CIRCUTOR AFQ Series - Manual (Page 33)

AFQ-4W
Instruction Manual 33
4. OPERATION
4.1.- OPERATING PRINCIPLE
4.1.1.- HARMONICS
Non-linear loads such as: rectifiers, inverters, speed drives, ovens, etc, absorb
periodic non sine-wave currents from the mains.
These currents are composed of a fundamental frequency component, rated at
50 or 60 Hz, plus a series of overlapping currents, with frequencies that are
multiples of the fundamental frequency; they are defined as HARMONICS.
Figure 30: Distorted wave shape decomposition.
The result is a deformation of the current and, as a result, of the voltage, causing
a series of associated side effects. These can be machinery overload, electric
cable heating, circuit breaker disconnection, damage to sensitive units, etc.
Order (n)
Mains frequency
Fundamental: 50 Hz Fundamental: 60 Hz
3 150 Hz 180 Hz
5 250 Hz 300 Hz
7 350 Hz 420 Hz
Table 4: Frequency of each harmonic.
4.1.2.- BASIC CONCEPTS
It is best to define some terms related to harmonics, fundamental for interpreting
any measurement and study:
 Fundamental frequency (f
1
): Original wave frequency (50/60 Hz).
 Order of a harmonic (n): A whole number given by the ratio between the
frequency of a harmonic and the fundamental frequency. The order
determines the frequency of the harmonic (E.g.:
5th harmonic → 5•50 Hz =
250 Hz).