# Soft start of high/low inertia load



## MDShunk (Jan 7, 2007)

Not even sure I understand the question. If your soft start isn't starting the load "softly", set the accel time higher. lain: Starting a trim waste blower should be among the easiest soft start jobs I can think of.


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## gpop (May 14, 2018)

Some soft starts can be set to start in a set period of time other will current limit the start up. As you have a blower there not much load until the rpm has built up.

Depending on the blower design one will have a high load near peak rpm until the pipe work starts to cause back pressure then the load will begin to drop. The other type will have peak load when the pipe work becomes pressurized. Either way from the eye site point of view if you have a current limiting soft start it will look like the blower spun up really fast.

Do as MD says and try to set the softstart to be as soft as possible but realize that you are doing it for looks rather than for the protection of the electrical system.


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## micromind (Aug 11, 2007)

It could be configured wrong. 

Most soft-starts can be configured for constant current or voltage ramp. 

Which one to use depends on the type of load. 

For example, constant current doesn't work with a lineshaft pump because the 'springing' of the long shaft will make it unstable but voltage ramp will accelerate it smoothly.


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## Signode (Oct 9, 2016)

This is a cheaper soft starter in which just system controls just two phases; one is direct. It just has;


First pot for start time adj
Second pot for initial voltage adj
Third pot for stop time
No any other setting available. 

One more problem with using this soft starter is tripping of thermal overload. As the start time of waste blower is almost >= 9sec, so regular thermal overload doesnt work here because starting current goes >=260A (30kw motor) and then gradually decreases but during this period, overload gets trip. So we had to use electronic overload which has larger starting time setting available.


Is there other soft starter available which ramps up the voltage rather starts direct from 230V?


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## gpop (May 14, 2018)

Does the soft start have the boost option that you hard wire?

If so you may be able to use the boost at a lower starting voltage.


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## gpop (May 14, 2018)

I can see that you have other posts on the same problem after adding overloads. I was wondering did you add them before the soft start or after the soft start. (manual says before soft start)

Im trying to figure out in my head if it matters as i have never had a problem that lead to me testing input and output amps. 

I know on a vfd you can measure higher amps on the output than you measure on the input at lower hertz as it drops the voltage to reduce heat in the winding's which makes sense but that has capacitors. 

No idea about a soft start especially as a amp meter probably couldn't read it. (at half voltage the gates would be off the same amount of time that they are on so what would the amp meter think of it)

I haven't installed any modern soft starts for years as we went to vfd's as it was cheaper to use them than to add a soft start to stock. The last ones i did install were smaller versions of the one you are using and we have never had a problem with them.


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## paulengr (Oct 8, 2017)

I do soft start installs all the time.

The Square D Altistarts arent bad. The older line was not good. Benshaw is top of the line out of everybody. Saftronics (Opal) isn't bad either but don't expect much customer support. Motortronics can be trouble at times so stay away. Allen Bradley has no clue what they're doing and you can't adjust much, and run, don't walk away from anybody that attempts to soft start on two legs only so that throws ABB out even if it's the more sophisticated three legged one.

Not sure why you would want or tryst an external overload. Microprocessor overload algorithms are vastly more reliable and accurate, are not affected by ambient temperature differences, and save electricity since they don't have or need heaters. I'd dump that thing with the soft start install.

First, recognize flux is the magnetic field in the motor, proportional to voltage, purely inductive, and constant for a given voltage. Its a loss but you have to have flux to make a motor work, except permanent magnet motors. At full speed its about 5-15% of total amps. Torque is almost pure resistive and the rest of the amps. So at a first pass torque is close to proportional to amps and somewhat with voltage too but with voltage control, it is no longer mostly independent of the load.

Soft starts have current limit and voltage control as your options. A few have torque control but I've never used it. In voltage control mode torque does whatever it does to ramp and motors can jump pretty hard even at low voltage. In torque limiting (control) mode, acceleration is usually pretty constant with high inertia loads which are almost always also constant torque independent of speed. Fans and pumps are variable torque and more suited to voltage ramping unless it's high inertia. If you have a load that has a breakaway torque, that's what boost is for. Otherwise leave it off. Most industrial loads have bearings so it is rarely needed.

