G&L MMC-A2, Hardware Manual

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CE and EMC Guidelines
158 MMC Hardware Manual G & L Motion Control Inc.
11.3 RFI Emission and Immunity
The EMC product characteristics are classified by the emission and
immunity performance.
Emissions not only include radiated noise from the product enclosure and
cabling, but also that which is conducted away from the product along the
cables connected to it. This may be subsequently radiated from the cable or
conducted directly into another product which shares this cable e.g. the main
AC supply.
Immunity is how susceptible a product is (e.g. to the radiated and conducted
emissions from the product mounted next to it). To ensure compatibility, the
immunity of a product must always exceed the expected emissions in the
environment in which it operates as is shown in the diagram below. This is
to ensure a margin of safety.
Figure 11-1: Safety Margin
In addition to conducted and radiated immunity, products must also be
capable of withstanding:
1. Electrostatic discharges (ESD)
2. Conducted fast transient voltages
The discharge spark generated from ESD can easily damage electronic
components. The conducted fast transient voltages are induced in cables laid
in close proximity to other cables in which large inductive loads are switched
(such as relays, contactors, and AC motor starters). This is a good example
of what can happen to sensitive control and signal cabling connected to
drives when poorly installed in enclosures on industrial sites.
Compatibility Levels
Safety Margin
Immunity Level
Emission Level