 |
MTBF Data
for Connectivity Products
|
| SIXNET
calculates the actual installed experience of our customers in calculating
the Mean Time Between Failure (MTBF) data we publish. We use a conservative
estimate of only 70% of units shipped being in service and a usage
per day of 12 hours. There
are several methods to calculate MTBF. Most often manufacturers
quote theoretical calculations that are based upon statistics
computed about the components used in the product. We have chosen
instead to report actual results, which are gathered from our
ISO9001 traceable shipments and return/repair records. |
|
| |
MTBF
Data (updated May 2005): (see
below for how we calculate MTBF)
| Product
|
#
of Units
Sampled |
Average
Units /
month
(A)
|
Total
Unit
Months
(A
x 78)
|
Total
Unit
Hours
(A
x 78 x .7
x 12 x 30)
|
Applicable
Failures |
MTBF
(see
notes) |
Ethernet
Switches |
9,135 |
761 |
59,378 |
14,963,130 |
13 |
1,151,010
|
Industrial
Modems |
5,940 |
495 |
38,610 |
9,729,720 |
19 |
512,091
|
| Modbus
Gateways |
7,787
|
649 |
50,616 |
12,755,106 |
17 |
750,300
|
Notes:
> These MTBF numbers are
based on data for a sampling of units over a time span of
one year. |
|
MTBF Calculation:
First,
based on a sampling of actual units, we determine the average number
of units being installed per month (A). Second, we determine the
number of months in the sampling interval (B). We then can calculate
the total number of "unit months" that these units have
been in the field (C). ((A
x 1) + (A x 2) + … + (A x B)) = C (total number of unit months
in the field)
(Note: For
a twelve-month period, you would multiply 78 times the average
number of units installed per month.)
Next, we assume
an installation rate of 70% of what we shipped and 12 hours operation
per day on the average. From this we can calculate the total number
of "unit operating hours" (D) as follows:
C
(from above) x 70% x 12 hours/day x 30 days/month = D (total number
of unit operating hours)
Finally, to
get the MTBF we divide the total number of unit operating hours
by the number of applicable failures. An applicable failure is
one that cannot be attributed to misuse (i.e. over-voltage, forklift
impalement, etc.), Mother Nature (i.e. lightning, flooding, etc.)
or other returns that are not related to manufacturing defects.
(Total
number of unit operating hours) / (number of chargeable failures)
= MTBF |
|
Certified
to Perform
 |
| About
Us | Sales
| Support
| What's
New | WebStore
| Contact
| Advanced
Search 