As far as starting based on the description I would aim for 350% current limit to start with a 70% initial voltage. Go up or down on the current limit as needed. If it jerks too much go down in 50% increments. If it's too slow go up in 50% increments until starting is acceptable. Overload is a problem on all high inertia loads. Use the soft start's overload. Usually the factory default is class 10 which is way too low and on purpose so you set it correctly, except with crappy IEC motors that are way under designed thermally to achieve European EC4 and EC5 efficiency initiatives. NEMA motors are rated to run at 200% of FLA for 2 minutes and default to class 20. If you know the motor is designed for it (crusher duty) jack it up to class 30. That will be on the name plate. That's on starting. Most soft starts let you have different ratings for starting and running, but be careful if you do this to always cold start or you'll burn up the motor. Alternatively use thermal switches or RTDs which gives much better motor protection since it directly measures temperatures, input to an enable function on the soft start, and turn off the overload function.

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## Signode (Oct 9, 2016)

gpop said:


> Does the soft start have the boost option that you hard wire?
> 
> If so you may be able to use the boost at a lower starting voltage.



No. It doesnt have. Neither BOOST option nor electronic built-in overload.


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## just the cowboy (Sep 4, 2013)

If you want to save money don't buy cheap. The problems that you have posted in this and others, repeat that point. Talk them into less improvements, with better equipment. If you do this projects will go smoother and you will end up getting more money down the line. If you keep buying the cheaper ones they will stop approving projects because of problems at startup like this one.


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## gpop (May 14, 2018)

So im guessing the overloads you installed are after the softstart


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## JRaef (Mar 23, 2009)

If it is a squirrel cage blower, as most trim waste blowers I have seen are, you likely cannot accelerate it with a cheap soft starter like that unless you have air dampers that can be closed off during starting. In centrifugal blowers, flow = load, so closing the dampers *removes *the load.


If there are no dampers and the blower is immediately pushing air then it will never start with that cheap little soft starter. As mentioned, it only controls 2 of the 3 phases, which creates a thermal strain on the motor because it creates what are called "negative sequence currents" in the rotor that fight the torque being created. So the motor is essentially robbed of accelerating torque, but the heat created, especially in the rotor, is the same. The result is, you have to turn up the torque settings, which runs the risk of exceeding the thermal damage curves and the unit trips on OL before it can accelerate it fully.


Your only chance is that you must replace that piece of junk with a REAL soft starter with 6 SCRs, one that has Current Limit starting as an option and that is capable of at least 450% current for 30 seconds. Over size the soft starter if you can't find one with those specs. Then set the starter at 350% current limit with _*zero ramp time*_, so the starter goes into current limit immediately without ramping and wasting thermal time. If it doesn't accelerate, shut it down, wait an hour for the motor to cool off, then try it again at 400% CL. If it still doesn't start, wait again and try at 450%, it will work there, but you want to see if it will start at a lower value first.


The other alternative is to use a VFD...


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## gpop (May 14, 2018)

What do you want the motor to do. It seems you have a idea of what you think a soft start of a motor should look like and a reason why you want it to look that way. 

It seems you want a controlled ramp start which is vfd territory the why is still a interesting question.


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## frenchelectrican (Mar 15, 2007)

I been reading along this and If that is squirrel cage blower type and a large one and I would ditch the soft start and go with VSD and add a damper to close the intake to get it up running speed quicker and once you have it running you can leave on vsd or bypassed mode. 

As other pointed out pretty clear the cheap soft start only work on two phase sorta like open delta starting which it is HARD on motor especially with high intera loads. unbalanced current will overheat the motor pretty fast especially in starting mode. 

I would stay with wye-delta starting system or autotransformer starting system. very dependable and less thing can go wrong.


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## Signode (Oct 9, 2016)

The motor is regular squarl cage induction motor and blower dont have damper. 

SO finally, i would have to move to that soft starter which should have 6SCRs. I did not ever use soft starter; always used VFDs. Thats why i trapped.


YES. I was expecting the operation of soft starter as SOFT START the motor but here is inverse. 

Let me ask to Schneider for required one. It will be better if any experienced member guide me the correct model which he has already used.


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## JRaef (Mar 23, 2009)

Signode said:


> The motor is regular squarl cage induction motor and blower dont have damper.
> 
> SO finally, i would have to move to that soft starter which should have 6SCRs. I did not ever use soft starter; always used VFDs. Thats why i trapped.
> 
> ...


