Produkt-Neuheit

Alternative energy and noise protection – News from Gefell for wind turbine noise measuring

The improved Boundary-Layer Microphone - GF 1 and the weatherproof power supply unit WN 1

The Boundary-Layer Microphone GF 1 is a new measuring equipment especially designed to record sound emissions at Wind Power Stations according to IEC/EN 61400-11.

The boundary GF 1 and the weatherproof power supply unit WN 1 are specifically developed extensions in order to record the sound emission of wind power stations with measuring microphones.

Additionally, the GF 1 is suitable for determining emission-relevant sound power levels in open spaces, e.g. measurements at power stations, construction sites, filtration and cooling plants among others.

Due to the Operation near the ground, unwanted influences on the measurement results by reflections from the ground are avoided. Measurements are largely independent of the position of measurement and the composition of the ground.

The lower wind speed near the ground causes a further reduction in wind-generated noise at the microphone.

Acoustical specifications

Together with the impregnated secondary windscreen, the primary windscreen of the GF 1 ensures a broadband reduction of the induced wind noise at the microphone by 40 dB.

Due to the acoustic effect of the sound-reflecting boundary layer, the microphone sensitivity increases by 6 dB as inherent to its functional principle. Thus, an overall improvement of the signal-to-noise ratio of approx. 46 dB can be achieved.

As measuring microphone element, class 1 measuring microphones are suitable, which consist of measuring microphone cartridges with a frequency range from 20 Hz to a minimum of 10 kHz, a dehumidifier adaptor and a measuring microphone preamplifier with 200 V or IEPE supply.

Electrical specifications

The WN1 is a weatherproof power supply unit with the measuring microphone power supply unit MN 921.

It provides an operating voltage for conventional measuring microphones (7-pin LEMO®) as well as for IEPE measuring microphones. It can be operated with accumulators, batteries or mains voltage.

The amplification of the microphone signal can be set using a rotary switch.

The integrated line driver allows a transmission of the microphone signals over a cable length sufficient for measurements on wind power stations.

Mechanical specifications

The structural design of the GF 1 allows a simple calibration with a sound calibrator.

With the divisible ground plate and the secondary windscreen reduced to an optimum for function and handling, transportation in a compact transport case is possible.

With the impregnated secondary windscreen, the ground plate coated with varnish and the weatherproof power supply unit, GF 1 and WN 1 form a weatherproof system for the standard-conforming sound emission measurement of wind power stations.