Appendix B Emc Installation Guidelines; Installation Guidelines Compliant With Emc Regulations; General Introduction; Emc Features - INVT Goodrive3000 Series Operation Manual

Goodrive3000 series medium voltage VFD

Appendix B EMC installation guidelines

B.1 Installation guidelines compliant with EMC regulations
B.1.1 General introduction
EMC is short for electromagnetic compatibility, which refers to the ability of a device or system to function properly in its
electromagnetic environment and not constitute an unbearable electromagnetic disturbance to anything in that
environment. EMC includes two aspects: electromagnetic interference and electromagnetic immunity.
Electromagnetic interference can be divided into two categories according to the transmission paths: conducted
interference and radiation interference.
Conducted interference propagates along any conductor. Therefore, any conductor, such as wire, transmission line,
inductor, and capacitor, is a transmission channel for conducted interference.
Radiated interference is in the form of electromagnetic waves that propagate with energy that is inversely proportional to
the square of the distance.
Electromagnetic interference must have three conditions or three elements at the same time: interference source,
transmission channel, and sensitive receiver, each of which is indispensable. The solution of EMC problem mainly
focuses the three elements. For users, the solution of EMC problem is mainly in transmission channels because the
equipment as interference source or receiver cannot be changed.
Different electric and electronic devices have different EMC capacities because of adopting different EMC standards or
classes.
B.1.2 EMC features
Like other electric or electronic devices, the VFD is not only an electromagnetic interference source but also an
electromagnetic receiver. The operating principle of the VFD determines that it can produce certain electromagnetic
interference noise. And the same time the VFD needs to be designed with certain anti-jamming ability to ensure the
smooth working in certain electromagnetic environment. The following describes its EMC features:
Input current is non-sine wave. The input current includes large amount of high-harmonic waves that can
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cause electromagnetic interference, decrease the grid power factor and increase the line loss.
Output voltage is high frequency PWM wave, which can increase the temperature rise and shorten the life of motor.
And the leakage current will also increase, which can lead to the leakage protection device malfunction and generate
strong electromagnetic interference to influence the reliability of other electric devices.
As the electromagnetic receiver, too strong interference will damage the VFD and influence the normal
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using.
In the system, EMS and EMI of the VFD coexist. Decrease the EMI of the VFD can increase its EMS ability.
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B.1.3 EMC installation guidelines
In order to ensure all electric devices in the same VFD to work smoothly, this section, based on EMC features of the VFD,
introduces general EMC principles in several aspects including noise control, site wiring and grounding for reference in
site installation.
B.1.3.1 Noise control
All the connections to the VFD control terminals must use shielded wires. The shield layer of wire must be grounded near
the VFD entrance. The ground mode is 360-degree loop connection formed by cable clips. It is not allowed to connect the
twisted shield layer to the ground of the VFD, which greatly decreases or loses the shield effect.
The cable (motor cable) for connecting the VFD and the motor adopts a shielded cable or an independent wiring slot. The
shield layer of the motor cable or the metal casing of the wiring slot is connected to the ground of the VFD and the other
end is connected to the motor casing. If the noise filter is installed at the same time, the electromagnetic noise can be
greatly suppressed.
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EMC installation guidelines