# What is Cable: Definition and 628 Discussions

A cable layer or cable ship is a deep-sea vessel designed and used to lay underwater cables for telecommunications, electric power transmission, military, or other purposes. Cable ships are distinguished by large cable sheaves for guiding cable over bow or stern or both. Bow sheaves, some very large, were characteristic of all cable ships in the past, but newer ships are tending toward having stern sheaves only, as seen in the photo of CS Cable Innovator at the Port of Astoria on this page. The names of cable ships are often preceded by "C.S." as in CS Long Lines.The first transatlantic telegraph cable was laid by cable layers in 1857–58. It briefly enabled telecommunication between Europe and North America before misuse resulted in failure of the line. In 1866 the SS Great Eastern successfully laid two transatlantic cables, securing future communication between the continents.

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1. ### Find the Tension in the cable when the lift is moving at constant speed

aaaah just realized the solution after typing here... ... at constant speed, ##a=0##, therefore ##T-mg = 0## ##T=(1050 × 10) =10, 500## Newtons or any insight...welcome. Maybe i should ask...when the lift is moving downwards and there is deceleration then would the Tension be treated in...
2. ### Electrical Creating a Custom Cable: 7-Pin Amphenol Connector and Unique Electrode Input

This cable costs \$200 so I want to build one. I know where to get the round silver plug at right which is a 7 pin Amphenol and I know the pin designations inside. I'd like to know if the left white electrode input socket can be found anywhere or it can only be made special at factory. Have you...
3. ### Calculating Cable Turns for a Job

Hello, I'm trying to help my kiddo with some math, and unfortunately this is stumping me. A full reel of cable has a diameter of 60 inches. A job requires 314 feet of cable. How many turns of cable should be taken off the the reel? The answer is 20 turns, but I can't seem to figure out how...
4. ### Name of the connector used for coax for internet, cable TV, TV antenna

This is embarrassing, All these yrs., I never use one for any design. I just want to make sure it is F type. I am talking just common tv antenna connector. I need to buy the crimping tool and everything, I cannot afford to make mistake. I searched, it should be F-type, just want to confirm...
5. G

### Power dissipated by a resistor on a coaxial cable

I need help with part c. My solution: Is there an other way to do this other than dimensional analysis? P.S "dr an infinitesimal radius", it ofcourse should be dz.
6. ### Can I run cable tv signal and on air tv signal in a single coax?

Hi I currently subscribe to Directv, the signal is from the dish and split into 4 coax to go to 4 different rooms. So each room has a coax output on the wall to hook up to the Directv receiver box. I decided to change to Dish Network. At the same time, I want to install a VHF/UHF digital tv...
7. ### Speed of Current in a coaxial cable

I've found the inductance and capacitance per unit length in a long coaxial cable. I even clearly see that if I multiply the two, I can get the speed of light. How do I begin to find the current wave and its speed though?
8. ### Finding linear acceleration of a spool and cable

My angular acceleration is wrong but all I had done was torque which was 110 NM / I = 930 kg-m^2 and calculated 0.118 rad/s^2. But because this is wrong I am stuck and I have no idea how to find angular velocity to plug into the equation to find linear acceleration.
9. ### Parasitic Inductance, rough estimate -Single cable through steel

DC case - but customer ran their cable run through a couple boxes, this would not be allowed in AC due to the eddy current created in fittings and the enclosure steel. ( I do not even know if code would allow this for DC) - but anyway. This is part of a high power dc system and I suspect the...
10. ### Engineering Drawing FBD: Cable Passes Over a Smooth Peg

Attempting to draw the FBD for this problem but was wondering what to do about the cable, especially when I determine the internal loadings at E. At C, do I only draw one force arrow (CB), or draw both on the left and right side?
11. ### Is this really a 75 Ohm cable?

There have been a few times in my career as a SW engineer when I have gone to the EE's on the project and they have been unable to answer my EE question. My thought is that if I post these problems on this message board, they might make it into the EE curriculum much to the advantage of newly...
12. ### I Pulling cable through underground ductwork.

