It should be noted that these are often times two diffrent motors from the manufactuer, and as such are not interchangable.
Before using one of the other carefully review your site conditions and code requirments for your local area. Also speak with teh applications group for the motor...
Also, be aware that when you change the base frequency you also need to look at the carrier frequency. The carrier frequency helps determine the “Sinewav-iness” of the produced power; a higher carrier gives you more square waves with which to approximate a perfect wave.
For Example:
60 Hz...
Is there any method to calculate the locked rotor current of a motor given the T-model circuit parameters?
This is an old motor and the parameters are available, but the performance data is not. I am simply trying to understand the impact of an across the line start.
Thanks,
My rule of thumb when dealing with Variable Speed applications is to not talk about horsepower. Rather I always try to keep it in terms of torque.
The old standard Equation of 5252.1*HP / RPM = Torque as a base then HP = Torque * RPM /5252.1
5252.1*200 / 3000 = 350 ft-lbs of torque.
Many...
Another possible solution would be to use a zero speed switch and have it interrupt the stop function on "t2". Consult with the motor supplier, but one of the most common "thermal withstand" times given is the "Locked rotor / Stall Time". As this is only valid during a stall, and by definition...
I would agree with Davidbeach, the magnetic fluxes would rise in the motor and you might be working the core steel into saturation.
Best advice, contact the manufacturer and they can tell you if it is acceptable and predict the performance to a fairly good accuracy. This should be a very...
Starting is very stressful on the motor. There are large magnetic forces and massive currents interacting inside the motor. Typically on larger motors the limiting factor on the number of consecutive starts is the rotor. On many smaller motors the limiting factor is the winding copper's...
Many VFD makes operate in what is called constant flux mode, meaning a constant Volts/Hz ratio. In this mode of operation the motor is a torque producing machine with the limiting factor being amperage.
In open loop operation, that is operation without any feedback from an encoder or...
I went and pulled the file, I was hoping you guys were right and I had overlooked a gearbox. The customer is wanting to do this direct coupled.
I am worried now that I might have been correct with my first impression and this motor is grossly undersized.
We have considered it, however the customer data shows a very low ineria, low enough that I feel it reflects the driven equipment alone, without any flywheel attached.
The information we are getting is that the motor should be sufficent without any sort of flywheel assistance. I am...
We are trying to size a motor for a Recip. Compressor. There is some information that is not making much sense to us. The customer wants a 500 hp motor, the compressor vendors data sheets show a BHP of 1200 hp, and an calculated HP of 500.
The torque effort curve indicated something in the...
A suggestion might be to take the compressor and accumulator to an unloaded state and have the motor-drive-compressor package load the system. As you load the system up, the amps will rise with the torque demanded of the motor. A call to the motor manafacturer may also be advised so that the...
Thank you folks, it is looking more and more likley that the TI style of thermistor has fallen out of use.
Every vendor that I have looked at appears to offer a DIN/IEC/"Seimens" style of PTC thermistor, if any at all.
I am hopeful that someone can help me out. We have an application asking for TI compatiable thermistors, 7BA is the TI part number class. I am having difficulty locating a funcutional duplicate.
TI has ceased production of these sensors, and thus far I am having no luck finding an...
In this case I believe that the PTC thermistor lead could be brought out in the same box as the main power leads. The operation of the PTC device is a very non-linear resistance response to temerature. I am unaware of any noise issues with PTC sensors.
What might be suggested is to put a...
