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kjinite
4096 Hybrid Key Telephone System
GENERAL DESCRIPTION
The
Mean
Time
Between
Failure
(MlBF)
for
each
component
of the 4096
Key Telephone
System
is shown
in Table 200-16.
The MTBF
figures
are calculated
based on:
l
Specifications:
BellCoRe
'TR-TSY-
000332"
l
Quality
Factor:
Level 2
l
Environmental
Factor:
Group
Benign
(1.0)
l
Method:
Parts Count
Method
MeanlIme
Between
Failure
@'vlTBF) represents
for a particular
interval,
the total functlontng
life of a population
of an item divided
by the
number
of failures
with&r the population
dur-
ing the measurement
Interval.
The deffnitlon
holds
for the
time,
cycles, miIes,
events,
or
other
measures
of life units.
This does NOT
provide
a
definite
failure
tfme but
only indi-
cates
possible
failure
probabilities
based
on
calculations.
To calculate
a particular
systems
MTBF:
1. multfpiy
the quantity
of each component
,
ln the system by its failure
rate.
Component
Q,y
K
Fa&;
Resultant
Power
1 SUPPlY
I
2
x
2064.2
4128.4
2. Add
the resultants
from
step
1 for all
components
used to configure
a system.
3. Divide the total number
derived
from step
2 fntn
1.000.000.000.
This will provfde
the system's MTBF rated in hours.
1 .ooo,ooo.ooo
I
System
lVil73F
I
Total fkom
=
Step 2
Rated in
Hours
Table 200-16 Mean Time Between Fatlures (MTBF)
DEVICE
Basic Key Service Unit (BKSUI
Expansion
Key Service Unit IEKSUI
Power SuppIy
Unit (PSI
DC/DC
Converter
(DC/DC)
Central
Processor
Board (CPBI
Central
O&e
Interface
Board (COB)
Key Statton
Interface
Board (KIB)
Single I&e
Interface
Board (SIB)
AppIicaUon
Board (APL)
RS-232C
Module
IRSMI
Single Line MMF-RS
unit
(SLUI
Power Fatlure
Transfer
Unit Ipm
Ring Generator
Unit (RG)
Battery
Chargfng
Unit (BCI
Key Telephone
DSS/DLS
Console
Phone Box
FAXLURE F!ATE
MIBFINHOURS
Ml?BFMYEARS
(for
a single unit)
(for a sing,Ie utit)
574.7
1749038.3
198.6
356.9
2601905.3
319.9
2064.2
484449.2
55.3
4160.0
240384.6
27.4
16179.3
61807.4
7.1
9341.4
107050.3
12.2
5093.0
196347.9
22.4
10677.4
93655.8
10.7
7818.7.
127898.5
14.6
1212.4
824610.3
94.2
825.2
1211827.4
138.3
1615.0
619195.0
70.7
1509.0
662690.5
75.6
2310.6
432788.0
49.4
6022.9
166933.0
19.0
2511.3
3986200.1
45.5
4209.2
237574.8
27.1
Issue 1, January 1992
200-17
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