R,X, & C for 1/C vs 3/C MV Cables

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davechow Active Contributor Join Date: Dec 2013 Posts: 10	R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 10:26 AM
	I have R,X, & C values for 1/C MV 500MCM cable. -For 3/C MV 500MCM cable, Should the R,X, and C values be similar to these of 1/C MV 500MCM? -For 2 runs of 3/C MV 500MCM cable, Can I calculate R,X, and C values as R/2, X/2 and 2*C of the 1/C MV 500MCM cable?
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#1 "Re: R,X, & C for 1/C vs 3/C MV Cables" by RAMConsult on 09/09/2016 1:31 PM (score 2)

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#6 "Re: R,X, & C for 1/C vs 3/C MV Cables" by RAMConsult on 09/09/2016 10:02 PM (score 1)

RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#1 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 1:31 PM
	It depends upon how important the accuracy of the numbers is to you; especially since you have left out important details such as the physical arrangement of the cables, the materials surrounding them, etc. Go to the website of the manufacturer of the cable and download a copy of their cable engineering handbook which will have the answers to your questions (and more). You will also find this information useful for determining the ampacity, which will vary widely, depending upon your particular situation. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#2 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 1:32 PM
	Can you explain what the R,X, and C values refer to...? __________________ All living things seek to control their own destiny....this is the purpose of life
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davechow Active Contributor Join Date: Dec 2013 Posts: 10	#4 In reply to #2 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 4:46 PM
	Resistance, reactance, and capacitance. I need to compute these values as accurate as I can. Unfortunately no data available except for another 1/C MV 500MCM same cable manufacturer.
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SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#5 In reply to #4 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 5:05 PM
	http://s1.downloadmienphi.net/file/downloadfile6/192/1385052.pdf Right at the beginning.... __________________ All living things seek to control their own destiny....this is the purpose of life
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#3 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 3:19 PM
	...and do pick up the phone and talk to the cable manufacturer directly, as this is the best source of information - far better and quicker to obtain than via an anonymous international internet Engineering forum - the proverbial "horse's mouth". So many telephones these days. So little use being made of them these days. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#6 In reply to #3 Re: R,X, & C for 1/C vs 3/C MV Cables 09/09/2016 10:02 PM
	To paraphrase: So many ~~telephones~~ engineers these days. So little useful ones being made ~~of them~~ these days. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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7anoter4 Guru Join Date: Oct 2012 Location: 100 miles North from the World Center Posts: 879 Good Answers: 42	#7 Re: R,X, & C for 1/C vs 3/C MV Cables 09/10/2016 11:38 AM
	As already was said, it depends on the accuracy of calculation. R depends on material[copper for instance],insulation rated temperature[90oC for XLPE or EPR], skin effect[it depends on conductor resistance and frequency] and proximity effect[it depends, also, on the distance to the other conductor]. X it could be between conductor and ground [shield/screen],self reactance or between other conductor from vicinity. Capacitance could be between conductor and shield [or screen] or combined all phases together. __________________ Julius
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davechow Active Contributor Join Date: Dec 2013 Posts: 10	#8 Re: R,X, & C for 1/C vs 3/C MV Cables 09/10/2016 6:25 PM
	The accuracy is important. Two sets of cables, same manufacturer, same insulation, same everything except 3/C vs 1/C, Should R, X, and C be very close? and for 2 runs of the 3/C MV cables, Can I just calculate R,X, and C values as R/2, X/2 and 2*C of the 1/C (same everything else) cable?
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RAMConsult Guru Join Date: May 2007 Location: NYC metropolitan area. Posts: 3230 Good Answers: 444	#9 In reply to #8 Re: R,X, & C for 1/C vs 3/C MV Cables 09/10/2016 9:06 PM
	1.) If "...The accuracy is important...", then "...very close..." may not be good enough. 2.) Until you do the work suggested in post #1 above, the answer remains "No", especially if "...The accuracy is important..." to your client/company/future. __________________ “Tell me and I forget. Teach me and I remember. Involve me and I learn.” Ben Franklin.
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jack of all trades Guru Join Date: Sep 2006 Location: Auckland, New Zealand Posts: 8777 Good Answers: 376	#10 In reply to #8 Re: R,X, & C for 1/C vs 3/C MV Cables 09/11/2016 3:28 PM
	If accuracy is important get cable data from cable supplier, get calculation data from cable supplier website, obtain applicable electrical installation standard (eg IEC standard for European installations, etc), obtain installation drawings and check against above. The only way if you want accuracy (or hire a consultancy to do it for you). __________________ jack of all trades
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davechow Active Contributor Join Date: Dec 2013 Posts: 10	#11 Re: R,X, & C for 1/C vs 3/C MV Cables 09/11/2016 11:07 PM
	I already computed R, XL, and C for the 3/C cable, I have the R,X and C for 1/C which is from the manufacturer. My issue is that my calculations have 15% difference of 1/C datasheet parameters, Is this Ok or both should be very near? Same for 2 runs, I have computed these for 3/C but not near 1/C when divided R & X by 2 and multiplied C by 2.
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7anoter4 Guru Join Date: Oct 2012 Location: 100 miles North from the World Center Posts: 879 Good Answers: 42	#12 Re: R,X, & C for 1/C vs 3/C MV Cables 09/12/2016 12:00 AM
	See-for instance: http://www.kerite.com/Portals/0/HighVoltage/MU040_KRT-EngHandbook-lowres.pdf __________________ Julius
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#13

