urd cable rehabilitation program
DESCRIPTION
URD Cable Rehabilitation Program. SWEDE 2009 Tulsa, OK May 7, 2009. B. Shawn Cobb, P.E. Presentation Objective. Update on URD System Performance URD System History URD System & Performance Statistics Current Status Action Plan Answer Questions. What is a URD System?. - PowerPoint PPT PresentationTRANSCRIPT
URD Cable Rehabilitation Program
SWEDE 2009
Tulsa, OK
May 7, 2009 B. Shawn Cobb, P.E.
2
Presentation Objective
Update on URD System Performance URD System History URD System & Performance Statistics Current Status Action Plan Answer Questions
3
What is a URD System?
Underground Residential Distribution Single-phase underground electric distribution
system Provides electric service to residential
customers in subdivisions Typically utilizes a loop feed design (two
sources) feeding many sections of cables in between transformers
4
URD System History
1939 – Earliest URD system in Danvers Subdivision 1964 – Installed first direct-buried URD systems 1984 – Initiated a cable replacement program based on
failure rate 1986 – Began installing cable in conduit for new URD
primary cable installations 1993 – Cable injection was introduced for 13kV cables 1999 – Cable injection was developed for 35 kV cables
5
URD System&
Performance Statistics
6
Direct-buried URD
The total amount of direct-buried URD cable installed between 1964 and 1986 is 1,628 miles
The oldest remaining direct-buried cable is 38 years old
Direct-buried URD cable was not performing well (high failure rates), so a cable rehabilitation program was initiated in 1984.
7
URD Direct-buried Cable
DIRECT-BURIED URD CABLEREHABILITATED vs REMAINING
96
396 455
681
13KV REHABILITATED MILES
13KV REMAINING MILES
35KV REHABILITATED MILES
35KV REMAINING MILES
8
URD Direct-buried Cable
DIRECT-BURIED URD CABLEALL REMAINING CABLE by VOLTAGE
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
YEAR
MIL
ES
35KV Cable Injection (Sum)
35KV Non-Rehab
13KV Cable Injection (Sum)
13KV Non-Rehab
9
URD Direct-buried Cable
DIRECT-BURIED URD CABLEREMAINING NON-REHABILITATED CABLE by VOLTAGE
0
200
400
600
800
1,000
1,200
1,400
1,600
1,800
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
MIL
ES
35kV
13KV
10
URD Direct-buried Cable
DIRECT-BURIED URD CABLEREHABILITATED CABLE by VOLTAGE
0
20
40
60
80
100
120
140
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
YEAR
MIL
ES
35KV Cable Injection
35KV Replacement
13 KV Cable Injection
13KV Replacement
11
URD Direct-buried CableDIRECT-BURIED URD CABLE
CABLE REPLACEMENT by VOLTAGE
0
20
40
60
80
100
120
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
MIL
ES 35KV Replacement
13KV Replacement
12
URD Direct-buried Cable
DIRECT-BURIED URD CABLEINJECTED CABLE by VOLTAGE
0
5
10
15
20
25
30
35
40
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
YEAR
MIL
ES
35kV
13KV
13
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEM FAILURESTOTAL FAILURES
by TYPE
0
200
400
600
800
1,000
1,200
1,400
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
No.
of F
ailu
res TOTAL MISC
TOTAL CONNECTIONS
TOTAL TRANSFORMERS
TOTAL CABLE
14
URD Direct-buried System Failures
13KV DIRECT-BURIED URD SYSTEM FAILURES
0
50
100
150
200
250
300
350
400
450
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
No.
of F
ailu
res 13KV MISC
13KV CONNECTIONS
13KV TRANSFORMERS
13KV CABLE
15
URD Direct-buried System Failures
35KV DIRECT-BURIED URD SYSTEM FAILURES
0
100
200
300
400
500
600
700
800
900
1000
1100
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
No.
of F
ailu
res 35KV MISC
35KV CONNECTIONS
35KV TRANSFORMERS
35KV CABLE
16
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEMTOTAL FAILURE PERCENTAGES
TOTAL MISC1%
TOTAL TRANSFORMERS42%
TOTAL SPLICES5%
TOTAL CONNECTIONS12%
TOTAL CABLE40%
17
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEM13KV FAILURE PERCENTAGES
13KV SPLICES3%
13KV MISC0%
13KV CONNECTIONS10%
13KV TRANSFORMERS36%13KV CABLE
51%
18
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEM35KV FAILURE PERCENTAGES
35KV MISC1%
35KV SPLICES5%
35KV CONNECTIONS13%
35KV TRANSFORMERS47%
35KV CABLE34%
19
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEM FAILURESTOTAL FAILURES
by VOLTAGE
0
200
400
600
800
1,000
1,200
1,400
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
20
06
20
08
No
. of
Fa
ilure
s
35KV TOTAL
13KV TOTAL
20
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEMCABLE FAILURES
by VOLTAGE
0
100
200
300
400
500
600
700
1966
1968
1970
1972
1974
1976
1978
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
No.
of F
ailu
res
35KV CABLE
13KV CABLE
21
URD Direct-buried System Failures
DIRECT-BURIED URD SYSTEMTRANSFORMER FAILURES
by VOLTAGE
0
100
200
300
400
500
19
66
19
68
19
70
19
72
19
74
19
76
19
78
19
80
19
82
19
84
19
86
19
88
19
90
19
92
19
94
19
96
19
98
20
00
20
02
20
04
20
06
20
08
No
. of
Fa
ilure
s
35KV TRANSFORMERS
13KV TRANSFORMERS
22
URD Direct-buried System Failures
FAILURE RATES(Total Failures)
0.62
0.50
0.75
1.11
0.54
0.30
0.00
0.20
0.40
0.60
0.80
1.00
1.20
Failu
re R
ate
(fai
lure
s/m
ile)
Failure Rate
23
URD Direct-buried System Failures
FAILURE RATES(by Voltage)
0.46
1.21
0.91
0.73
0.47
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Failu
re R
ate
(fai
lure
s/m
ile)
35 kV
13 kV
24
Through the Cable Rehabilitation Program, we have replaced 884 miles of direct-buried cable with cable in conduit and have injected 251 miles with the injection process. This leaves us with 493 miles of direct-buried cable that still need to be addressed.
The current contractor cost to replace direct-buried cable with cable in conduit is $160,000 per mile.
The current cost for cable injection is $75,000 per mile.
Current Status
25
With an annual budget of $4.5 Million, the recommendation is to continue replacing direct-buried cable with cable in conduit and injecting cable with silicon. The proposed plan is to replace 15 miles with cable in conduit and to inject 30 miles.
1. This recommendation will maximize the use of our annual budget. 2. Cable injection will address and reduce our cable failure rate. 3. Cable replacement will address and reduce transformer failures. 4. Injection contractor has one full time crew which maximizes their
efficiency and productivity by injecting 30 miles of direct-buried cable per year.
Action Plan
26
At a rate of 45 miles per year, it will take
approximately 11 years to rehabilitate all of the remaining direct buried cable. At the completion of the program, there will be about 390 miles of injected cables. The remainder will be cable in conduit.
The recommendation was not based solely on financial calculations. The cable replacement also addresses the transformers, while the cable injection process does not.
Proposed Plan (cont)
27
Questions?