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EYE ON FIBER
Volume 2, Issue 4
2006
Evaluation of the Cleave and Crimp Connector Installation Method
Executive Summary
Pearson Technologies evaluated the performance of 40 SC cleave and leave connectors with the 62.5 µm fiber. The average TIA/EIA-568 B bi-directional insertion losses were –0.39 and –0.43 dB/pair. These loss values, slightly higher than those of connectors installed with an adhesive, are acceptable for data communications networks. The yield for these connectors, 94.7%, was acceptable. The yield was approximately the same as that for connectors installed with adhesive.
Introduction
In this report, we present the results of an evaluation of cleave and leave, SC connectors from Corning Cable Systems. The primary purpose of this evaluation was to determine the typical loss, in dB/pair, that an installer would expect to achieve. The second purpose was to determine the process yield, in percent, that an installer would expect to experience. The ultimate purpose of this evaluation was verification of the values stated in product data sheets.
Connector Installation Procedure
Pearson Technologies installed all connectors according with the following procedure:
Removal of the cable jacket,
Trimming of the strength members flush with the jacket,[1]
Removal of the tight buffer tube and primary fiber coating,
Cleaning of the fiber,[2]
Cleaving of the fiber to a cleave length of 8.5 ±0.5 mm,
Insertion of the fiber into the connector and
Crimping of the connector to the fiber and the tight buffer tube.
Pearson Technologies substituted an Alcoa Fujikura (AFL) cleaver, part number CT07 (Figure 1), for the cleaver included as part of the manufacturers kit. With this substitution, Pearson Technologies evaluated the cleave-and-leave connectors, not the cleave-and-leave installation process.
The reason for this substitution was the improved cleave angle produced by the CT07 cleaver (Eye on Fiber, Volume 1, Issue 2). The CT07, which has a list price of about $1500, produces a cleave angle lower than that of lower cost cleavers. Also, our experience indicates reduced connector loss and increased process yield with the AFL cleaver as compared with those obtained with low cost cleavers.
Evaluation Procedure
We installed one connector on the end of a long length of cable on a reel. With an 850 nm OTDR[3], we measured the loss of that connector. If the loss of that connector were low, we cut eight feet of cable from the reel and installed a connector on the opposite end. This procedure enabled our determination of the end with high loss, if high loss occurred.
We measured the loss of the eight-foot patch cord in accordance with TIA/EIA-568 B, which requires measurement according to Method B of TIA/EIA-526-14 A. The reference leads were qualified with losses of better than -0.5 dB according to TIA/EIA-526-14 A.[4]
Method B requires a loss measurement of two connector pairs. With the TIA/EIA-568 B requirement that connector loss be less than 0.75 dB/pair, we would expect all measurements to be less than 1.5 dB.
Results
We installed 40 Corning Cable System SC connectors on 62.5 µm tight tube cable.[5] We present the results in Table 1. Because of operator error, we ignored the results from two connectors (connectors 1 and 21). With two exceptions (numbers 7 and 31), the connectors had acceptable insertion losses of better than -1.5 dB.
Table 1 indicates low loss, an average of -0.39 and -0.43 dB/pair in opposite directions. This loss is higher than that of typical connectors requiring adhesives and polishing. Such connectors with ceramic ferrules have typical values of -0.30 dB/pair.[6]
These measured losses would be expected to be higher than the losses of adhesive and polish connectors due to the mechanical splice in the back shell of the cleave-and-leave connector. If we assume that the ferrules of the Corning connectors provide a typical loss of -0.30 dB/pair, the measured insertion losses imply an average mechanical splice loss of -0.05 to -0.065 dB/ connector. Such a low loss is impressive. The, low loss values support the data sheet typical value of 0.4 dB/pair.
Table 1 indicates an acceptable, high yield of 94.7 %. Professional installers expect field yields of 95- 98 %.