Re: R,X, & C for 1/C vs 3/C MV Cables

09/15/2016 12:14 PM

5kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
6	0.519 + j 0.115	0.803 + j 0.501	0.514 + j 0.050	0.880 + j 0.548
4	0.329 + j 0.110	0.619 + j 0.479	0.323 + j 0.047	0.694 + j 0.519
2	0.209 + j 0.104	0.506 + j 0.453	0.204 + j 0.043	0.577 + j 0.485
1	0.167 + j 0.100	0.468 + j 0.437	0.162 + j 0.041	0.536 + j 0.464
1/0	0.134 + j 0.098	0.438 + j 0.421	0.128 + j 0.039	0.504 + j 0.444
2/0	0.108 + j 0.095	0.414 + j 0.404	0.102 + j 0.038	0.477 + j 0.423
3/0	0.087 + j 0.092	0.395 + j 0.386	0.081 + j 0.037	0.455 + j 0.401
4/0	0.070 + j 0.090	0.380 + j 0.367	0.064 + j 0.035	0.436 + j 0.378
250	0.061 + j 0.087	0.371 + j 0.349	0.055 + j 0.034	0.423 + j 0.357
350	0.046 + j 0.083	0.354 + j 0.319	0.040 + j 0.033	0.400 + j 0.321
500	0.034 + j 0.079	0.338 + j 0.281	0.028 + j 0.032	0.376 + j 0.279
750	0.026 + j 0.074	0.319 + j 0.240	0.020 + j 0.030	0.349 + j 0.235
1000	0.022 + j 0.071	0.305 + j 0.213	0.016 + j 0.029	0.331 + j 0.207
1250	0.019 + j 0.070	0.290 + j 0.189	0.014 + j 0.031	0.311 + j 0.182
1500	0.018 + j 0.066	0.281 + j 0.171	0.012 + j 0.028	0.299 + j 0.164
1750	0.017 + j 0.064	0.272 + j 0.159	0.011 + j 0.028	0.288 + j 0.152
2000	0.016 + j 0.063	0.264 + j 0.148	0.011 + j 0.027	0.279 + j 0.141

8kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
6	0.520 + j 0.115	0.814 + j 0.474	0.514 + j 0.053	0.887 + j 0.510
4	0.329 + j 0.110	0.628 + j 0.453	0.323 + j 0.049	0.698 + j 0.483
2	0.209 + j 0.104	0.513 + j 0.429	0.204 + j 0.046	0.579 + j 0.452
1	0.167 + j 0.100	0.473 + j 0.412	0.162 + j 0.043	0.537 + j 0.432
1/0	0.134 + j 0.098	0.442 + j 0.398	0.128 + j 0.041	0.503 + j 0.414
2/0	0.108 + j 0.095	0.417 + j 0.382	0.102 + j 0.040	0.475 + j 0.394
3/0	0.087 + j 0.092	0.397 + j 0.365	0.081 + j 0.038	0.451 + j 0.374
4/0	0.070 + j 0.090	0.380 + j 0.347	0.064 + j 0.037	0.431 + j 0.353
250	0.061 + j 0.087	0.370 + j 0.330	0.055 + j 0.036	0.418 + j 0.333
350	0.046 + j 0.083	0.351 + j 0.297	0.040 + j 0.035	0.392 + j 0.296
500	0.034 + j 0.079	0.334 + j 0.266	0.028 + j 0.033	0.369 + j 0.262
750	0.026 + j 0.075	0.314 + j 0.228	0.020 + j 0.031	0.342 + j 0.222
1000	0.022 + j 0.071	0.298 + j 0.198	0.016 + j 0.031	0.320 + j 0.192
1250	0.019 + j 0.070	0.285 + j 0.181	0.014 + j 0.032	0.304 + j 0.174
1500	0.018 + j 0.066	0.275 + j 0.164	0.012 + j 0.029	0.292 + j 0.157
1750	0.017 + j 0.064	0.267 + j 0.152	0.011 + j 0.029	0.282 + j 0.145
2000	0.016 + j 0.062	0.259 + j 0.142	0.010 + j 0.028	0.273 + j 0.135

Assumptions:

(1) Single conductor cables horizontally spaced 8" on center
(2) Three conductor cables paralleled or triplexed
(3) Perfect transposition of phase conductors
(4) Cables supply balanced load

(5) 90°C conductor temperature (45°C shield temperature)
(6) Shield consists of 5 mil copper tape
(7) 100 meter-ohm earth
(8) Current returns in earth and shield as applicable.

CABLE SEQUENCE IMPEDANCE DATA
Three Phase - Copper Conductors - ohms/1,000 ft.
15kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
2	0.210 + j 0.104	0.518 + j 0.399	0.204 + j 0.048	0.577 + j 0.414
1	0.168 + j 0.100	0.477 + j 0.384	0.162 + j 0.046	0.534 + j 0.396
1/0	0.134 + j 0.097	0.444 + j 0.370	0.128 + j 0.044	0.499 + j 0.379
2/0	0.108 + j 0.095	0.418 + j 0.355	0.102 + j 0.042	0.470 + j 0.362
3/0	0.087 + j 0.092	0.397 + j 0.339	0.081 + j 0.041	0.445 + j 0.344
4/0	0.071 + j 0.089	0.379 + j 0.323	0.064 + j 0.039	0.424 + j 0.325
250	0.061 + j 0.087	0.367 + j 0.302	0.055 + j 0.038	0.408 + j 0.302
350	0.046 + j 0.083	0.347 + j 0.277	0.040 + j 0.036	0.384 + j 0.274
500	0.035 + j 0.079	0.329 + j 0.248	0.028 + j 0.035	0.360 + j 0.243
750	0.026 + j 0.074	0.308 + j 0.213	0.020 + j 0.033	0.333 + j 0.207
1000	0.022 + j 0.071	0.291 + j 0.187	0.016 + j 0.032	0.311 + j 0.180
1250	0.019 + j 0.070	0.279 + j 0.171	0.013 + j 0.033	0.296 + j 0.164
1500	0.018 + j 0.066	0.269 + j 0.155	0.012 + j 0.030	0.284 + j 0.148
1750	0.017 + j 0.064	0.260 + j 0.144	0.011 + j 0.030	0.274 + j 0.137
2000	0.016 + j 0.062	0.253 + j 0.135	0.010 + j 0.029	0.265 + j 0.128

