Percent Load Meter

[racear]

I have a Automotive Honing machine equipped with a analog Percent current load meter. I only use from 65% to 75% in my honing, therefore I need to expand that resolution so that I have a meter that has a larger resolution just in the area I am operating in. I am needing some one that has experience in this area. Can I rework the meter I have or build or purchase another. The motor is on 110volt and I guess it is only measuring current that I am loading the machine with the hone stones. I would appreciate any help here.
thanks
racear

 

[waross]

The easiest way is to find a replacement meter with a larger face. If you replace a 2 inch meter with a 5 inch or 6 inch meter you should have lots of resolution/readability.
Or, you could use a current transducer and go to a 4-20 ma signal. Then it is easy to set zero at 60% and a range of 20% Use a suitable meter and the meter will start to move at about 60% load and be at full scale at 80% load.
After you see the price you may reconsider using a larger meter face.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[racear]

Waross
The meter is now 6 inches across. I can see the movement,but the resolution does not let me know when the cylinder is small in a particular spot. You can see it wiggle and you know it, but you cant use the meter to hone out of the tight spot. Can I rework the meter I have and just change the resolution. I don't care what the load is , just so I have a comparative figure to start with.
racear

 

[Compositepro]

Current flow through an a.c. induction motor is a poor indicator of load. You can use an analog watt meter or something more sophisticated like the instruments made by Load Controls, Inc.

http://www.loadcontrols.com/whatisaloadcontrol/whatisaloadcontrol.html

You will find a more detailed explanation there.

 

[jraef]

Just a word of caution: You appear to want more granularity on your load monitoring. Current, while relative to load, is ALSO relative to the voltage supply and is not exactly linear. In other words it is not always an accurate measure of mechanical loading at the motor shaft. There are what are called Load Monitors that monitor the actual motor kW or what is called "Active Current", which is current adjusted for Power Factor. These are much more representative of actual shaft loading. If you want to increase granularity, I would also consider upgrading your sensing system.

Link to example (without metering output)
Link to example (with metering output)




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[racear]

Even with the meter I have now, I can tell when the cylinder bore is small at one spot, but since the resolution is so small, it is only an indicator. What I was after is a wider range of reading, so that I don't have to stop so often and measure. Maybe I am asking for too much, but I just thought it would be neat, but I cant spend hundreds to do this. It isn't practical or cost efficient. I just want to amplify that one particular part of the load.
thanks you guys
racear