Hello all, I am an Engineering dropout turned Cable Splicer. In my job we do a lot of Heavy Duty underground cable pulling. Usually plastic jacketed cable through some type of ductwork (typically plastic as well). We use a winch truck and a heavy rope to pull this cable through the ducts...
13. ### Connecting a new cable - different wire gauge

Hi. (not a native English speaker, so apologies in advance for inadequate techical terms) 220V AC, Europe. There is a cable with 5 wires (2.5mm2 crosssection each) that I would like to cut and make a junction box in the attic to connect another cable to it, to get another outlet. The wires are...
14. ### I Derivation of the magnetic flux in coaxial cable

The magnetic flux ##\phi_m = \int{BdA}## The magnetic field of the coaxial cable B = ##\frac{I_{enc} \mu_0}{2\pi r}## since surface area of a cylinder = ##2\pi rdr L, dA = 2\pi L dr## where L is the length of the coaxial cable so ##\phi_m = \int{\frac{I_{enc} \mu_0}{2\pi r}2\pi L dr}##?
15. ### Conducting cable surrounded by two cylindrical shells

What I have done: (a) If we start at ##R_5## then we have ##\Delta V=-\int_{R_5}^{R_1}\vec{E}\cdot d\vec{l}=-(\int_{R_5}^{R_4}\vec{0}\cdot d\vec{l}+\int_{R_4}^{R_3}\frac{\lambda}{\varepsilon_0}dl+\int_{R_3}^{R_2}\vec{0}\cdot d\vec{l}+\int_{R_2}^{R_1}\frac{\lambda}{\varepsilon_0}dl=-\lambda(...
16. ### Modelling of tranformer and MV cable for harmonic studies

For my research project, modelling is needed for dyn5 630 kVA transformer and 20 kV cable NA2XS(F)2Y to do harmonic analysis. For that i need leakage reactance, and resistance of copper losses for transformer. And following parameters for 20 kV cable are also needed. Positive, negative and...
17. ### Why would disconnecting the positive cable first on car battery cause sparks?

When I was 18 years old, I worked at an automobile repair shop doing oil changes and other light mechanical work. The automobile repair shop hired me for this work to free up their real auto mechanics to do more advanced automobile repair work. One time I was assigned the task of replacing a...
18. ### Optimal Solution for Avoiding Cable Slip from Groove

This is a theoretical question where we should explain and show with formulas which option is the best solution for avoiding cable to slip from groove. I believe that since the cable center is closer to the rotation axis (left fairlead), the force on the cable will move the fairlead as well (as...
19. ### Is the cable inside a socket outlet / power strip attached firmly?

I have a power strip that has fallen from height accidentally for a couple of times, there is no observable crack or damage, however, could this lead to bad contacts or anything bad to the electrical/electronic appliance? I'm thinking if the power cable inside is usually well attached
20. ### Cable color standards in the US

I am from Europe and mainly do engineering here but now I have a new project for a machine that is going to be installed on a wind-farm outside of New York. We have a very specific customer spec that specifies the wire colors that we have to use in all the power cables. The spec says the...
21. ### What causes variations in delay in coax cable of the same length?

Hey all, I was doing some tests in lab when I noticed that between two 4.5m RG174 SMA cables, there was a 1ns difference in delay at 4MHz between the two cables. To clarify, theory says 4.5m of RG174 (66% velocity factor) at 4 MHz should have a delay of 22.7ns. I measured one cable at 22ns and...
22. ### I Drawbridge falling before caught by rope/cable - Max force

Hi, I'm currently looking into the forces exerted on a cable if the cable was to go from slack to taut due to a falling object that is pivoted about a lower hinge - such as a drawbridge but instead of slowly lowering, there is slack in the cable causing the bridge to freely rotate about the...
23. ### Sanity check please -- Load cable swinging outward on a rotating crane

So I know Fcp=-m*w^2*r So from the equation -m*w^2*r=m*g*tan(theta) r = r1+r2 so to rewrite -m*(w^2)*(r1+r2)=m*g*tan(theta) So r1+r2=(m*g*tan(theta))/-m*(w^2) r1=((m*g*tan(theta))/-m*(w^2)) - r2 Am I doing this nearly correct?
24. ### Voltage detection in electrical cables

