Measurement transmitter

摘要

A measurement transmitter for providing a measured value to a control system, comprising: a sensor having a transducer for outputting a primary signal dependent on the measured value; a first electronic circuit for processing the primary signal to an intermediate signal; a second electronic circuit for processing the intermediate signal to a signal representing the measured value, wherein the second electronic circuit has a signal output for outputting the signal to connection lines; a housing arrangement having a metal material, wherein the first electronic circuit has at least a first circuit carrier, and the second electronic circuit has at least a second circuit carrier, and wherein the first and second electronic circuits are positioned in the housing arrangement spaced from one another. Electrically conducting shielding and high frequency filters for protecting against HF disturbances, which can get into the housing arrangement via the connection lines. The electrically conducting shielding and the high frequency filters are arranged between the first and second circuit carriers.

主权项

1. A measurement transmitter for providing a measured value of at least one measured variable to a control system, comprising:
a sensor having an electrical transducer for outputting a primary signal dependent on the current value of the measured variable; a first electronic circuit for driving said transducer, for processing the primary signal and for outputting an intermediate signal dependent on the primary signal; a second electronic circuit for feeding said first electronic circuit and for processing the intermediate signal for producing a signal representing the measured value of the measured variable, said second electronic circuit has a signal output for outputting the signal to connection lines; a housing arrangement, which has at least one electrically conducting material, especially a metal material, said first electronic circuit has at least a first circuit carrier, and said second electronic circuit has at least a second circuit carrier, said first and second electronic circuits are positioned in said housing arrangement spaced from one another; and an electrically conducting shielding and high frequency filters for protecting against HF disturbances, which can get into said housing arrangement via the connection lines, wherein: said electrically conducting shielding and said high frequency filters are arranged between said first circuit carrier and said second circuit carrier; said shielding includes an electrically insulating shield support having a metal shield layer; said high frequency filter is separated by the shield layer from the second electronic circuit, said shield support includes at least one via, by way of which said second electronic circuit is connected with said first electronic circuit; at least one of the electrical vias is galvanically isolated from said metal shield layer and annularly surrounded by said metal shield layer; the capacitance between said via and the shielding amounts to no more than 1 nf; said at least one high frequency filter is arranged on said shield support; said first electronic circuit is connected with said electrical via by way of said high frequency filter; the separation of said high frequency filter from said via amounts to no more than 1 cm; said shielding includes at least one electrically conducting annular sleeve shaped electrode, which surrounds said at least one electrical via, is galvanically isolated from said via and in galvanic contact with said shield layer; said sleeve shaped electrode is embedded in said shield support; and the radius of said sleeve shaped electrode is so selected that the capacitance between the annular electrode and the conductor of the via is compatible with the ignition protection type “intrinsically safe” (Ex i); said metal shield layer is in galvanic contact with the electrically conducting material of said housing; said housing arrangement and said shield layer form a Faraday cage around said first electronic circuit; and said shield support is a separate, plate shaped component, which is installed in said housing arrangement.