Omicron CMC 430, Руководство пользователя

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3.18 How to read the specifications stated in this chapter
OMICRON builds exceptionally accurate, rugged and reliable protection testing equipment and
calibrators. For typical protection testing applications, the
CMC 430 is a magnitude more accurate
than the device under test. For calibration applications, however, a solid understanding of the
specifications is critical for a proper assessment whether the
CMC 430 is suitable for a certain
application. The following subsections provide a deeper insight how the specifications are to be read
and shows by example how to use them.
The specifications stated in this chapter try to specify all factors that could influence the accuracy of
the
CMC 430 , for example:
• Environmental conditions (temperature, humidity, altitude, shock, vibration)
• Operating conditions (amplitude, frequency, load, etc.)
• Aging or long-term drift
3.18.1 Calibration interval
CMC 430 test sets are calibrated to be traceable to the applicable standards or by national metrology
institutes. However, all electronic components are subject to drift over time. To ensure proper
operation of the
CMC 430 according to the published specifications, it has to be recalibrated regularly.
OMICRON defines one or more calibration intervals in the specifications. The specifications stated for
the
CMC 430 are dimensioned in a way that 99 % of all test sets meet the specifications at the end of
the calibration interval, which corresponds to 2.6 standard deviations for a statistical normal
distribution. OMICRON test sets often work much longer within the specifications than the specified
calibration interval. This mainly depends on the frequency of use and the harshness of the
environmental conditions. This is why the calibration quality standard ISO/IEC 17025 states that
calibration laboratories must not recommend any calibration interval in the test report if not previously
agreed with the customer.
For devices that are exposed to high stress, the accuracy of the test set should be checked by cross-
checking the measurement results with traceable reference equipment, either on a regular basis or
prior to use. This can be accomplished by using measurement equipment that fulfills the requirements
of the specific application.
Users always should evaluate the recalibration data for their product to ensure that the selected
intervals meet their requirements for quality and reliability, irrespective of whether they select a
recalibration interval based on the published specification or by any other means.
3.18.2 Examples for amplifier accuracy
3.18.2.1 Higher ambient temperature (AC)
When operating the CMC 430 at ambient temperatures beyond 23 °C ± 5 °C, the temperature
coefficient has to be taken into account.
Set value: I
set
= 1 A, 50/60 Hz
Range: I
range
= 1.25 A
Ambient temperature: T
ambient
= 40 °C
Technical data
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