25kV

1	0.168 + j 0.100	0.478 + j 0.360	0.162 + j 0.048	0.529 + j 0.366
1/0	0.134 + j 0.097	0.444 + j 0.347	0.128 + j 0.046	0.493 + j 0.351
2/0	0.108 + j 0.095	0.417 + j 0.333	0.102 + j 0.044	0.463 + j 0.335
3/0	0.087 + j 0.092	0.394 + j 0.313	0.081 + j 0.043	0.437 + j 0.314
4/0	0.071 + j 0.089	0.376 + j 0.298	0.064 + j 0.041	0.415 + j 0.297
250	0.061 + j 0.087	0.363 + j 0.284	0.055 + j 0.040	0.400 + j 0.281
350	0.046 + j 0.083	0.343 + j 0.260	0.040 + j 0.038	0.375 + j 0.255
500	0.035 + j 0.079	0.323 + j 0.234	0.028 + j 0.036	0.351 + j 0.228
750	0.026 + j 0.074	0.300 + j 0.198	0.020 + j 0.034	0.321 + j 0.191
1000	0.022 + j 0.071	0.285 + j 0.177	0.016 + j 0.033	0.303 + j 0.170
1250	0.019 + j 0.070	0.273 + j 0.162	0.013 + j 0.034	0.288 + j 0.155
1500	0.018 + j 0.066	0.263 + j 0.148	0.012 + j 0.031	0.277 + j 0.141
1750	0.017 + j 0.064	0.255 + j 0.137	0.011 + j 0.031	0.267 + j 0.131
2000	0.016 + j 0.062	0.247 + j 0.129	0.010 + j 0.030	0.258 + j 0.123

35kV

1/0	0.135 + j 0.097	0.438 + j 0.298	0.128 + j 0.050	0.476 + j 0.296
2/0	0.109 + j 0.095	0.400 + j 0.286	0.102 + j 0.048	0.445 + j 0.283
3/0	0.088 + j 0.092	0.386 + j 0.274	0.081 + j 0.046	0.419 + j 0.270
4/0	0.071 + j 0.089	0.366 + j 0.261	0.064 + j 0.045	0.397 + j 0.256
250	0.061 + j 0.087	0.353 + j 0.248	0.055 + j 0.043	0.382 + j 0.244
350	0.046 + j 0.083	0.331 + j 0.229	0.040 + j 0.041	0.357 + j 0.223
500	0.035 + j 0.079	0.309 + j 0.203	0.028 + j 0.039	0.330 + j 0.196
750	0.026 + j 0.074	0.286 + j 0.175	0.020 + j 0.037	0.302 + j 0.168
1000	0.022 + j 0.071	0.271 + j 0.157	0.016 + j 0.036	0.285 + j 0.151
1250	0.019 + j 0.070	0.259 + j 0.145	0.013 + j 0.035	0.271 + j 0.139
1500	0.018 + j 0.066	0.250 + j 0.133	0.012 + j 0.033	0.261 + j 0.127
1750	0.017 + j 0.064	0.242 + j 0.124	0.011 + j 0.033	0.252 + j 0.118
2000	0.016 + j 0.062	0.235 + j 0.117	0.010 + j 0.032	0.244 + j 0.111