Comments and Observations
The results presented herein apply to multimode connectors installed with the CT07 cleaver. We expect both loss and yield of cleave-and-leave, multimode connectors installed with a low cost cleaver to be inferior to those values presented herein.[7]
Conclusions
With the assumption that the loss and yield performance of the connectors used in this evaluation are the same as those obtained from connectors purchased through any distribution source, we conclude that cleave-and-leave connectors offer power loss and yield that are acceptable. Although the loss of these connectors is higher than that of adhesive connectors, the small increase, approximately 0.1 dB per pair, is inconsequential to operation of data networks based on data standards. The equivalence of cleave-and-leave yield with adhesive connector yield implies the possibility of a favorable cost comparison with adhesive connectors. Assuming an appropriate connector cost, the high installation rate of cleave-and-leave connectors may result in a total installed cost that is less than that for adhesive connectors.
Table 1: Evaluation Data
|
|
|
|
TIA/EIA-568 B Insertion Loss |
|
|
||
|
U-# |
|
OTDR loss |
odd # @ Source |
even # @ Source |
Status |
||
|
1 |
|
|
|
|
|
broken fiber; operator error; do not count |
|
|
2 |
|
-0.42 |
|
-0.58 |
G |
|
|
|
3 |
|
|
-0.58 |
|
G |
|
|
|
4 |
|
-0.46 |
|
-0.43 |
G |
|
|
|
5 |
|
|
-0.54 |
|
G |
|
|
|
6 |
|
-0.32 |
|
-1.09 |
G |
|
|
|
7 |
|
|
|
|
NG |
was -1.54/-1.60 |
|
|
8 |
|
|
|
-1.16 |
G |
replaced #7 |
|
|
9 |
|
-0.40 |
-1.05 |
|
G |
|
|
|
10 |
|
|
|
-1.00 |
G |
|
|
|
11 |
|
-0.47 |
-0.78 |
|
G |
|
|
|
12 |
|
|
|
-0.85 |
G |
|
|
|
13 |
|
-0.41 |
-0.77 |
|
G |
|
|
|
14 |
|
|
|
-1.02 |
G |
|
|
|
15 |
|
-0.35 |
-1.20 |
|
G |
|
|
|
16 |
|
|
|
-1.13 |
G |
|
|
|
17 |
|
-0.35 |
-1.17 |
|
G |
|
|
|
18 |
|
|
|
-1.36 |
G |
|
|
|
19 |
|
-0.32 |
-0.94 |
|
G |
|
|
|
20 |
|
|
|
-0.72 |
G |
|
|
|
21 |
|
|
|
|
G |
operator error; do not count |
|
|
22 |
|
-0.36 |
|
-0.66 |
G |
|
|
|
23 |
|
|
-0.50 |
|
G |
|
|
|
24 |
|
-0.06 |
|
-0.68 |
G |
|
|
|
25 |
|
|
-0.63 |
|
G |
|
|
|
26 |
|
-0.40 |
|
-0.61 |
G |
|
|
|
27 |
|
|
-0.55 |
|
G |
|
|
|
28 |
|
-0.23 |
|
-1.07 |
G |
|
|
|
29 |
|
|
-0.69 |
|
G |
|
|
|
30 |
|
-0.27 |
|
-0.81 |
G |
|
|
|
31 |
|
|
|
|
NG |
was -5.28/-5.36 |
|
|
32 |
|
|
|
-0.67 |
G |
replaced # 31 |
|
|
33 |
|
-0.34 |
-0.86 |
|
G |
|
|
|
34 |
|
|
|
-1.01 |
G |
|
|
|
35 |
|
-0.44 |
-0.48 |
|
G |
|
|
|
36 |
|
|
|
-0.74 |
G |
|
|
|
37 |
|
-0.42 |
-0.98 |
|
G |
|
|
|
38 |
|
|
|
-0.92 |
G |
|
|
|
39 |
|
-0.38 |
-0.73 |
|
G |
|
|
|
40 |
|
|
|
-0.54 |
G |
|
|
|
|
|
|
|
|
|
|
|
|
|
average= |
-0.36 |
-0.78 |
-0.85 |
dB |
|
|
|
|
|
|
|
|
|
|
|
|
|
yield= |
94.7% |
36 |
38 |
|
|
|
|
|
average= |
|
-0.39 |
-0.43 |
dB/pair |
|
|
|
standard deviation |
0.25 |
0.26 |
dB/ two pairs |
|
|||
|
|
|
|
0.16 |
0.13 |
dB/pair |
|
|
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