voltage control ramping to vibratory feeder tray 4

[ericthered1]

Hello, I am new to your forum, what a wealth of knowlege and experience. My problem lead me here.I know you guys can help....I need to be able to control ramp up speed of a vibratory feeder tray ,say under $300.When I switch it on I want voltage to go from 0.volts to 115volts in three minutes or so.A pot to increase or decrease time would help allso. Ramping down to a stop is not important. FLA3amps/115volts Any help would be appreciated.

 

[itsmoked]

Very easy to do.. IF! It's a three phase motor. Not easy to do if it is a single phase motor. Sounds like it's a single phase motor?

How many horsepower is the motor? Perhaps the motor could be changed to 3 phase for less than $150?

 

[ericthered1]

It's a single phase 60 cycle vibrating feeder tray to move material.

 

[itsmoked]

Hmmm. How many horsepower is the motor?

 

[jraef]

Actually, what is most important is the design of the 1 phase motor. HP will only determine the rating of the controller, although I think itsmoked was trying to get to the same issue since many really small motors are one of the acceptable type.

If the motor is of the Permanent Split Capacitor (PSC), Shaded Pole, or Universal (AC/DC) type, you will be able to do what you want, albeit the method may be different for a Universal. If it is of the Split Phase or Capacitor Start type, you will not. First determine which design you have.

"Venditori de oleum-vipera non vigere excordis populi"

 

[ericthered1]

What I need to control on start up is not a motor at all. but an electrol magnetic vibrating feeder tray 120 volts , 3 amps , 60 cycles . If it comes on all at once , material will move down the feeder tray by way of vibrating to a pulverizing machine and over amp , if not speeded up gradually.Presently we do this manully .We need start up to be more automatic , once at operating speed. High amp situation can shut off feeder (open a set of contacts)and when low amps are reached feeder tray comes back on gradually, 0. volts - 120 volts in 3 minutes maximum time(time being ajustable by a pot). I hope this is more clear and thanks again.

 

[sreid]

Staco offers motorized Variacs.

http://www.stacoenergy.com/

 

[jraef]

Well, you posted in the Electric Motors and Motor Controls forum, so I ASSumed that it had a motor on it! :-/

Many vibrating feeders use a small electric motor with an eccentric weight as the method of generating vibration. If your's doesn't, then you will need to determine how it is creating the vibration. Some do it with a PWM type DC controller, others with an AC solenoid type device. IF you have a little PC board or a "black box" that your 120VAC goes into, it is most likely a PWM style controller. Many of those have a ramping function built-in, are you sure your's doesn't? If it is electronic and it doesn't have a ramp function already, varying the voltage may not work. The electronic controller would likely just shut down.

If you have the solenoid type, you will have the AC wires going directly to what looks like a short plunger assemly, where the plunger vibrates up and down or back and forth. With that type, you may be able to ramp it by simple ramping voltage. In that case a small motorized pot like what sried mentioned would be the simplest method. Another alternative would be an SCR phase-angle voltage controller. Phasetronics makes a low cost unit called the EP-1 that would cost you around $140, but you would need to ask them to modify the ramp time to be 180 seconds instead of 60 seconds. They will do it for you if you ask nicely, it will just take longer to get it.

"Venditori de oleum-vipera non vigere excordis populi"

 

[ericthered1]

jraef , I have seen the motorized vibraters with the weight at one end to cause a offset motion , this isn't that , the best way I can describe the method would be your solenoid type description. It vibrates a horseshoe type magnet on top of a set of metal E shaped plates set on it's side. Any way I will look into the EP-1 from Phasetronics , I will avoid anthing like a motorized variac . Question , "does a PMW controler vary the control for DC motors"? You people have really been helpfull , thanks!!

 

[jraef]

PWM is just a description of a DC output method for eliciting various types of control. It is used in AC drives, DC drives, vibrators as I described earlier, and is actually at the heart of all "switch mode power supplies", like the ones in your PC, TV, cell phone etc. etc.

So the answer is yes, it could be. Not all DC motor controllers are PWM type however.

"Venditori de oleum-vipera non vigere excordis populi"

 

[nbucska]

Eric:
can you tell us the manufacturer's WEB-site and the vibrators part number?


