Fluid Coupling Replacement

If the fluid coupling serves solely as an equipment starting device, and if the soft starter characteristics match those of the load, I would think so. However, if the fluid coupling serves to keep load shocks from affecting the motor, a soft starter might not help. (Tentative opinion--just some things to think about.)

The start up load is usually low, normally around 45-amps. The piece of plant in question is a Animal Feed Drier and is loaded slowly until it runs at maximum amps usually around 85-90 amps. It doesn't get any shock loads. The amps always come up slowly over 90 mins.

The only problem we would have is when we have a power outage and it has to be restarted with a full load.

you can, but a fluid drive is much better than a soft starter in terms of maintenance and a fluid drive is more convinient on big units.

Depending on what you are driving,I suggest you look at powder couplings, They give a controlled start and where the need arises (ie for long conveyors)you can use two,three or four motors in series,we used these drives on overhead conveyors that were over a mile long & there was never any "hunting" on startup, anyway worth looking at.

Bazzer.

My experience with fluid couplings is also very good. Very simple device, requires nil maintenance and reliable. We have used them in long travel motion of the cranes.

We've had good success with soft starters. From the amperage you are talking about, it doesn't sound like much more than 75 hp or so. (Unless you are talking 2300 volt motors..!)

I'd look at a couple of things, though--

1. Do you have electrical help in the plant that won't take one look at a soft start and crawl under the nearest desk to suck their thumb?

2. Our experience with soft starts has most been with no-load, high inertia starting, although every once in a while we have a chipper jam up and the soft start gets punished when the guys are cleaning it out and trying to restart before the machine is fully cleared. I have not heard of any woes from this, though. We do watch the sizing--300% + of motor full load current. You would have to talk with your soft start supplier about full load starting.

3. You may be faced with buying a spare soft start if it is the first application in your plant and you cannot stand any downtime if the soft start calves. On the other hand, you may already have a spare fluid coupling in stock.

One other thing you might consider--this is a small enough drive that a variable frequency vector drive might do the same job as a soft start with benefits of variable speed, IF that is of any value to your process.

Good luck and let us know what you decide!

Jon

In case of Fluid coupling starting, the motor is almost started in NO-LOAD condition at full/ rated voltage application; also in NO-LOAD condition starting torque requirement is less, The load (driven mechanism) is coupled with motor when the motor is attained its rated speed and load torque requirement is deliverd by the motor.

In case of SOFT STATER starting,the initial torque developed by the motor is very less due applied voltage across the motor terminal is very minimal. So initialiy the motor may not drive the driven mechanism if selection of stater rating is incorrect and due to drawal of high current, the soft stater may get damage.