CABLE SEQUENCE IMPEDANCE DATA
Three Phase - Copper Conductors - ohms/1,000 ft.
46kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
4/0	0.071 + j 0.089	0.357 + j 0.237	0.065 + j 0.047	0.383 + j 0.231
250	0.062 + j 0.087	0.344 + j 0.226	0.055 + j 0.045	0.368 + j 0.220
350	0.046 + j 0.083	0.321 + j 0.209	0.040 + j 0.043	0.343 + j 0.202
500	0.035 + j 0.079	0.301 + j 0.189	0.028 + j 0.041	0.319 + j 0.182
750	0.026 + j 0.074	0.278 + j 0.164	0.020 + j 0.038	0.292 + j 0.157
1000	0.022 + j 0.071	0.263 + j 0.148	0.016 + j 0.037	0.276 + j 0.141
1250	0.020 + j 0.070	0.251 + j 0.137	0.013 + j 0.038	0.262 + j 0.131
1500	0.018 + j 0.066	0.243 + j 0.125	0.012 + j 0.034	0.252 + j 0.120
1750	0.017 + j 0.064	0.235 + j 0.117	0.011 + j 0.034	0.244 + j 0.112
2000	0.016 + j 0.062	0.228 + j 0.111	0.010 + j 0.033	0.236 + j 0.106

69kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
4/0	0.071 + j 0.089	0.337 + j 0.199	0.065 + j 0.051	0.355 + j 0.192
250	0.062 + j 0.087	0.324 + j 0.191	0.055 + j 0.049	0.341 + j 0.184
350	0.046 + j 0.083	0.301 + j 0.177	0.040 + j 0.047	0.316 + j 0.170
500	0.035 + j 0.079	0.281 + j 0.161	0.028 + j 0.044	0.294 + j 0.155
750	0.026 + j 0.074	0.259 + j 0.141	0.020 + j 0.041	0.269 + j 0.135
1000	0.022 + j 0.070	0.245 + j 0.129	0.016 + j 0.041	0.254 + j 0.123
1250	0.020 + j 0.070	0.234 + j 0.121	0.013 + j 0.041	0.242 + j 0.115
1500	0.018 + j 0.066	0.226 + j 0.111	0.012 + j 0.037	0.233 + j 0.106
1750	0.017 + j 0.064	0.219 + j 0.104	0.011 + j 0.036	0.225 + j 0.099
2000	0.016 + j 0.062	0.213 + j 0.099	0.010 + j 0.035	0.219 + j 0.094

115kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
500	0.035 + j 0.079	0.248 + j 0.127	0.028 + j 0.049	0.255 + j 0.122
750	0.026 + j 0.074	0.228 + j 0.113	0.020 + j 0.046	0.234 + j 0.109
1000	0.022 + j 0.070	0.216 + j 0.105	0.016 + j 0.044	0.221 + j 0.100
1250	0.019 + j 0.070	0.206 + j 0.100	0.013 + j 0.045	0.211 + j 0.096
1500	0.018 + j 0.066	0.199 + j 0.092	0.012 + j 0.041	0.204 + j 0.088

138kV

	Three 1/C Cables		3/C Cable
Size (AWG/kcmil)	Positive/Negative	Zero Sequence	Positive/Negative	Zero Sequence
500	0.035 + j 0.078	0.231 + j 0.114	0.029 + j 0.052	0.236 + j 0.110
750	0.026 + j 0.074	0.212 + j 0.102	0.020 + j 0.048	0.216 + j 0.099
1000	0.022 + j 0.070	0.201 + j 0.095	0.016 + j 0.046	0.205 + j 0.091
1250	0.019 + j 0.070	0.192 + j 0.091	0.014 + j 0.047	0.196 + j 0.088
1500	0.018 + j 0.066	0.186 + j 0.084	0.012 + j 0.043	0.189 + j 0.081

Assumptions:

(1) Single conductor cables horizontally spaced 8" on center
(2) Three conductor cables paralleled or triplexed
(3) Perfect transposition of phase conductors
(4) Cables supply balanced load

(5) 90°C conductor temperature (45°C shield temperature)
(6) Shield consists of 5 mil copper tape
(7) 100 meter-ohm earth
(8) Current returns in earth and shield as applicable.

It seems to me ,the new Kerite catalogue does not refer to the 3/c conductor cables.

I’ll try to insert an old Kerite table-it has to be obsoleted now, I think.

__________________
Julius