Feeds:
Færslur
Athugasemdir

Posts Tagged ‘AKG 411’

IMG_2200

I have spent 40 years of my life as an electrician at the same workplace at Eimskip and have seen incredible changes in the development of various equipment and devices.
I remember electric forklifts where the speed control was just a few huge resistors and  sparking DC contacts. Then came forklifts with Triac controllers, then FET controllers, and most recently computer-controlled with three-phase speed controllers.
I have seen the same in the development of harbor cranes. The oldest ones with 32T lifting capacity and Ward Leonard DC controls, where „feedback or drop“ energy is wasted in heat in large resistors.
But today, all harbor cranes are computer controlled, with lifting capacity up to 125T, three-phase motors and some return the feedback energy into the electricity grid.
During the years I have recorded the crane at Eimskip and some of them have found its way into this blog.
In most of these cranes, which are driven by electricity, almost nothing can be heard other than a loud fan noise. In the oldest crane, you can also hear repeatedly clapping relays, large DC contacts and spark pops, which have been sound for 40 years. You can also hear the difference and feel the pain when the crane is struggling with heavy load.
From the latest cranes, you can hear a high-frequency „song“ from the coil in the motors, similar to tweeter in speakers, which changes little or nothing at different loads.
It has therefore been tempting me for quite some time to record these motors with Geophone and contact microphones so other noise in the crane could not be heard.
But after doing some experiments with contact microphones in this modern cranes, I found out that I can spend many hours recording all kinds of sounds there.
Here are the sounds in hoist motors in the two new cranes.
In both cases, the cranes are loading containers to ship
It was recorded simultaneously with two contact microphones and two Geophones in four channels.
First comes the Liebherr CTC crane P148L (WS)- Super with two 400Kw motors with a registered 70t lifting capacity under hook beam.
  mp3 256kbps / 11,4Mb

Then comes the Konecranes Gottwald ESP ,8 with one 290 kW motor and lifting capacity up to 125 tons. Because of the compact design of the motor, gearbox and rope drum, this recording include the sound in the gearbox which have internal brake. 
  mp3 265kbps / 11,4Mb

Recorder: Sound Devices MixPre6
Mics: AKG 411 PP & LOM Geophones
Pix: Samsung S22 (see more pictures and spectrogram)

Location:  64.150394, -21.846315

Read Full Post »