Bat surveys at lofty heights
Wind turbine extension fore the batcorder 3
Supplied with the extension comes a special plastic disc in which the microphone is embedded in (boundary microphone). This disc was specifically developed for the batcorder. Its properties are as far as possible identical to the disc used in the above mentioned project. Thus, data collected with the batcorder extension can be compared to the project data if the batcorder uses the same settings. The disc is inserted directly into the gondola through a drill hole with a diameter of 10cm.
The extensions’s control module is responsible for controlling the power. While the batcorder is turned off (daytime) the module is connected to the power line within the nacelle (110 – 240 Volt) and charges the lead-acid gel battery. When the batcorder turns on, the module disconnects from the main power-line. batcorder and module now run on power from the lead-gel battery. The batcorder is galvanically isolated from the power line to eliminate noise induced from the power-line. If the main power of the nacelle is switched off, the batcorder still can run for a couple of nights on the lead-gel battery (UPS function).
Just before sampling is stopped, the control module sends a status message per SMS to any selected cell phone number. That way you always stay informed on recording count, memory status and other information. If possible it also reports problems with the power supply. This feature requires that you install a SIM card for dialing into your cell phone carriers network. you’ll need a connection to a cell phone network to use the feature.
Fundamental considerations for acoustic monitoring on WPUs
The nacelle of a wind power unit (WPU) is basically a suboptimal location for acoustic sampling. Extreme weather conditions put a lot of strain on the microphone and may lead to loss of sensitivity. Strong electromagnetic fields and acoustic noises may temporarily exist and lead to large numbers of erroneous recordings without bat activity.
Monitoring for a prolonged period of more than one year, as demanded by some authorities, is not possible to do with todays technologies without regular service of the used devices. For example can microphone or device be damaged by strong frost.
The type of the wind turbine and as well as the placement of the batcorder within the nacelle have an influence on the amount of interferences. In most type of WPUs the batcorder can be used without problems. Some older WPUs seem not to be as optimal as new systems. We recommend to schedule a talk to technicians of the producer of the WPU to allow for special adaptions etc. Maybe test runs will be necessary in addition.
See also our collection of tips and tricks for nacelle monitoring.
Installation and usage
For the installation of batcorder and wind turbine extension you’ll need certified technicians of the turbine producer or operator. Thus we recommend you pan the installation schedule early. Apart from giving general tips on how to setup the batcorder we can not do the installation for you.
The batcorder with wind turbine kit was installed on a multitude of different windturbines, altogether more than 500 installations. Most of them were in Germany, but some were installed in Denmark, Netherlands, France, Austria, Switzerland and the UK. So the range of different turbine types is rather large and with a few exceptions installation and usage went smoothly. We have learned that there will be turbine individuals that produce no noise, some produce noise sometimes. Yet, it is very hard to link to a single type, thus we can’t give any recommendations.
Some turbines mainly of Senvion and GE produce rare voltage peaks on the main power line. These peaks can damage the batcorder power supply. We recommend to ask for a filter unit to be connected between power line and batcorder power supply to avoid unnecessary climbs to the nacelle.
Each wind turbine extension includes a control module (power and SMS control), a microphone disc with calibrated microphone, installation accessory as well as cables.
- control module
- support rail and material for attachment (special kits for aluminum as well as GRP)
- microphone disc incl. calibrated microphone
You’ll need in addition:
- batcorder 2.0/3.0
- SIM card for sending SMS messages (Prerequisite for the this feature is that you have a carrier network available at the turbine location.)