11 Maintenance
C232-302-401/402/403/404-603 / C232/EN M/A23 11-1
11 Maintenance
The C232 is a low-maintenance device. The components used in the units are selected
to meet exacting requirements. Recalibration is not necessary.
Maintenance procedures in
the power supply area
Electrolytic capacitors are installed in the power supply area because of dimensioning
requirements. The useful life of these capacitors is significant from a maintenance
standpoint. When the equipment is operated continuously at the upper limit of the
recommended temperature range (+55°C or 131°F), the useful life of these components
is 80,000 hours, or more than 9 years. Under these conditions, replacement of the
electrolytic capacitors is recommended after a period of 8 to 10 years. Component drift
follows the '10-degree rule'. This means that the useful life is doubled for each 10 K
reduction in temperature. When the operating temperatures inside the devices are
lower, the required maintenance intervals are increased accordingly.
Replacement of the maintenance-related components named above is not
possible
without soldering. Maintenance work must be carried out by AREVA service personnel
only.
Routine functional testing
The C232 is used as a safety device and must therefore be routinely checked for proper
operation. The first functional tests should be carried out approximately 6 to 12 months
after commissioning. Additional functional tests should performed at intervals of 2 to 3
years – 4 years at the maximum.
The C232 incorporates in its system a very extensive self-monitoring function for
hardware and software. The internal structure guarantees, for example, that
communication within the processor system will be checked on a continuing basis.
Nonetheless, there are a number of subfunctions that cannot be checked by the self-
monitoring feature without running a test from the device terminals. The respective
device-specific properties and setting parameters must be observed in such cases.
In particular, none of the control and signaling circuits that are run to the device from the
outside are checked by the self-monitoring function.
Analog input circuits
The analog measured variables are fed through an analog preprocessing feature (anti-
aliasing filtering) to a common analog-to-digital converter. In conjunction with the self-
monitoring function, the measuring-circuit monitoring function that is available for the
device’s general functions can detect deviations in many cases, depending on the
parameter settings for sensitivity. However, it is still necessary to test from the device
terminals in order to make sure that the analog measuring circuits are functioning
correctly.
The best way to carry out a static test of the analog input circuits is to check the primary
measured operating data using the operating data measurement function or to use a
suitable testing instrument. A “small” measured value (such as the nominal current in
the current path) and a “large” measured value (such as the nominal voltage in the
voltage path) should be used to check the measuring range of the A/D converter. This
makes it possible to check the entire control range.
The accuracy of operating data measurement is <1 %. An important factor in evaluating
device performance is long-term performance based on comparison with previous
measurements.
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