Hello guys! I am a student who currently works on a project based on electrical detection and voltage measurement in electrical cables remotly. So in order to accomplish my work, I'm seeki ng for new ways to detect voltage. I already have some ideas such as using magnetic fields or measuring...
25. ### Finding the tension of a support cable to balance the beam

I know the answer is 170 but I am not sure how to get there. I tried doing things backwards g=9.8 t = fr = mgr 0= 170 + tbl - tbr - 5x9.8x1.5 0= 170 + tbl - tbr - 73.5 -96.5 = tbl - tbr -96.5 = 18*9.8 * 0.2 - 18*9.8*1.4 -96.5 does not equal -211.68
26. ### Work Done by Elevator Cable in Sample Problem 7-6

As stated, part (a) says that the work done by the gravitational force ##\vec{F_g}## is 59 kJ. If ##W_T## is the work done by the elevator cable during the 12 m fall, then using the work-kinetic energy theorem, \begin{align*} K_f -K_i &= W_g + W_T\\ \frac12m({v_f}^2 - {v_i}^2) &= 59000 + W_T\\...
27. ### Magnetic energy inside a coaxial cable

Hi, I have to find the magnetic energy inside a coaxial cable of inner radius ##a## and outer radium ##b##, ##I = I## By using Ampere's law if ##r<a## ##B = \frac{\mu_0Ir}{2\pi a^2}## if ##a<r<b## ##B = \frac{\mu_0I}{2\pi r}## if ##r>b## ##B = 0## Then, the energy in a magnetic field ##E_b...
28. ### Max tip speed of a spinning cable

A company called SpinLaunch claims it can get something to 2200 m/s by spinning it up on a carbon fiber composite arm. I'm trying to figure out the limit of that approach. How fast can you go with existing materials? I tried to work it out for a constant with cable with no payload (result...
29. ### Finding the torque required for telescopic cable mechanism

Summary:: I am designing a linear telescopic system that gets elevated with a step motor, but in order to find the compatible motor, I need to work out the torque that is required for the elevation. I have uploaded my CAD model to this thread with how cables are connected. Could someone please...
30. ### Resistance calculation -- Comparing coax cable insulator resistances

Since both cylinders have the same material, this implies the density is the same. Length is also the same based on the question. We only need to compare the radii for resistance. R2 = pi ((2b)^2 - (2a)^2) R1 = pi (b^2 - a^2) R2/R1 = 4, so my answer is C. But, the given answer is A. Where did I...
31. ### Boost Your Cable TV Signal with Our Reliable Cable Boosters

My cable at ground floor has ok signal but in the second floor with about 20 meters additional cable. It has poor signal lately (because due to more resistance from old wiring). What kind of cable booster can actually boost the signal and can even eliminate the noise, rather than just boxes with...
32. ### Coaxial cable - capacitance, leakage current and power lost

Could somebody check my solution?
33. ### Moments Question (ENGAA 2019) -- Cable and Winch Lifting a Drawbridge

The correct answer is 'B'. I would like some clarification, in regard to the forces that exist in this moments problem. General Queries: 1) Is there friction acting on the hinge in a downward direction (parallel to the wall)? Does the ramp being "smoothly hinged" to the wall mean there is no...
34. ### Maximum tension in a cable holding a drawbridge

My result for this problem is correct, but I would like to submit to you the method I used since it doesn't convince me. The problem asks for the maximum tension on the cable from the transition to 0 to 90 degrees; I firstly concluded just by thinking, not using formulas or particularly formal...

