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Direction for Use (GB) / Gebrauchsanleitung (D)
Converter CON 011
Direction for use
1
GB
DIRECTION FOR USE
1.1 Purpose and Application
The CON 011 Signal Converter in combination with sensors of type PR 6422 ... PR 6426 of epro
Machine Monitoring Systems form eddy current measuring chains to be used for static and
dynamic distance measurements at all kinds of rotating machinery. This means that slow axial
displacements as well as fast radial vibrations of rotating machines can be measured. By using
pulse wheels or key marks sticked on the shaft, the speed of the machine can be measured and
key pulses generated.
Probes and signal converters are adjusted together and are delivered as complete measuring
chains in order to achieve a maximum accuracy. For this reason it is very important that probes
and converters always operate together. The type of the sensor and its serial number are marked
on the type plate of the converter.
The characteristics of the measuring chain are adapted to the material mainly used for
turbomachinery (reference material: 42 Cr Mo 4, according to SAE 4140). The standard
adjustment of the measuring chains is generally related to this material − if necessary, other
materials can be used for the adjustment (refer to operating manual PR 6422...PR 6426). During
installation at the machine only the distance between the head of the sensor and the measuring
target are to be adjusted. Criterion for the adjustment of the sensor is the output signal of the
converter.
The CON 011 Signal Converter is accommodated in a rugged housing, the electronic
components are completely sealed. Connection of the eddy current probe is made with a
LEMOSA connector at the front of the converter. A M20 tapped bush allows the protection of
the sensor cable by means of a cable protection tube set MPT 064/.. . Supply circuits for the eddy
current probe and the measuring electronic are contained in the converter. The nominal supply
voltage for the converter is 24V
DC
, the nominal range of the output signal −proportional to the
nominal measuring range of the sensor− may be set to either –4...−20 or –2...−18V. With the
converters for the special measuring range (CON 011 / 91x−xxx) the output voltage is firmly
adjusted to the range −4... −20V.
Five eddy current probes are at disposal. The actual type to be used depends on the measuring
range, on the available space for measuring and on the environmental temperature.
1.2 Function Principle
The measuring coil of the eddy current sensors PR 6422...PR 6426 is connected to an oscillator
circuit in the converter via a screened connection cable (see Fig 1).
The oscillator circuit generates a high frequent signal, thus resulting in a high frequent magnetic
field around the tip of the eddy current probe. If this magnetic field meets a metallic target, it
induces high frequent currents and another magnetic field which is inversely induced to the
original one. According the rule of Lenz, the induced currrent damps the oscillator signal.
The damping factor depends on the distance between sensor head and target material. The
smaller the distance to the sensor, the smaller the amplitude of the oscillator.
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