Laboratory ventilation - dual motor fans

[tudogs]

Hi all,

Does anyone know where I can find information, GA drawings etc for a dual motor (duty/standby) centrifugal fan (SWSI & DWDI)with a nexen disc brake system. The consultant has specified this arrangement however fan suppliers in Australia do not appear to have experience with the arrangement. The intent of the arrangement is that should a belt/motor/bearing fail then the duty motor will be de-energised and the standby motor will start. The consultant says that failure can be sensed by the variable speed drive for the duty motor and initiate an auto changeover to the standby motor. The brake system will initiate on standby motor failure and a backup fan (same arrangement) will take over.

 

[imok2]

I suggest you contact these people and discuss your particular problem.

http://fantech.com/pages/cent_desc....6&Product=SWSI & DWDI Fans - Centrifugal Fans

 

[SAK9]

I am yet to hear about the technology suggested by your consultant which allows the Variable Speed Drive to detect belt and bearing failures!

I have seen AHU fans with dual motors with belt drives.THe idle motor also will be in rotation and I remember an electrical engineer mentioning about an anti EMF protection in the idle motor circuit to prevent the buildup of back EMF

 

[ozmosis]

SAK9
Belt failure detection is available within a VSD. I'm product manager for the Siemens range of HVAC drives (

http://www.sbt.siemens.com/HVP/Components/products/variablefrequencydrives/default.asp)

and we have built-in a 'sensorless belt failure detection' that you set up to monitor a torque level with hysterisis and if the load drops below this range (you have 3 points within the speed range you set up)the drive trips or alarms. The 'belt failure detection with a sensor' takes a pulse input from the belt and feeds directly back to the VSD with the number of pulses. When the pulses stop and the drive is still in a RUN command, the assumption is that the belt has broken. For bearing failure then it is the other other way round and measuring overload in the motor. However, a bearing failure is usually heard before it is measured. I think also Danfoss have this feature too within their range of drives and I'm sure the functionality is probably available in others although they may not actually call it 'belt-failure detection'.

 

[tudogs]

Thanks for the information. Much appreciated