ATS48, but I would over size it by at lease one size up.


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## frenchelectrican (Mar 15, 2007)

JRaef said:


> ATS48, but I would over size it by at lease one size up.


^^

That what is the best answer and I agree with him to get oversized due long starting ramp.


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## gpop (May 14, 2018)

The op seems upset that the motor is pulling 260 amps at reduced voltage during starting which is around 400%

I dont think any soft start will do what he wants.

From his posts it looks like he wants to ramp at fla for some reason.


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## Signode (Oct 9, 2016)

gpop said:


> From his posts it looks like he wants to ramp at fla for some reason.



Yes, you are right. I am sorry i dont have experience in soft starters. Kindly guide me is there any soft starter available which ramps up the voltage rather start from 230V and then switch to 400V which reduces the life of belts?


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## frenchelectrican (Mar 15, 2007)

Signode said:


> Yes, you are right. I am sorry i dont have experience in soft starters. Kindly guide me is there any soft starter available which ramps up the voltage rather start from 230V and then switch to 400V which reduces the life of belts?


How long the load to get up to the running speed ? 

and I would use 400 volt supply instead of 230 volts due most soft start the voltage level will be way too low due the V/HZ ratio is lousy that why ya getting the motor hot pretty quick. 

And ya on 50 HZ or 60 HZ source ?


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## Signode (Oct 9, 2016)

frenchelectrican said:


> How long the load to get up to the running speed ?
> 
> And ya on 50 HZ or 60 HZ source ?


>= 9sec.


We have 3phase 400V 50HZ distribution system.


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## paulengr (Oct 8, 2017)

frenchelectrican said:


> How long the load to get up to the running speed ?
> 
> and I would use 400 volt supply instead of 230 volts due most soft start the voltage level will be way too low due the V/HZ ratio is lousy that why ya getting the motor hot pretty quick.
> 
> And ya on 50 HZ or 60 HZ source ?


V/Hz has nothing to do with it unless you're running a dual voltage motor in the wrong configuration (High voltage configuration but running at low voltage). Overloaded is overloaded.

A soft start is effectively a three phase lamp dimmer, nothing more or less. It cannot do voltage doubling. Whatever your line voltage and frequency is, that's what you get.

Reduced voltage means four things. This would seem like it would help high inertia loads in terms of overheating during starting, Since energy is power times time and power is torque times RPM assuming it takes the same energy to get the motor up to speed lowering torque increases time so no change in energy (heat) theoretically but in practice I find overloads trip easier the longer you take to get up to speed so soft starts don't necessarily help unless you do something like set the maximum current to say FLA during starting. In general with high inertia loads I set a high starting voltage just to get into current limiting mode and then do current limiting starting all the way up. Voltage mode is best for fans and pumps that have a variable torque curve so we're just following the load curve without current limiting. And on loads that are almost constant or very high like conveyors, soft starts are almost useless because they reduce or control torque on starting. At this point often the only benefit is to minimize breaking shafts when you hit the 250-300% peak torque out of an across the line start.

Second reduced voltage means current is reduced to a controlled level. If you have issues with the service size of your incoming line it makes a major difference. For instance when operating on a generator or if the transformer is getting near capacity, you can cut the peak current during starting. It's not uncommon to set up remote pump stations to current limit at say 300% of FLA so that with a duplex pumping station the generator peak output is only 200% of the normal load instead of 350% of the normal load, usually a huge cost savings.

Third reduced voltage means you can "inch" or jig/creep for machine positioning without the extra expense if a full VFD if you just need this occasionally for work positioning or maintenance. It's not a full time speed reduction or controlled but it can be useful.

Fourth it means lots of electrical noise. Ever turn your lamp dimmer way down and hear the la,p filaments chatter? Ultimately you don't want to run reduced voltage fir very long. The goofy chopped waveform eats efficiency and heats the motor if you try to use it as VFD. Starting or positioning only. It is not a substitute for a VFD.

Remember mecganical power is torque times RPM. Electrical is volts times amps times power factor. Actually electrical in motors is flux power which is purely reactive plus torque power which is purely resistive except at stall where you are doing no work. Power factor is nearly zero at zero RPM. So if we cut voltage, flux and torque MUST be reduced by the same amount

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## Signode (Oct 9, 2016)

Hello;


My question is still open. 

Is there any soft starter available which ramps up the voltage to get real SOFT START?


