Ch. 2 - Electromagnetic Compatibility.csv Flashcards Preview

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Flashcards in Ch. 2 - Electromagnetic Compatibility.csv Deck (22):
2

Electromagnetic spectrum includes light, radio waves, microwaves, IR radiation, UV rays, X-rays & gamma rays known collectively as the _________.

electromagnetic spectrum
(2-2)

3

Radiated interference enters electronic devices primarily by means of:

-Proximity to interfering sources
-Missing or inadequate gaskets/enclosures
-Missing or inadequate bonding & grounding system components
-Missing or inadequate device or cable shielding
(not solid state device)
(2-3)

4

ITS designer responsible for EMI? EMC?

Yes - bonding/grounding/shielding
No
(2-4)

5

Internal EMI sources are typically:

-Electrical power supplies
-Rectifiers
-Oscillators
(not electrostatic discharge)
(2-6)

6

How do you measure EMC?

no way to measure
(2-8)

7

EMI is

man made or naturally occurring
(2-16)

8

Natural sources of EMI include

Atmospheric electricity
(2-16)

9

Man made sources of EMI include

generators
(2-16)

10

Three distingushed types of ESD

-Discharge through a spark in the air
-Radiated effects of ESD
-Contact discharge
(2-19)

11

Levels of immunity -

Contact / 2 / 4kV
Contact / 4 / 8kV
Air / 2 / 4kV
(2-20)

12

Q: What is the voltage level in a L2 contact discharge?

4kV
(test)
(2-20)

13

Two types of of unwanted signals on cable in an EMI event:

-Common-mode (CM)
-Differential mode (DM)
(2-28)

14

CM unwanted signals usually ________.

predominate
(2-28)

15

To successfully filter both types of unwanted signal, a ____________ is preferred.

magnetic scheme
(2-28)

16

For DM unwanted signal mitigation, individual _______ can be installed

ferrite beads
(2-28)

17

CM unwanted signal on cabling can

lock up computer
(2-28)

18

DM noise affects equipment by

corrupting transmitted signals on a balanced circuit
(2-29)

19

For branch circuits of 5 kVA or less ____________ should be necessary.

no seperation
(2-44)

20

Table 2.6 VERY VERY IMPORTANT - Min seperation distances:
-Unshielded power lines or electrical equipment close to open or nonmetal pathways
-Unshielded power lines or electrical equipment close to grounded metal conduit pathway
-Power lines enlcosed in a grounded metal conduit in proximity to a grounded metal conduit pathway
-Electrical motors & transformers

-24"
-12"
-6"
47" or 48"
(test)
(2-44)

21

A min. common-mode rejection ratio (CMRR) of _____ is desirable for high-quality chokes over the operating frequency range of interest.

40dB
(2-49)

22

Three major components of the electromagnetically induced interference problem

-Induced electronmagnetic fields from the electrical power system
-Coupling between the electrical power & telecom system
-Susceptibilty of the telecom system
(not unbalanced DM field)
(2-51)

23

The coupling from mutual capacitance and/or mutual inductance between the electrical power & telephone/telecom facility is a function of the:

-Physical separation between the electrical power & telecom facilities
-Length of exposure or cables running parallel throughout their pathways
-Impedance of the return path for the unbalanced current
-Shielding effectiveness of the electrical power &