Chapter 7 Review Of Installation Environment; Power Supply Of Inverter (Harmonics And Instantaneous Power Failure); Harmonics - Mitsubishi Electric FATEC FR-A800 Manual

7
REVIEW OF INSTALLATION ENVIRONMENT
CHAPTER 7
7.1 Power supply of inverter (harmonics and instantaneous
power failure)
This section explains the influence of harmonics generated from the inverter on the power supply and
its system to which an inverter is connected. Determine the level of influence on the peripheral
devices according to the amount of harmonics generated from the inverter to consider concrete
countermeasures against harmonics.
This section also explains the influence of voltage fluctuations such as an instantaneous power
failure and voltage drop on the inverter is explained. It is important to understand the operation of the
inverter and motor well.
1. Differences between harmonics and noise
2. Inflow path and the size of harmonic current
3. Harmonic suppression guidelines and handling methods
4. Operation of the inverter and motor at an instantaneous power failure (including an
instantaneous voltage drop)
7.1.1

Harmonics

A harmonic has a frequency that is an integral multiple of the fundamental wave (generally the power
supply frequency). The composition of a single fundamental wave and multiple harmonics is called a
distorted wave. (Refer to Fig. 7.2.)
A distorted wave typically includes harmonics in a high-frequency range (kHz to MHz order).
However, in a power distribution system, harmonics are usually up to 40th to 50th degrees (to 3 kHz).
Harmonics have different problems from those of high-frequency that usually assume an irregular
form. For example, noise and electromagnetic interference from the computer (refer to Section 7.2)
are local problems which are closely related to hard devices, and the influences and measures are
different from those of harmonics in electrical power network. This must be defined first.
i ＝ i
n＝1, 2, 3, ......
f＝Fundamental frequency

7.1 Power supply of inverter (harmonics and instantaneous power failure)

88
REVIEW OF INSTALLATION
ENVIRONMENT
∞
＋ Σ i ・sin （2π fnt ＋ ψ n）
o n
n＝1
· · · · · · · · · · · · · · · · · · · · · · · · · · · · （7.1）