Monthly Archives: April 2011

I have a UFO

I got a used Prius 2005 hybrid some time ago and to make it more fun I have got a extra 82 Kg battery pack from Shanghai with the aim of going electric from work to home and back as a plug in hybrid.
I have so far had minimum 0.22 l/10 km consumption as the multi computer system in the vehicle only allow 48 km/h speed in electric only EV mode. Currently the BMS is on it´s way back from MI in the US and a upgrade. It is not so easy as you may think to make the multicell battery work as one unit and there are some 200 VDC 15 A and 48 VDC 50 A to play with taking care not to fry the OEM battery……

UFO

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Evaluate vibration

How do you evaluate vibration? My view is from a simplified European perspective so I try to follow a ISO standard. My favorite is the venerable ISO 10816-1 that is based on a limited shaky foundation from the 1950´s. To make it further easy to use as it was in the beforetime I look at all machines as large machines on weak foundation so it makes my need to remember numbers so limited so I can handle it.

So if a machines vibration measured according to the ISO is less than 2.8mm/s it is ok for new machine delivery and will live a long and happy life, I would likely accept 3.0-3.2 mm/s also as decimals in this area have limited value in my view.

When the machine reach formally 7.1 mm/s you should analyze and repair and get it down to around 3 mm/s depending on the machines life, cost for fix, life expectancy and time available, you may need to settle for something slightly worse.

If your machine reach 18mm/s you should avoid operation, investigation and repair is mandatory. Diesels, reciprocating compressors and hammer mills may be excluded.

Company record is currently 200mm/s on rotating machinery then you should tip toe out of the danger zone. Remember this my simplified view to make it easy, there are 10+ standards differentiating all kind of machines and a full CD when all vibration related standards are included. In my view comparing to some time proven limits give at least some guideline when machines need to be evaluated.

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Vibration start

It started as a inverse loudspeaker long time ago. My father worked at a turbine maufacturer late 1940´s and needed a tool for the mechanics to evaluate the machines status on site after overhaul. He and a companion managed to make a moving coil velocity transducer and a instrument combination. Our family have worked with machine vibrations since that time. Efforts resulted in patents at the time, find here a US I found the other day: patent

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