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## gpop (May 14, 2018)

Signode said:


> Hello;
> 
> 
> My question is still open.
> ...


Your definition of a soft start probably can not be done by a soft start.

I have a 125hp fan that is used for both suction and blowing on a sealed system. It takes about 8 seconds to spin up then goes into bypass.
Across the line starting it could be up to speed in less than 2 seconds if the mcc and the tiger tooth belt could handle the stress. 
In this instance the soft start is used to stop the fan from pulling to many amps and to reduce the stress on the belt. 

I have a 125hp centrifuge that can not be started across the line as the load is top heavy for the motor to start. I need to slowly bring the load up to speed over 10 minutes. This can not be done by a soft start so the centrifuge is on a vfd. 

From what you have already posted your fan is starting and drawing around 400% of fla at reduced voltage which quickly drops as the fan gains speed (thats a lot less than a full voltage 700%+ rotor lock start). The belts seem to to be able to handle the torque. So whats wrong with the way the fan is starting. Any start softer than that will require a vfd.


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## Signode (Oct 9, 2016)

What's wrong with that, the life of belts has become almost half because during startup and during transition, belts produce noise due to slippage though they are fully tight. This did not happen during star delta operation. If I increase the transition/bypass time, it is against operation requirement. Blower should reach to full speed within 12sec.
For me, this is happening because of only 2legs operation (one phase is direct). Now I am thinking to install a vfd to get a smooth start.


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## paulengr (Oct 8, 2017)

Signode said:


> Hello;
> 
> 
> My question is still open.
> ...




Yes soft starters torque or voltage control, your choice.


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## paulengr (Oct 8, 2017)

Read this. It’s from ABB but it’s a great background explaining how soft starts work and basic guidance on setting one up for different applications. Pay attention to the torque curves.

https://library.e.abb.com/public/6b4e1a3530814df0c12579bb0030e58b/1SFC132060M0201.pdf



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## gpop (May 14, 2018)

What transition. You dont gave the soft start wired in some type of wye delta do you


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## paulengr (Oct 8, 2017)

Signode said:


> What's wrong with that, the life of belts has become almost half because during startup and during transition, belts produce noise due to slippage though they are fully tight. This did not happen during star delta operation. If I increase the transition/bypass time, it is against operation requirement. Blower should reach to full speed within 12sec.
> For me, this is happening because of only 2legs operation (one phase is direct). Now I am thinking to install a vfd to get a smooth start.



Now we get to the bottom. That’s not a soft start. That’s a belt murderer. You can’t use that junk soft start except on direct drives to pumps and fans and even then, I wouldn’t do it. It’s cheap junk.

If your soft start is one of those super cheap Chinese made crap ones made by ABB, Schneider, and some other European manufacturers that doesn’t have at least 6 SCRs (2 per phase) that’s not a soft start that I would ever use. You get full voltage on one coil of the motor and reduced voltage on two others. Care to guess what that torque pulsing is doing to torque and your belts when you’re alternating between across the line torque and reduced torque?

Belt wear and tear happens partly from friction during running, mostly from internal rubbing, but also stretching during starting as torque goes above name plate. If the belt slips mechanically something is wrong. Your torque drops to 25-30% if a belt ever slips on the first time. Google static vs. sliding vs. rolling friction. In engineering school we used 25% of torque as a good estimate for friction during slipping/sliding. You might do better but not much. The surface basically carmelizes and chars which makes a very slippery glazed surface, ruining the belts grip permanently so at best you get 50% torque. No amount of belt dressing fixes it. Replacement is the only option. Either the belts were loose or the belt drive is undersized or sheaves are undersized. Get the Dodge Power Transmission Handbooks off Baldor/ABBs site and check your belt drive sizing.

Don’t buy that crap drive. That’s like buying a soft start without a bypass contactor...it saves a few bucks in exchange for additional motor heating and noise and reduced life of the soft starter.

Schneider and ABB both make good ones. Those garbage soft starts are made for fly by night contractors that bid a cheap price and vanish before the problems start. There is a reason those soft starts are priced cheaper than the same size starter. Care to guess how much filtering and heat dissipation you paid for? None,


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## Signode (Oct 9, 2016)

gpop said:


> What transition. You dont gave the soft start wired in some type of wye delta do you



I am sorry I mean BYPASS.


