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Thanks for the input, this motor has been in operation for 37 years. It is run continuously and started only after power interuption or maintenence ~ 2 to 3 times/ year. Even though its load is much higher than NEMA standards, it accomplishes its task by being bump started by operators. It...

Some interesting and elightening points have been made. Unfortunately, I do not know the kinds of information that would be used in aolalde's equations. I know little about the rotor and stator. I don't think that the GE motors w/ longer stall times are special, they only cost $650.

GordS, unfortunately the motor is 37 years old and I do not have any documentation that states it was built for the large inertia start. It is built on a 324 frame and my thinking is that in the old days, they built them a little better with more back-iron. However, could the efficiencies of...

Yes, I am looking at a different motor. My motor - 15 Hp motor connected to a motor generator. 270 lb-ft2 flywheel connected to the shaft. Thermal overloads keep tripping on startup. Trying to evaluate bumping up the thermal overloads to 140% FLA as guided by the NEC. Yes this motor is too...

Yes, my colleagues are familiar with ~ 12 to 18 seconds. But those high numbers I posted earlier come straight from the GE motor design performance data. Stock motor, model #5KS254SAB204 hot-65.7, cold-77.3. Efficient motor, model #5KE254SAC204 hot-48, cold-54.

I think you can use.... Motor Full Load Torque = (Nameplate HP x 5520) / Nameplate RPM 1 ft-lb = 1.356 Joules (Nm) That should tell you what size motor (in Hp) to get. As for temp..... I don't know. The mfg. should be able to tell you there.

Thanks for the input. Yes, I am trying to calculate the max. inertia that the motor can turn. I have some GE 15 Hp motor data sheets which gives you all the information you need, such as max. inertia, acceleration time w/ max inertia, cold and hot stall times, and full speed/torque curves...

I see it now, thank you!

Not to deviate from Dan's question, but I have a general question about the starter being used. http://www.ssusa.cc/reference/wiring_diagrams/standard_series_drawings/series_107/107_21.pdf The purpose of the S relay and contacts? Is it for making the Delta connection for the motor windings...

I am looking for equations/methods to calculate a motor's maximum inertia. Under technical information of a motor, they might state the maximum inertia referred to the motor shaft and the acceleration time with the maximum inertia load. Thanks.

Is it a fair assumption that on average, hot and cold stall times for smaller motors (< 30 Hp) are longer than for large motors (> 150Hp)? I have data sheets for 2 newer GE motors (one is stock, other is efficient) and there hot and cold stall times are 65, 77 (stock motor) and 48, 54...

Thanks jOmega, please check your email.

The starter thermal overload tripping problem has existed for sometime (prior to 1980) which is why the operators use a jogged type of start. I believe it has existed from day one. Its difficult to determine if the original design built the motor for this purpose, and the thermal overloads...

&quot;That 324 frame motor, as you guessed is awfully beefy.... motor is overframed for some reason... suspect it either was for thermal dissipation or it has a lot of torque capability.&quot; Yes, I suspect that motor could be built to handle the torque or maybe size was picked to match shaft...

I have an old (pre-1970) 15Hp GE motor (sf-1.15, FL Rpm-1770, 550V, FLA-15Amps, Type-K, Nema Design-B, Frame-324Z, Code-G, Insul.-B) that part of a 7.5KVA motor-generator configuration. Attached to the motor end of the shaft is a 430lb. flywheel that provides 260lbs-ft2 of inertia. The...