<nbucska@pcperipherals DOT com> subj: eng-tips
read FAQ240-1032

 

[ericthered1]

nbucska , here is the link , only look at the vibratory feeder . The control box will only turn the vibrater on/off and adjust the speed or strength of the vibrations

http://www.eriez.com/resources/brochures/pdf/vibratory/vb30005smallfeeders.pdf

 

[mc5w]

My experience with vibratory bowls for orienting bolts at the input of a thread roller is that an SCR voltage throttle does not last very long for control of vibration amplitude if it is the case that vibration is done using an electromagnet that attracts a steel armature that is attached to the bowl. These electromagnets can be adjusted or maladjusted to large air gaps that increase total current and the electromagnets seem to be robust enough to tolerate excessive current. That is, thermal rating of the electromagnet is a quite a bit more than the nominal current that it is supposed to draw. They also tend to be a nonlinear load because as the armature pulls in during each half cycle the inductance goes up.

This particular type of vibratory bowl has electromagnets that attract a moving plate similar to the coil and moving armature in a motor controller coil. I have also worked with the types of vibratory finishers that use a motor and revolving weight, but these a 2 different animals as far as control is concerned.

Your 2 best best for controlling an electromagnet type vibrator are for a motorized variable autotransformer or to set up a variable frequency drive to produce variable frequency single phase power. For a motorized variable autotransformer you should use both a primary circuit breaker and a secondary circuit breaker set at slightly below the rating of the autotransformer. For a variable frequency drive you need to use an output inductance to absorb most of the carrier ( unwanted ) voltage and current. A variable frequency drive should also have in the output a thermal motor overload relay that is set to protect the electromagnet and the drive against overheating. In no case should any electronic or software overload relay in a variable frequency drive be trusted to work correctly. An autransformer or variable frequency drive with twice the current rating of the electromagnet would be reasonable.

Also, any bolts for the leaf springs that support these things will not work ( go off frequency ) if the bolts are loose by even 1/8th of a turn.

 

[ericthered1]

mc5w, thanks for your input , I believe you understand the dynamics of the vibrating tray I am using but I need to control the take off speed of the vibrating tray . Can you do this with a autotransformer and a singlephase VFD ? If so , how ? Once turned on and speed is increased by turning up the autotransformer . I need it to gradualy increase it's speed so if it's ever turned off then the whole process could be turned on(and off) manualy or automaticaly , without disturbing the setpoint of the voltage to the vibrating feeder tray .web site search: feeder tray (choose #3) ://

http://www.eriez.com

 

[mc5w]

You could set up your motorized variac with a home position limit switch that will not permit starting until the variac has been returned to say the 30 volt position. If you set up the right logic this return to home at power up or when pushing the start button can be automatic.

The motorized variac will be the easiest method since you are only adjusting the amplitude.

Also, in the case of a variable frequency drive do not expect the electromagnet to work below 10 Hertz or 15 Hertz. Even if you set up a voltage boost to compensate for magnet wire resistance at low voltage and frequency you could have problems with the system hitting a resonance as the frequency ramps up. My experience with shakers and vibratory finishers is that the first resonant frequency is below full operating speed say 2/3 of full speed.

The only thing that you really can do is to play around with both methods.

By the way, Lutron makes a heavy duty dimmer models HP-2, HP-4, and HP-6 that can be programmed for inductive loads up to 16 amps at 120 volts for each pole. The HP-2 is the single pole unit, the HP-4 the 2 pole unit and so forth. You can gang together up to 5 3-pole units. This has 24 volts AC self wetted control inputs for stop, full voltage, increase voltage, and decrease voltage. It also has a 120 volt AC analog control input but for your application you would not want that. It also has an adjustable voltage ramp rate when using the 24 VAC inputs. It should be more than robust enough for your application but your application **WILL** void the warranty. Same goes for using it to control paddle fans.

 

[ericthered1]

Well , it looks like there is more way's than one to skin this cat , motorized variac , motorized autotransformer , VFD etc. I don't understand how to use a varible frequency drive for this purpose , but the rest seems clear enough . I think the idea that looks the easiest and cheapest from my eyes is the SCR phase angle voltage controller(EP1 series from Phasetronics). I think I will try this . At least now I have a good idea on where to start .Thanks

 

[jraef]

Actually, a VFD would be serious overkill for this application, I said it would be similar to a VFD, not the same. I have supplied both systems, and the PWM devices tend to be more complicated, but smaller and cooler than the SCR voltage control types so they are favored by OEMs. If you are starting out or doing a one-off application, you are probably making the right choice. Not as much of an investment in time and money.

"Venditori de oleum-vipera non vigere excordis populi"

 

[Steve1000]

Also see REO model IP20

reo-usa.com

 

[jraef]

Wow, have they got that market covered or what? I had no idea there were that many variations.

New info-nugget for the day!

Give Steve1000 a star.