt+π)
HAR Value
0%
4%
8%
13%
17%
19%