Calculation of reliability of linear structures fots
For FOCL length L parameter flow failure is determined by the expression [14]:
, (8.1)
where
– failure rate of i-th homogeneous section of the line, 1/hr;
– length
of the i-th section
of FOCL
with the appropriate intensity of failures.
Failure rates depends on the terrain laying OF (Table 8.1), according to [12] Ukraine is divided into 3-parts (Carpathians mountains, plains, the Black and Azov Seas).
In
Table. 8.1 there are the average characteristics of reliability
(failure rate (λ) and recovery time communication (
)
on the cable lines) derived from the results of a transport
telecommunications network in Ukraine from 2001 to 2005.
Table 8.1 - Values of failure rate per kilometer and average recovery time for connection of armorless underground OF
Region of Ukraine
|
Інтенсивність відмов на один кілометр траси ( ·10-7, 1/год) і середній час відновлення зв'язку, год |
|||||||
armored cable in the ground |
armorless cable in a polymer tube (subchannel) |
|||||||
|
|
|
|
|
|
|
|
|
mountain Carpathians |
- |
- |
- |
- |
- |
- |
- |
- |
plain area |
18,90 |
32,30 |
5,49 |
3,520 |
15,30 |
26,8 |
3,68 |
3,71 |
the coasts of Black and Azov Seas |
9,22 |
13,90 |
4,54 |
3,850 |
7,45 |
11,40 |
3,52 |
4,93 |
Mean
time between failures (h) on FOCL is calculated using the expression
[14, 15]: 
. (8.2)
Average communication recovery time (h), the mean values for different regions of Ukraine (eg, plain and Black) kept by the expression:
, (8.3)
where
–
the average recovery time due to the plain and the Black Sea regions
respectively, h.
Availability index of FOCL is determined by the expression [14, 15]:
, (8.4)
In
this case, there is a case where the statistical material in a very
limited volume is not possible in advance to find unknown
distribution law of the random variable
and
.
To characterize the accuracy assessment of these random variables using the concept of probability confidence γ .
If you put that data statistical studies on the specific gravity bounce FOCL correspond in practice exponential distribution law developments that are widely used to refuse
Confidence limits of the mean values and is determined by the expression:
, (8.5)
where
,
– upper and lower limits of the mean values of
statistical characteristics;
,
–
coefficients of upper and lower limits for a given probability of
confidence respectively;
– середнє
average quantitative reliability characteristics.
In this chapter equals:
,
or
(8.6)
The
obtained values of
reliability
and
,
for example, by the expressions (8.1) - (8.3) indicate on that the
basis of statistical data can be expected that fiber optic will be
within
та
.
Compare
the obtained values of
the coefficient of readiness cable line with a value that is required
(
).
For
determination of
according
to [14,
15]
it
is necessary to calculate the mean time between failures
(
)on
the length of the cable line, based on the standards of the average
time between failures
=
340,5 hours in length range of hypothetical reference length L = 2500
km and regulations mean time to reconnect
h
from
equation:
, (8.7)
. (8.8)
Than 
. (8.9)
If
,
it means that the reliability of
FOCL
meet norms.