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## Signode (Oct 9, 2016)

paulengr said:


> Yes soft starters torque or voltage control, your choice.



So what do you people think, which one should i select, torque control or voltage control?
For me voltage control will be ok so that voltage should start from zero to full in given time.


I had trapped by Schneider who soled me out a cheaper but very bad soft starter. Dont know on which places it is used with one leg direct.


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## gpop (May 14, 2018)

Signode said:


> I am sorry I mean BYPASS.


Never seen that type of soft start used with a bypass. It might be a cheap piece of junk but the ones i have on bucket elevators work fine. They start at reduced voltage and ramp until the full voltage at which point the gate remain closed so theirs no sudden increase in torque. 
The idea that you are soft starting the load then you are suddenly getting a boast of torque near full speed that can make the belts squeal just seems odd. 
Whats even odder is that you said this never happened when you used the wye delta starting.

A sketch or picture of how you have this wired would be interesting as you have converted a wye-delta start to a soft start which means you could have made a mistake.


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## frenchelectrican (Mar 15, 2007)

Now I can see the pieces start coming together .,

OP., you mention wye delta starting system now .

Now the question how they make the connection in the peckerhead ?? it is connected in true delta or run mode connection ? or still half arsed connected in the pecker head and how many tails comming out of the motor ? 6 or 9 or 12 tails ( leads ) ? 

Let us know that details that may give us more clue on that.


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## paulengr (Oct 8, 2017)

Voltage control is best for fans and pumps and any other variable torque or low inertia loads. Current limiting is for the others where you need to set a torque and current maximum. On a belt drive you might use both where it voltage Ramos on a variable torque load until it gets close to full speed then current limits the rest of the way.

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## Signode (Oct 9, 2016)

Hi Friends;
Sorry for my late response as i was busy in other assignments.
Here are the power wiring diagram of said motor both when it was running with star delta starter and now on soft starter. Three wires are going from soft starter to motor where they have connected with six leads of motor to make delta connection in motor.


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## paulengr (Oct 8, 2017)

Signode said:


> Hi Friends;
> Sorry for my late response as i was busy in other assignments.
> Here are the power wiring diagram of said motor both when it was running with star delta starter and now on soft starter. Three wires are going from soft starter to motor where they have connected with six leads of motor to make delta connection in motor.




That’s correct and same way I do it...follow the wiring for the run contactor positions.


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## Signode (Oct 9, 2016)

JRaef said:


> ATS48, but I would over size it by at lease one size up.



Now I am going to install Schneider ATS48 37kw.


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## micromind (Aug 11, 2007)

If the Y - Delta starter worked ok, why change it?


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## Signode (Oct 9, 2016)

micromind said:


> If the Y - Delta starter worked ok, why change it?



Good Question. Actual goal was to increase the number of start/stop per hour i.e. when machine stops for some reason, trim blower should be off. Because it happened that some time machine was off for more than 30min but trim blower remained ON.


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## JRaef (Mar 23, 2009)

Signode said:


> Good Question. Actual goal was to increase the number of start/stop per hour i.e. when machine stops for some reason, trim blower should be off. Because it happened that some time machine was off for more than 30min but trim blower remained ON.


Hmmm... we may have a problem here, depending on the REASON behind that decision.

Using a Soft Starter (or any other Reduced Voltage starting method for that matter) cannot increase the number of starts-per-hour that a motor is capable of. Yes, it can reduce the starting current, but in the process of doing so it increases the starting _time_. So the actual ENERGY (defined as power over time) going into accelerating the load, and therefore the heat it produces in the motor, is not fundamentally changed. This is by the way a _very _common misconception.

Now, MECHANICALLY, reducing the starting torque does reduce the net effects of EXCESS torque on the system components; the bearings, journals, pillow blocks, couplings, motor mounts etc. etc. So that alone is often a good reason to do it. Years ago a company I worked for had a slogan for their soft starts as "Electrical solutions to mechanical problems". Very valid reason for doing this. Compared to a Wye-Delta starter it is also still beneficial, because although a Wye-Delta will appear to reduce the starting current (which may or may not be true), mechanically it just trades one big hit for two smaller ones. 

Just don't do this because the existing controller is tripping out on overload, it will continue to do so.


