A flywheel?
Since you will be accelerating faster than gravity you would not need to release only at the bottom of stroke. I was thinking of a punch press design. You may need the ram to quickly reverse stroke and get out of the way of any bounce. Have the down stroke of the ram trigger a...
I was hoping that with the low duty cycle would it not be a problem at all. But I have absolutely no real world experience running a TEFC motor without a fan. There should be room enough to mount an external fan if needed.
Barry1961
The 1/4 hp will be deenergized while the creep motor is running. The creep motor will be deenergized and disengaged, with clutch, when the 1/4 hp is running.
Thanks all!!
Barry1961
I have a .25 hp, 750:1, TEFC integral gearmotor that I want to drive very slowly by removing the fan and coupling to the stub shaft. It would be driven about 6 rpm with another very small integral gearmotor through a small clutch. A basic creep drive.
The actual required horsepower at high...
ozmosis
In past applications I did not have much luck generating torque quickly in V/F mode. In a recent application with a Mitsubishi E700 it took about .5 second to reach 100% FLT in V/F mode. I tried raising the voltage boost with not much effect. The way I got torque quickly was in...
Brother lists the max brake cycles at 10 per minute. From what I understand this is due to the brake coil getting hot from the high inrush. I don't know how much a light spring would improve the rating. Maybe a light spring and a resistor?
I have done my best to convince the customer not to...
Sorry about not putting the VFD in the OP.
It is an AB PowerFlex and a Brother gear motor. Brother and Sumitomo both make very strong high reduction, high efficiency gearboxes down to 1/50th hp in 3 ph. They are just single voltage at 1/50th, 230 V or 460 V. I have used these on several...
It is a vector drive, they are just worried about drift. I don't think they will need it but they like the idea of the rotor being locked in place after decel. There is no feedback now and they don't want to add any.
Barry1961
I really hate to say this but I am not sure how to accurately measure the DC current. I would guess the VFD is still using the same carrier frequency and just turning off most of the IGBTs to get the DC so I need a RMS reading. Will the winding act as a good enough filter to allow a accurate...
A customer has a small high cycle indexing conveyor with a 1.3 second cycle. Almost all the braking with be done with decel but they are thinking of using DC injection braking to insure the motor comes to a complete stop. This is a 1/50th hp, 3 ph motor on a 300:1 high efficiency gearbox...
With the tests done so far the final ratio should be around 240:1 which would more than double the reduction. The load has a fair amount of inertia to overcome during start up so the peak motor torque should drop even more since reflected inertia is divided by the square of the ratio.
The cost...
The customer was able to get some support from WEG at last.
The WEG was displaying amps and not percentage. But the WEG guy says go by the percent torque in sensorless vector mode and it should be within 2-3%.
The readings from sensorless vector percent torque seem to be about what I expected...
I was told from another source that if I put the VFD in vector mode and read the percent torque parameter it should be fairly accurate even at low hertz. The VFD self tuning would compensate for hertz and voltage variations.
He also said you would need to know the VFD output voltage...
They are running the motor at 25 hertz now which is the speed they need to run for the application. This is a 4 pole 1769 rpm motor so the motor rpm is going to be close to 725 rpm at 25 hertz.
The motor is running cold, at ambient.
Barry1961
