Rotational Speed Controller
VE-M-011-SE
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The module is used to register the rotational speed of a varnishing turbine via a condenser microphone. The measurable speed range lies between approximately 10000 to 60000 r/min. With each rotation of the panel, an air pulse streams through an air tube to the microphone. The maximum length of the air tubes figures between 2 and 6 m with an inner diameter of 4 mm. The pressurised pressure amounts to approx. 3 bar.
Then, the microphone generates an analogue voltage depending on the rotational speed of the panel as well as on the air pressure. Moreover, the analogue signal contains perturbation components like for example noise, level break-downs due to air gap changes on the panel and low-frequency proportions due to pressure changes in the system. It is, thus, impossible to directly use the microphone signal in normal, digital sequenced actuation.
The module VE-M-001-SE utilises the microphone signal to create a signal which can easily be used, e.g. by integrating or measuring the frequency. The analogue voltage produced by the microphone is turned into a digital signal with a constant amplitude and a pulse time of about 600 ms. The frequency of the output signal is equivalent to the fundamental frequency of the analogue signal which is registered by the microphone. This module is optimised for operation speeds of about 10000 to 60000 r/min. In order to guarantee a stable acceleration of the plant, r/m’s far below 10000 can be registered most accurately, too.
The module is capable of independently aligning to the input level and it is also of compensating sudden, temporary level variations. In the initial configuration (delivery status) the input level can amount to between 2 Vss and 12 Vss, which is equivalent to a dynamic area of approximately 16 dB. The voltage needed for the operation of the microphone (phantom voltage) is produced by the module. This voltage source is so high-resistance that, even during a short circuit in the microphone, no hot spark will occur. Please note that the microphone is not included in our scope of delivery.
Via an additional input the creation of output pulses can also be blocked. The input is active-high, i. e. a 24 V level at this input blocks the output. The signal output is designed so that, in interaction with the integrated electronic fuse, it is made resistant against a short circuit. In addition to the digital signal output there is an analogue output which provides a direct voltage that is proportional to the rotational speed. Here, the output voltage amounts to 1.44 V/10,000 r/min.
The module is designed for the rail (35mm) assembly.
Application areas:
- Rotational speed registration of varnishing turbines
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