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## Signode (Oct 9, 2016)

JRaef said:


> Hmmm... we may have a problem here, depending on the REASON behind that decision.
> 
> Just don't do this because the existing controller is tripping out on overload, it will continue to do so.



OK. In conclusion, its mean no any soft starter can fulfill my requirement (increase no-of start/stop per hour). I will have to move to VFD. 

OK???


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## frenchelectrican (Mar 15, 2007)

Signode said:


> OK. In conclusion, its mean no any soft starter can fulfill my requirement (increase no-of start/stop per hour). I will have to move to VFD.
> 
> OK???


To order to use the soft start you will have to read the soft starter specs to see how many starts per hours that unit is rated for ., if you pass the X number of starts per hours either upsize it or go with vsd and may upsize it too. 

that something you have to think about it when you order it.


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## JRaef (Mar 23, 2009)

Signode said:


> OK. In conclusion, its mean no any soft starter can fulfill my requirement (increase no-of start/stop per hour). I will have to move to VFD.
> 
> OK???


A VFD will be able to increase the Starts-Per-Hour, yes, so long as your acceleration profile (the time from stop to start) is not critical (and you don't use DC injection Braking). With a VFD, you can limit the current and torque to 100% of the motor rating and if you never exceed 100% of the motor FLA, you can do that as much and as often as possible. Generally speaking, if a motor can RUN a load, it can START a load. But that starting process at 100% FLA may end up taking a longer time than your machine or process can live with. Only you can determine that.


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## paulengr (Oct 8, 2017)

Stopping in particular is a challenge with VFD's. There are 5 options when it comes to stopping:
1. Just let the motor coast to a stop or at any deceleration rate less than that. This doesn't add extra energy to the motor.
2. DC injection braking. This adds energy to the motor and it's not a particularly effective braking method. So it both adds heat (reduces starts/hour) and doesn't stop all that well. I haven't actually intentionally used this method in years for that reason. It's a cheap way to do it if you don't have a regenerative drive.
3. Regenerative braking. This requires an active front end, not free wheeling diodes. In this case we run the drive "backwards". The front end becomes the inverter and the back end (motor end) becomes the converter. Power is transferred from the motor to the line side. This is so effective that on an AC dragline excavator we were able to run up to around 12 MW forward (accelerating) and up to around 6 MW braking (decelerating). When the machine is stripping material and back filling a previously dug hole it actually generates power from the potential energy stored in the dirt. Deceleration can't happen faster than acceleration except with an overhung load (think stopping an elevator going in the up direction) where gravity assistance helps.
4. Brake choppers. Basically same as #3 except we add resistors and blow a bunch of energy out of the drive through a big heater.
5. Mechanical brakes. Can potentially be the fastest stopping method, just no energy recovery.


And contrary to what is being said, you CAN lock the maximum current through a soft start to 100% of FLA and get the same kind of advantages (infinite starts) but the torque is going to be rotten. It works if you've got a variable torque load like a fan or pump but doesn't work effectively otherwise. VFD's are still a better way to do this. It's just that if we reduce current without reducing the frequency then torque has to go down where instead if we can maintain the same V/F ratio (and current also follows linearly) then torque is almost constant.


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## Signode (Oct 9, 2016)

Hello;


Our requirement is almost 8-10starts per hour. For a new application where the trim blower motor is 22kw and start time is around 7sec, i am going to select ATS48 37kw with external thermal overload. Ok?

Kindly guide me that I should use a bypass contactor or not?


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## JRaef (Mar 23, 2009)

paulengr said:


> ...
> And contrary to what is being said, you CAN lock the maximum current through a soft start to 100% of FLA ...


In my experience it will never accelerate... 



Limiting the motor at start-up to 100% current with a soft starter, which means without changing the frequency, results in the voltage being somewhere around 17%, which reduces the peak torque to about 3% of rated. It will just sit there and hum until the ramp time expires and it goes across-the-line, at which time the current jumps to LRC anyway.


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## JRaef (Mar 23, 2009)

Signode said:


> Hello;
> 
> 
> Our requirement is almost 8-10starts per hour. For a new application where the trim blower motor is 22kw and start time is around 7sec, i am going to select ATS48 37kw with external thermal overload. Ok?
> ...



