# Altistart 48 Settings



## John Valdes (May 17, 2007)

No one can answer the question until we know exactly how you use your machine. How mnay times an hour are you hammering? That kind of info.
If I were in your shoes, I would get your vendor involved. The people you got the soft start from.
Let them make the calls as this is a brand new application.
They sold you the SS. Let them tell you how to set it up.


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## Forge Boyz (Nov 7, 2014)

Ok for clarification, it's not my machine, I'm connecting it. I don't have the exact size on the mill but it has a drum that that is about 30" long and about 10" in diameter with the hammers extended. Im sure I can get it running, it's just I was looking for the best way to set up the starter for efficiency and longevity. This will get started and run to grind about 50 ton of grain and then shut off. The mill goes through at least 100 ton of ground grain a day so it will be run every day 

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## paulengr (Oct 8, 2017)

There are essentially two ways to approach soft starting. If the reason for soft starting is to limit the torque output and you have more available torque out of the motor than the load can handle so we're trying to start slowly, then you go with longer ramp times and voltage control. This is for whatever reason kind of the "assumed" approach in all soft starts. If you try to do this though with a high inertia load such as a hammer mill, quite often what happens is that the thing barely even tries to turn and you complete the ramp well before it gets up to full speed so the current draw gets up there close to 600% anyways. So you're not really soft starting anymore, just screwing around with the voltage during startup. In fact for most soft starting applications this isn't what anyone is trying to do so even though it's kind of the default in the software, it's not what you want.

The other situation is where you need to limit the output current or torque for some reason such as running off a relatively soft bus (like running off a generator) or current is limited by some excessively tight protection or because you don't want to break a shaft, or they just want to make the motors and the rest of the power train last longer, or some other sort of mechanical torque limit. In this case the goal is to start as quickly as possible but limit the torque/current during starting. So if you HAVE to put in a ramp time, put in something really short like 3-5 seconds. But if like with the Benshaw MX2/3 controllers you can simply pick current limiting mode and ignore that silly voltage ramping stuff, that's what you want. The current limit is where you have to make some judgement calls. Compressors for instance run pretty good current limiting at 350% but with crushers, hammer mills, and other really high inertia equipment sometimes you have to go all the way to 500% current limit...a point where basically it's more of a "slightly softened" soft starter...not too far from outright ATL starting at 600%. And that's where you are at. You will find that at around 200-300%, the start times will get crazy long (like 30-90 seconds). So this seems OK, right? Think again...the motor sits there accelerating so slowly that it overheats and trips the overload protection. Usually the first response from rookies of course to avoid overheating is to increase the ramp time to get the current down. Well this just makes the already bad situation worse unless you eventually get to the point of ramping so slowly that the motor never really gets above FLA during acceleration, if the soft start doesn't become thermally limited (on the bypass contactor variety) and trips out due to overheating of the soft start instead of the motor. The correct response to an overload problem is actually just the opposite...crank the current limit up higher. As long as you don't exceed any real "hard" limits on current, this reduces acceleration time dramatically and gets you started without tripping the overload protection.

So what happens in this type of setup is that at first the controller starts ramping up the voltage quickly. But pretty quickly the current is going to reach the current limit. At that point the controller stops ramping the voltage and simply controls voltage to maintain the target current limit. Eventually when it gets up to speed the voltage eventually makes it to 100% and then the current drops as the motor comes up to full speed (making the FLA target) and the bypass contactor closes in.

Watch out for soft start default overload settings, too. They are factory defaulted to crazy low settings from ALL manufacturers. The NEMA standard (and IEC AC4 standard) is overload class 20, NOT 10. That sets the curve. Class 10 is a special class reserved for very special situations with very low loads where it is hard to detect an overload such as submersible motors. And both NEMA and IEC overloads are actually set to 115% of FLA by specification. That was originally done so that thermal-mechanical overloads (eutectic or bimetallic) had a wide enough tolerance to work. But later if someone substituted an electronic overload relay for the original thermal-mechanical device, it would suddenly start tripping with marginal processes. With a 1.15 service factor on the motor you can run there all day without damage, so go ahead and use the 115% of FLA setting for the overload. That will duplicate what the standards call for when it comes to overloads. HOWEVER you mentioned a hammer mill. Check the existing overload relay and/or the motor very carefully. Crusher duty motors specifically call for a Class 30 overload (higher thermal tolerance) to deal with the high starting inertia.

If you get frustrated and you're in the Southeast PM me. I'm a factory authorized service technician for Schneider drives.


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## paulengr (Oct 8, 2017)

There are kind of "standard" settings for both VFD's and soft starts depending on the application that work pretty good without needing an engineer to figure it all out.


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## Forge Boyz (Nov 7, 2014)

paulengr said:


> There are kind of "standard" settings for both VFD's and soft starts depending on the application that work pretty good without needing an engineer to figure it all out.


And this is what I'm looking for. The altistart 48 has as its default starting profile where you set the initial torque as a percentage. Is this the same concept as current limiting? Default is 20%, which seems low.

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## paulengr (Oct 8, 2017)

Forge Boyz said:


> And this is what I'm looking for. The altistart 48 has as its default starting profile where you set the initial torque as a percentage. Is this the same concept as current limiting? Default is 20%, which seems low.
> 
> Sent from my XT1585 using Tapatalk




They are doing that in VFDs and soft starts. Depends on what “application profile” means. For a hammer mill I would start at 70%. It’s just a starting “ramp” until you current limit which with a hammer mill is just getting it rolling and not much else. 20% is where you start on a pump application and the goal is to avoid slamming or water hammer or big fans where they are high inertia but long startup at low torque is ok. Pedal to the metal for hammer mills.


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