36. ### Ferrite Cores on the output cable of a VFD

Some Variable Frequency Drive manufacturers (such as Allen Bradley) supply a toroidal Ferrite core to wrap the outgoing cables around to reduce EMF. My question is, if a company doesn't supply a ferrite core, how do I work out if one is needed, and how do I correctly size it? I understand that...
37. ### Understanding the deflection of a cable under tension with a force applied in the middle

With the above in mind, I have a cable of E=60GPa, cross sectional area 7e-4m^2. I want to understand the relationship between the tension applied resisting the deflection of the cable when a force is applied so that the cable will not deflect more than 0.7m in this case. Take the force as...
38. ### Determine the magnetic field inside and outside the cable using Ampere's law

My attempt: I realized after i had tried to solve the problem that the current must be constant in the cables. But no information about where the cables has radius a and b is given so how would I go about to find an expression for the current? Thanks in advance!
39. ### Drum and Cable Problem - Formula and Workings

Hi everyone, please could someone assist in the formula for the above A, B, C, D, E and F in order for me to try and resolve the maths questions, I'm just a little stuck on the formula, Thanks in advance all :-)
40. ### Surface Charges on a Coaxial Cable

To find ##\sigma_b## I can use a Gaussian surface of a cylinder of length ##L## and radius ##c>r>b##. Since that is inside of the outer conductor, I know the electric field is zero, so I have from Gauss' Law, $$0=2 \pi L\left(b\sigma_b+a\sigma\right)$$ and easily solve for ##\sigma_b##. For...
41. ### Poynting vector -- Calculate the EM power transmitted down a coax cable

I don't know which part gets wrong
42. ### Magnetic field intensity, flux density and magnetization of coax cable

Inner conductor radius = 1cm outer conductor radius = 10cm region between conductors has conductivity = 0 & 𝜇r = 100 𝜇r = 1 for inner and outer conductor Io = 1A(-az) 𝑱(𝑟) = (10^4)(𝑒^-(r/a)^2)(az) Problem has cylindrical symmetry, use cylindrical coordinate system. Find the total current...
43. ### Characteristic Impedance of a coaxial cable

Image 1: Image 2: I am attempting to learn about transmission lines and am having problems with this homework problem. For part a, I have derived an equation for the maximum electric field within the dielectric. I came up with: with r being the radius and the electric field decreasing with...
44. ### Cable modem+router recommendation needed

I am about to sign up for Comcast/Xfinity internet service for the next 6 months. I have the slowest 25 Mbps speed. I'm not a gamer. Just WIFI for PF and other surfing plus one cable connection to my TV. For the previous 6 months, we got along fine using the WIFI hotspot from my phone...
45. ### Electric energy density in the dielectric of a coaxial cable

V(ρ) = V_o*ln(ρ/0.0018)/ln(45/180) (Attached picture is where the unit vector of r is really ρ.) In cylindrical coordinates ∇V = ρ*dV/dρ + 0 + 0 ∇V =derivative[V_o*ln(ρ/0.0018)/1.386]dρ ∇V = V_o*0.0018/(1.386*ρ) E = V_o*0.0012987/ρ Work = 0.5∫∫∫εE•E dv Bounds: 0.0018 to 0.00045 m D = εE =...
46. ### Electronics Can I pull a network cable from the middle of the run?

I need to run about 70 ft of ethernet cable through my basement, which is actually two separate unconnected spaces ( there is a small gap above the dividing wall). Because of the layout -- bends and very limited space -- it will be much easier to start near the middle and pull toward each end...
47. ### Force of a 220kV Cable falling

Summary: How would you calculate the force at a point of a falling 220kV Conductor? Hi, bit a of a funny one. I need to calculate the force of a cable falling at a point (left edge of a scaffold) as detailed in the attached sketch. (Not to scale what so ever). We’re building a scaffold between...
48. ### Getting cable TV on my laptop - i.e. sans Internet?

Long story short: Sister has dial-up internet* on laptop, can't stream movies. Wants receive network cable to her laptop (wired or wireless) so she can watch movies outside without dragging the TV along. (I know it was once possible to buy a video card to slot into a desktop box that would do...
49. ### Power being transported down the cable

Relevant equation: Since the potential difference V is independent of time and current I is steady, both the electric field and magnetic field are independent of time. Hence, the first term of R.H.S. of (8.9) is 0. If V >0, then ## V_{in} - V_{out} ## = V, ## \Rightarrow...
50. ### Where is the tension applied in a 3 dimensional cable?

Hello, I need to transmit motion between a servo motor and a pulley through a cable. In order to do that, I've screwed a pulley to the servo and fix the cable on both the motor pulley and the pulley. I am working in a scale where the radius of the cable cannot be neglected due to a precision...