El siguiente es un test que he ubicado en la web de Belden y que considero apropiado para quienes se encuentren interesados en temas de cables y comunicaciones, lo transcribo sin traducir para que conserve la terminología que normalmente encontrarán en las hojas de especificaciones de los fabricantes.
Prueben con resolverlo y les publico su solucionario en una siguiente entrada (espero que sea más rápido que los resultados de la tía Chu).
Suerte y que la tarde os sea propicia.
1. The most common conductor material used in electronic cable is:
A. Copper
B. Copper covered steel
C. Aluminum
D. Copper alloy
2. The conductivity of copper is:
A. 18%
B. 45%
C. Approximately 85%
D. 100%
3. The most common type of stranding used in electronic wire & cable products is:
A. Bunch
B. Rope Lay
C. Unilay
D. Unistrand
4. Most Belden conductors are tinned because:
A. It helps prevent oxidation.
B. It reduces conductor cost by 15%.
C. It makes crimp termination easier.
D. It makes the conductor more suited to high frequency applications.
5. Conductors can be made more flexible by:
A. Using a thinner insulation.
B. Increasing the number of strands.
C. Silver coating.
D. Lengthening the length of lay.
6. The most common conductor for fixed applications is:
A. Solid
B. 7 strand
C. 10 strand
D. 16 strand
7. Copper covered steel conductors:
A. Are stronger than copper.
B. Have better conductivity than copper at RF.
C. Are not used in Broadband/CATV cables.
D. Are used only in non-NEC cables.
8. The advantages of a stranded over a solid conductor:
A. Longer flex life.
B. Less costly.
C. Less flexibility.
D. Improved strength.
9. MATCH (2 points)
Flex Life ________
Stranding ________
Lay ________
Flexibility ________
Skin Effect ________
A. The ease with which a conductor can be bent.
B. As the frequency increases, the flow of electrons is limited to the surface of the conductor.
C. A measure of the ability of the conductor to bend repeatedly without breaking.
D. Twisting a group of wires to form a single conductor.
E. The distance required for one strand to complete one revolution about the strand which it is cabled.
10. The primary purpose(s) of the shield is/are:
A. To contain electrical energy.
B. Protection from external interference.
C. Color coding.
D. Both A and B.
11. The shield material chosen is determined by:
A. Required shield effectiveness.
B. Mechanical strength.
C. Cost
D. All of the above.
12. The advantages of the Beldfoil shield are:
A. Low frequency shield effectiveness.
B. Tensile strength.
C. Physical strength.
D. 100% coverage.
13. Belden’s shorting fold:
A. Eliminates the escape of energy through the slot.
B. Is isolated from the drain wire.
C. Degrades shield performance.
D. Eliminates metal to metal contact.
14. The Duofoil shield:
A. Has an extra layer of polyester.
B. Improves shield reliability and effectiveness.
C. Reduces flex life.
D. Is more effective at low frequencies.
15. Braid shields:
A. Can be copper or aluminum.
B. Provide marginal flex life.
C. Are effective at high frequencies.
D. Provide 100% coverage.
16. Braid shields, when compared to foil shields, are:
A. Lighter weight.
B. Easier to terminate.
C. Stronger, mechanically.
D. Lower cost.
17. MATCH (2 points)
Drain Wire _________
Shield _________
Braid _________
Crosstalk _________
Beldfoil _________
A. Contains electrical energy.
B. Mylar and aluminum.
C. Eases termination.
D. Transfer of energy from one cable member to another.
E. One set of strands is applied clockwise, the other counter clockwise.
18. Thermoplastic materials:
A. Include PVC, Polyethylene, and FEP.
B. Will not melt at high temperatures.
C. Are most popular in cable constructions.
D. Both A and C.
E. All of the above.
19. Thermoset materials have advantages that include:
A. Easier to color than thermoplastic materials.
B. Will melt at high temperatures.
C. Excellent low temperature characteristics.
D. Tend to kink and curl.
E. Both A and C.
20. The primary purpose of the jacket is:
A. Protection from the environment.
B. To isolate the conductors, electrically and physically, within a cable.
C. Protection from external interference.
D. Protection from crosstalk.
21. Polyethylene:
A. Excellent moisture resistance.
B. Very good dielectric properties.
C. Used in direct burial.
D. All of the above.
22. PVC:
A. Rarely used for cable insulations.
B. Poor flame and water resistance.
C. Has a variety of formulations.
D. Is difficult to color.
23. Polyurethane is:
A. Used in highly abrasive environments.
B. A thermoset material.
C. Very flame retardant.
D. Used as coaxial cable insulation material.
24. FEP has many outstanding advantages including:
A. Low flame spread.
B. Low cost.
C. High elongation.
D. All of above.
25. Dielectric strength is:
A. The determining factor for capacitance, impedance, and relative performance.
B. The material’s ability to withstand voltage breakdown.
C. The maximum voltage allowed by UL to be applied.
D. The physical breaking strength of the insulation material.
26. Neoprene:
A. Similar to rubber characteristics.
B. Good oil and ozone resistance.
C. Has good aging characteristics.
D. All of the above.
27. Lower dielectric constant means:
A. Low attenuation.
B. Low capacitance.
C. High velocity of propagation.
D. All of the above.
28. Solid insulation is:
A. Most common.
B. Has air voids.
C. Difficult to apply.
D. Used to reduce the dielectric constant.
29. Cellular or foamed insulations are:
A. Most common.
B. Have no air voids.
C. Easy to apply.
D. Used to reduce the dielectric constant.
30. MATCH ( 2 points)
Temperature rating _________
Velocity of propagation _________
Capacitance _________
Tensile strength _________
Attenuation _________
Elongation _________
Dielectric strength _________
A. A measure, expressed in picofarads per foot, of the material’s ability to store electrical energy.
B. A measure, expressed in decibels per 100 feet, of the cable’s loss of electrical energy.
C. The insulation’s ability to contain or withstand voltage without breaking down.
D. The range of temperatures at which a material can be used without degradation.
E. How far an insulation will stretch before it breaks.
F. The amount of force, measured in pounds per square inch, that it takes to break an insulation.
G. Expressed as a percentage, the transmission speed of an electrical signal down a length of a cable compared to its speed in free air, which is also the speed of light.
