Eaton CMD, Руководство пользователя

Страница: 32 / 43

2 Engineering
2.5 Mean time to dangerous failure MTTFD
CMD(220-240VAC), CMDB 12/17 MN121002ZU-DEEN www.eaton.com
27
For channel 2 the DC
avg
for the CMD was calculated at DC
avg
= 90 %.
The undervoltage release can be estimated a DC
avg
= 60 % provided that
regular inspections are carried out.
The generally recognized inspection frequency is a hundred times more
often than the MTTF
D
. The test interval can be determined from:
2.5 Mean time to dangerous failure MTTF
D
The MTTF
D
time for the assembly parts is based on
where: B
10D
: Lifespan up to a dangerous failure ( ￫ table 1 and ￫ table 2).
n
op
: average number of annual switch operations
The MTTF
D
time for the CMD contactor monitoring device was calculated at
MTTF
D
= 125 years. This value is based on a maximum operating frequency
of 350,400 operations/year (1 operation per minute, 16 hours per day, 365
days a year).
The MTTF
D
time of the contactors depends on the application. The utilization
category in accordance with IEC/EN 60947-4-1 and the operating frequency
are an important factor here. Depending on the utilization category, the
following values can be applied to B
10D
, ￫ table 1, page 28.
￫
The function of the undervoltage release must be tested
manually at regular intervals.
T
Test
=
MTTF
D
(formula 1)
100
￫
It is recommended that the test is carried out under no-load
conditions.
MTTF
D
=
B
10D
(formula 2)
0.1 x n
op