Can Simulation determine this Power Generation problem?
Can Simulation determine this Power Generation problem?
(OP)
Hi all,
Before I begin, I am new to this forum so if I am conveying my question incorrectly, please bear with me. I have been trying to acquire Solidworks Simulation for the past 3 months (I'm still awaiting my purchasing department), and I only have another 3 months left in my rotation assignment, so any knowledge I can obtain to help me get started the moment I get the program would help tremendously.
I am trying determining the change in resistivity due to a bad electrical connection [the interface of the connector is improperly crimped] on a cable joint.
======[]----------------[]======
^ ^ ^ ^ ^
1 2 3 4 5
1= Cable 1
2= crimped connector 1
3= yoke
4= crimped connector 2
5= cable 2
Given:
What I know is the power generated [I^2*R] by the conductors inside of both cable 1 and cable 2, as well as the surface temperatures of everything. Knowing the material of the cable, I've been able to determine the temperature of the cable conductor [by setting the total Q from heat transfer (conduction convection and radiation) to the environment equal to the power generated from I^2*R losses] I also know that the bad crimp had caused a severe increase in temperature in both connectors and yoke.
What I don't know is the power generation, resistance, or temperature of the connector conductor [its 13kV, everything is insulated]. My question is: knowing the current, can Simulation be able to determine the power generation despite not knowing the resistance? Normally it would all be the same as generated in the cable, but it is altered in this case due to the increased resistance associated with the connection. From what I know, (sorry, I'm Mech E, not EE) I'd need one to determine the other. If I put them back into the heat transfer eq from above, I'll have three unknowns, the third being the temp of the connector, so that still won't help. Do any of you know if simulation would be able to find a way around this? If so, do you know how?
Before I begin, I am new to this forum so if I am conveying my question incorrectly, please bear with me. I have been trying to acquire Solidworks Simulation for the past 3 months (I'm still awaiting my purchasing department), and I only have another 3 months left in my rotation assignment, so any knowledge I can obtain to help me get started the moment I get the program would help tremendously.
I am trying determining the change in resistivity due to a bad electrical connection [the interface of the connector is improperly crimped] on a cable joint.
======[]----------------[]======
^ ^ ^ ^ ^
1 2 3 4 5
1= Cable 1
2= crimped connector 1
3= yoke
4= crimped connector 2
5= cable 2
Given:
What I know is the power generated [I^2*R] by the conductors inside of both cable 1 and cable 2, as well as the surface temperatures of everything. Knowing the material of the cable, I've been able to determine the temperature of the cable conductor [by setting the total Q from heat transfer (conduction convection and radiation) to the environment equal to the power generated from I^2*R losses] I also know that the bad crimp had caused a severe increase in temperature in both connectors and yoke.
What I don't know is the power generation, resistance, or temperature of the connector conductor [its 13kV, everything is insulated]. My question is: knowing the current, can Simulation be able to determine the power generation despite not knowing the resistance? Normally it would all be the same as generated in the cable, but it is altered in this case due to the increased resistance associated with the connection. From what I know, (sorry, I'm Mech E, not EE) I'd need one to determine the other. If I put them back into the heat transfer eq from above, I'll have three unknowns, the third being the temp of the connector, so that still won't help. Do any of you know if simulation would be able to find a way around this? If so, do you know how?






RE: Can Simulation determine this Power Generation problem?
Even if the software package does turn up you would still need to check your model using the hand calcs.
However I would have thought that a voltmeter would be the obvious solution.
Cheers
Greg Locock
I rarely exceed 1.79 x 10^12 furlongs per fortnight
RE: Can Simulation determine this Power Generation problem?
My question really is what does simulation need to determine a power generation? If it can be solved with the given I have, I can work it backwards to get the resistance and use that as a reference for the department when they can finally put a voltmeter on it.
RE: Can Simulation determine this Power Generation problem?
Cheers
Greg Locock
I rarely exceed 1.79 x 10^12 furlongs per fortnight
RE: Can Simulation determine this Power Generation problem?
This is what my plan is going to be:
I know power generated for the cable so that will be constant, but I will vary power generated for the connectors until I get the right surface T, and that will have the correct associated delta T and resistance will be found from the number I used for power generation.
RE: Can Simulation determine this Power Generation problem?
At 13kv I don't think a voltmeter is a good idea, at least not the kind you are probably thinking of.
Zorched
If a bad crimp leaves an open connection at this kind of voltage it doesn't matter. The current will jump the gap and plasma will form which tends to be really hot.
Electricians use non-contact thermal probes to find bad connections all the time. That is what he is after. The rubber insulation is good at insulating electricity and heat.
Considering the cable assembly the energy released by each item's contribution is I^2 * (R1 + R2 + R3 + R4 + R5) using the nomeclature above. However, R1 and R5 dissipate this energy over a large area whereas R2 and R3 dissipate their contribution over a small area. You can use an analogy to electrical conduction for removing the heat from the conductor and connectors where Qheat = I^2R, R is the thermal resistance of a section of insulation and Temp = Voltage.
I would assume the width of insulation carrying heat away from a bad connection to be fixed in size. Because the thermal resistance of the jacket over the wire is considerably smaller than that over the connections you should be able to get a solution fairly easily.
You can guess the width of insulation over a bad connection by perhaps looking at failed or burned connections.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Can Simulation determine this Power Generation problem?
"They are equal, but you cant determine power radiated or convected to the environment off surface Temperature alone."
Yes you can if it natural convection and black body radiation.
Cheers
Greg Locock
I rarely exceed 1.79 x 10^12 furlongs per fortnight
RE: Can Simulation determine this Power Generation problem?
Sorry if I assumed you were thinking of an OTS Radio Shack DVM. Yes, it involves special equipment. Just removing the insulation at 13kv can change things like allow for corona to form.
Allyl is thinking in terms of transient heat transfer. I would think this is steady state so it is a matter of conduction, not absorbtion of energy.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."