Monthly Archives: April 2011
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……
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.
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