Mechanical Load Modelling

[bhalfweeg]

I am in the process of developing a preliminary power system model for a new oil platform using the power system analysis package ERACS. As part of this model I'm looking to perform motor starting studies, which will require me to model the mechanical loads being driven by motors. Can anyone assist me with typical mechanical loads, eg:

LV pumps, fans
MV pumps
oil export pump ~5 MW
gas compressors ~1.5-2.0 MW
water injection pumps ~5 MW

Specifically I am looking for typical load inertia and torque characteristics (constant, proportional to speed, etc.).

Any assistance would be appreciated.

Brendan

 

[electricpete]

For centrifugal pumps and fans, the torque is approx proportional to speed squared. (Not much help I'm sure).

 

[Alex68]

I'm sorry but your request is too vague. There are a lot of parameters
Some indications:
- LV & MV pumps: the load inertia is <= motor inertia. the motor inertia depends on the motor power and poles number. torque is proportional to speed squared

- fans: typically low speed and big inertia (>motor inertia)

- big load: in this case the torque curves can vary from the starting condition to the full load condition. usually they start with valves opened to reach the full speed with low load, after the valves are closed and the torque increase.

- compressor: if it is a screw compressor then its inertia is negligible respect the motor J. the torque could be constant.

Suggestion: you may ask to some manufacturers

 

[bhalfweeg]

Alex,

Thanks for your reply, I realise my query is quite vague, unfortunately I'm in the position that I can't approach vendors for commercial reasons. My colleagues in the mechanical group are going through vendor pre-qualification at the moment. The European Union rules on fair competition really get in the way of getting vendor assistance during front-end engineering.

regards,

Brendan

 

[jOmega]

Appreciating the commercial situation you describe, it might be worth considering contacing a university or technical school that has a Mechanical Engineer ing Department... You might possibly be able to obtain the technical assistance your seek using them as a &quot;consultant&quot;. This then would eliminate the commercial mine field.

 

[jbartos]

Suggestion: Visit

http://www.rexroth.com/riq/2000/riq.2000-3/en/article12.pdf

http://www.selinc.com/techpprs/6023.pdf

http://www.mastercontrols.com/ProdInfo/Catalogs/ECat08a.htm

http://www.maxma.com.tw/ht.html

etc. for more info
Try manufacturers' literature consisting of catalogs, application notes, data sheets, etc.
Also, you may send emails to tech supports. Tech support does not deal with any sales issues.