choice AC motor for propeller fan

[kingofelec]

hello
I will change an AC motor for propeller fan by another AC motor
the caracterstics of the first is :400V 50 HZ 3PHASES, 4A,2A (DELTA,Y), tr\min 690\560
power at shaft 930\350 also for delta\y connection
the caracteristic of the second AC motor:400V 50 HZ 3 PHASES 2 A 1.1A tr\min 700\500
power at shaft 530\300 also for delta\ y connection
my question:
can the second motor drive the propeller fan of the first motor?
BEST REGARDS

 

[waross]

It depends.
If the first motor is loaded over 50% then NO.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

Which by the way is highly unlikely that the motor was only running at 50% of rated load.

But IF your existing motor is connected in Wye, and you connect your new motor in Delta, it MIGHT work. Motor 1 is rated 590Nm of torque if conneqcted Wye, motor 2 is rated 530Nm or torque if connected Delta. The 11% difference might be within a "fudge factor" used by the original fan designer. The only way to know for sure would be to ask him, the possibility of which is also highly unlikely. I also feel that given that you had to ask this question, it indicates you are not familiar enough with the issues to fully comprehend the difference and know, from looking, how the motor is connected. So in short, Bill's response still stands as best, for you in this situation.

Side note:
This new(?) trend of rating motors for two power levels depending on delta or wye connection at the same voltage is something I have only just now started to encounter, and I must say it concerns me because it is confusing people. I personally don't like it, I see a lot of nuisance tripping or damaged equipment in the future. The two times I have encountered it here in the US were on Asian OEM equipment and when users went to replace the motors, the replacements were NOT reconfigurable in Wye, so they just connected them Delta and broke shafts. I don't understand the value in buying a larger motor and then connecting it to only deliver 58% of its rated torque. You are also losing a lot more in starting torque, because if connected in Star, it will only develop 33% of BDT, which means the motor can ONLY start if almost completely unloaded. I fail to see the validity of this strategy.

"Will work for (the memory of) salami"

 

[LionelHutz]

Not likely. On a little fan like that I'd expect that the first motor and the fan load were closely matched when the fan was designed so a smaller power motor will be overloaded.