Whether or not you use a bypass contactor is based on whether you can safely (cleanly) move enough air through the enclosure to cool it down. But even if you can, that soft starter is only rated for 5 starts per hour at rated load. You had better call Schneider and ask them how much you need to de-rate it to be able to get 10 starts-per-hour from it. You will likely have to double the size compared to the motor size. Whatever they tell you, get it in writing in case it burns up and they want to tell you that you misapplied it. They have done that to me (luckily, I did have it in writing).


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## triden (Jun 13, 2012)

Signode said:


> Hello;
> 
> 
> Our requirement is almost 8-10starts per hour. For a new application where the trim blower motor is 22kw and start time is around 7sec, i am going to select ATS48 37kw with external thermal overload. Ok?
> ...


Altistart 48 is their industrial model and what you want. I would recommend a bypass contractor to for full speed operation. With the ATS48, you don't need an external overload as it's still protected by the electronic trip unit in the ATS48 if you wire it according to the diagram.


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## Signode (Oct 9, 2016)

triden said:


> Altistart 48 is their industrial model and what you want. I would recommend a bypass contractor to for full speed operation. With the ATS48, you don't need an external overload as it's still protected by the electronic trip unit in the ATS48 if you wire it according to the diagram.



Thanks a lot. Now finally i will install ATS48 37KW for 22KW motor and will feed back here upon installation and commissioning.


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## JRaef (Mar 23, 2009)

Good luck!


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## Signode (Oct 9, 2016)

Hi;

Can any one tell me (on the base of his experience) the technical difference between Schneider soft starters ATS48 and ATS22? I am in doubt which one should i select for said application (trim waste blower).


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## JRaef (Mar 23, 2009)

Signode said:


> Hi;
> 
> Can any one tell me (on the base of his experience) the technical difference between Schneider soft starters ATS48 and ATS22? I am in doubt which one should i select for said application (trim waste blower).


I explained that for you in post #12. The ATS22 only has SCRs in 2 phases, the ATS has them on all 3. 2 phase soft starters are just a way to make them cheap on the initial purchase but may end up costing more in the long run with failures down the road. So there is no valid reason to use them in my opinion.


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## Signode (Oct 9, 2016)

JRaef said:


> I explained that for you in post #12. The ATS22 only has SCRs in 2 phases, the ATS has them on all 3. 2 phase soft starters are just a way to make them cheap on the initial purchase but may end up costing more in the long run with failures down the road. So there is no valid reason to use them in my opinion.



Hi;
As per user manual of ATS22, it has SCRs in all three phases.


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## telsa (May 22, 2015)

Hard as it is to accept, in the Third World one usually has to OVER DESIGN load systems as the national grid is more iffy and your own load is a much larger fraction of the local grid's demand. Your labor is cheaply priced, but your need for capital inputs (costly machines) -- per industrial worker is pretty stiff.

All attempts at shaving on such expenditures usually go for naught. They are usually a complete bust. 

Right here at ET we get a constant stream of queries from Pakistan and India about gear that does not last// won't run as advertized, etc. 

There's no fooling the laws of physics -- or economics. 

(Imports from Red China are cheap, cheap, cheap for a real reason. It's not charity.)


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## Signode (Oct 9, 2016)

After make this case discussed with Schneider, I have finally selected and ordered ATS22D75Q-37kw model for 22kw and 30kw trim blower motors. As the operation will be controlled by PLC, so the max starts/stop per hour will be programed (limited) up to 10.


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## paulengr (Oct 8, 2017)

JRaef said:


> I explained that for you in post #12. The ATS22 only has SCRs in 2 phases, the ATS has them on all 3. 2 phase soft starters are just a way to make them cheap on the initial purchase but may end up costing more in the long run with failures down the road. So there is no valid reason to use them in my opinion.


Are you sure you're not confusing those with the el cheapo ABB PST line?


Sent from my SM-T350 using Tapatalk


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## Signode (Oct 9, 2016)

Hi All;


I have installed Schneider ATS22D75Q soft starter at 30KW motor and attain my goal.
In old soft starter ATS01 (the piece of junk) where L2 is direct and only L1 and L3 are control, the max starting current is as following;


L1 258A >> 445% of full load current

L2 321A >> *553%* of full load current

L3 258A >> 445% of full load current


After installation of ATS22, the starting current is max 250A of all three phases which provides s smooth start. The built-in overload also helped to eliminate the use of external overload. by using of PLC, max start per hours have been limited at 10.


Thanks to all for their valuable inputs.


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