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Section 4.13
Reliability
The 'bath-tub' curve shows how the failure rate of a power supply
develops over time. It is made up of three separate stages.
Immediately after production, some units fail due to defective
components or production errors. To ensure that these early
failures do not happen while in the possession of the user,
Excelsys carries out a burn-in on each unit, designed to ensure
that all these early failures are detected at Excelsys. After this
period, the power supplies fail very rarely, and the failure rate
during this period is fairly constant. The reciprocal of this failure
rate is the MTBF (Mean Time Between Failures).
At some time, as the unit approaches its end of life, the first
signs of wear appear and failures become more frequent.
Generally 'lifetime' is defined as that time where the failure rate
increases to five times the statistical rate from the flat portion of
the curve.
In summary, the MTBF is a measurement of how many devices
fail in a period of time (i.e. a measure of reliability), before signs
of wear set in. On the other hand, the lifetime is the time after
which the units fail due to wear appearing.
The MTBF may be calculated mathematically as follows:
MTBF = Total x t / Failure , where
Bathtub Reliability curve
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UltiMod Designer Manual
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Consult the UltiMod Configurator for further derating
information at
http://www.excelsys.com/xgen_configurator/configure.html.
Section 4.11
powerPac Options
Reverse Fan (Option 02)
The UltiMod is available with reverse air flow direction. This is
ideal to expel air from the system and works particularly well
withthe internal fan cooling built into the overall system. Contact
factory for details.
Ultra Low Leakage Current (Option 04)
The UltiMod is available with the option of Ultra Low Earth
Leakage Current of <150µA. This is ideal for Medical
applications using two power supplies or containing additional
parts that contribute to the system Earth Leakage Current,
ensuring system Earth Leakage current does not exceed levels
defined in EN60601-1 and UL60601-1 2nd and 3rd Editions.
Conformal Coating (Option C)
UltiMod is available with conformal coating for harsh
environments and MIL-COTs applications. It is IP50 rated
against dust and protected against vertical falling drops of
water and non condensing moisture, e.g. UX6ABDDL0C00
is a conformal coated 1000W configured UltiMod.
Input Cable Option (Option D)
3 Wire input mains cable. Input cables are 300mm in length and
come supplied with fast on connectors. See Section 4.7 for
mechanical drawing.
Section 4.12
Power Ratings
When specifying an UltiMod power supply in an application it is
necessary to ensure that powerPac s and powerMod s are
operating within their power output capabilities, taking into
account the Temperature Derating and Input Voltage Derating.
powerMod s are designed to provide maximum output power at
the nominal output voltages. The maximum permissible output
power that may be drawn from any powerMod is given in the
powerMod specification table in Section 4.6.