Speed Controller For Single Phase Motor

I Brought One Wet Grinder From India To Use At Saudi Arabia. It Fixed With Single Phase Motor 230 Volts /50 Hz, It Is Using For Grind The Rice,all Rice Are Through Out From The Grinder Pot When We Start To Grind The Rice Because Of Motor Runing with Very High Speed(because Line Frequency is 60 Hz). Saudi Arabia Electric Supply 220 Volts 60 Hz. How I Can Reduce The Motor Speed To Same As 50 Hz Speed.suggest In Low Expenses

Thanks In Advance

Can you change the gearing easily ?

Look at BARDAC single phase motor controller. You can control the speed and the frequency easily, and they are CHEAP. $450CAD.

Never seen an inverter which supplies single phase out, altough with Single Phase In -> 3 Phase out are common.

I believe those are driven by pulleys and belt. One option as Simon mentioned will be to change the size of pulleys to reduce speed, but for how long the coils can take it before the temperature rise and trips it is a ?

Change it for a small 3phase (dual voltage - 6wire) motor and then fit a single to three phase (220V) invertor to it.

There is the VARIAC: http://www.variac.com/staco_240_1ph.htm

A variac is a variable AC transformer, many motors can use a variable transformer for speed control.

Motors that usually can be controlled by varying the motor voltage:
Universal Motors
Series Wound Motors
Torque Motors
Shaded Pole Motors


Motors that sometimes cannot be varied by changing the motor voltage:
Split Phase Motors
Permanent Split Capacitor Motors
Repulsion Induction Motors
Motors with centrifugal switches
Motors with fan cooling can sometimes be damaged due to the decreased cooling effect at lower speeds (depending on load).

Did you guys not read my post?

SINGLE PHASE VARIABLE SPEED CONTROLLER!!!

Ok, so noone else should provide any other options? What if he does not have a PSC or shaded pole motor? What if that drive is not available to him?

One of the supplied options may be readily available at about same cost as another, we do not have enough information to state which option is the one to choose.

I don't know what is inside Bardac but as Ron said, you cannot control the speed of a single phase motor other than with a variac / powerstat transformer or perhaps a rheostat.

Three phase motors can be controlled by changing the frequeny or number of pair poles f = N*p/60. Since the number of pair poles is fixed you can only change the frequency which is what all VFD drives do.
You tell me how Bardac controls speed of a single phase motor?

Besides, Variac only offers a very crude form of speed control, you will be losing torque at slower speeds.

SNK..your single phase motor controller costs $450 Canadian dollars...FYI: grinder Mr.Chandrasekhar mentioned here costs Indian Rupees.5000, may be lil more (=120 canadian dollars)..

we have to find alternate suggestion which costs him less than his grinder price.

Let's do a review of the options:

1. If belt driven then change pulleys and belts to obtain required speed.
2. If chain driven change sprockets etc to obtain required speed.
3. If direct coupled may need to change gearbox to obtain required speed.
4. May be able to use a Variac but the larger the HP size of the motor the more expensive it may be. I think the cost for a 230vac 5HP motor may be around $300 US with 1HP less than $100 US. The prices may vary according to location.
5. May be able to use the BARDAC single phase in/out motor controller that SNK provided, verify the details using either this or a variac.

Did I leave any out?

It depends on how the machine works, how important it is to slow down, and availability of parts. If it is direct coupled and you have a good mechanic/fabricator around, then you may be able to remount the motor and add belts/pulleys or chains/sprockets to obtain the slower speed needed.

rsdoran said:

Did I leave any out?

Click to expand...

6. Change the motor to a 3 phase and fit an invertor
7. Instead of a variac fit a transformer 220V in 185 Out (for instance) This is crude but normally cheaper than a variac and you will need to work out the voltage you require or get a tapped transformer ie 220 VAC Input 0-150,160,170,180,190,200VAC Output.
8. Live with what you have

rsdoran said:

Ok, so noone else should provide any other options? What if he does not have a PSC or shaded pole motor? What if that drive is not available to him?

One of the supplied options may be readily available at about same cost as another, we do not have enough information to state which option is the one to choose.

Click to expand...

SNK,
You made a good suggestion, but not necessarily applicable as rsdoran was pointing out. To further this point, the chances that his grinder is using a PSC motor are slim-to-none, and the chances it is a shaded pole motor are none. Both are low starting torque motors and would not typically be found on something such as a grinder.

That said, it may actually be possible, if not practical as bioplc points out. Those VFDs are recommended for use only on PSC and Shaded Pole motors because the speed switch used in Cap-start motors will not work properly with variable speed and may leave the starting capacitor in the circuit too long. This risks damage to the capacitor and/or the inverter transistors. In reality here though, he does not want to have infinitely variable speed, he just wants to lower the frequency to 50Hz instead of 60Hz. If the VFD is set to a very fast acceleration it might get past the problem area quickly enough.

That VFD actually made by Invertek in the UK, so more likely available in Saudi Arabia under that name rather than Bardac who just brand labels it in the US. If interested in that option you could always contact them and explain it to see what they think.
http://www.invertek.co.uk/products.asp?product_id=9&top=products

Still spendy for a low cost machine however. I would think it would be cheaper to find a new 60Hz motor if it is direct drive, and certainly changing a belt sheave is the lowest cost solution.

After considering various suggestions (If changing the pulley & belt is not good enough)I think the cheapest solution will be replacing existing motor, to suit the local specifications.

________

Rewind the motor to the local Area electrical spec