### Re: code to change the motor amp limit

Posted:

**16 Aug 2017, 06:31**There are a few things where the units "drop out". The unit is "1".

Assignment: You live in an area with 50Hz AC current from the wall. How many cycles in a minute?

Answer: The Hz unit is actually 1/s. Maybe "cylces/s", but according to SI it is really 1/s. the cylce (just like turn) is dimensionless. 60 seconds per minute (min = 60s), N = F * t = 50Hz * 1min = 50 (1/s) * 1 min * 60 s/min = 3000 (cycles). That 3000 is dimensionless.

Another example is resistance of sheets of material. The resistance is expressed as "ohms / square". where the "square" is dimensionless (1m/1m).

Similarly the "turn" and "termination" parameters/factors are dimensionless quantities.

If you like the quantities in your formula better than those in the standard formula: Good for you!

The whole motor-KV-calculation is a bit tricky: if you send an object moving at 10ms you can calculate how long it will take to travel 20m. But for a motor starting with say a CAD model of the motor, the materials used, go ahead and calculate the KV. Very difficult. I'm sure there are expensive motor-design-software-packages that can do it, but there is probably just a numeric simulation involved to solve some equations that we can't analytically solve.

So you have this motor with 100kV and say 100 turns. Now I rewind that motor with aluminium wire because I heard aluminium is also a good conductor of electricity. I use the same thickness and manage to cram in the same 100 turns. So you predict my kV with your formula. The conductivity of aluminium is 61% of that of copper.

Assignment: You live in an area with 50Hz AC current from the wall. How many cycles in a minute?

Answer: The Hz unit is actually 1/s. Maybe "cylces/s", but according to SI it is really 1/s. the cylce (just like turn) is dimensionless. 60 seconds per minute (min = 60s), N = F * t = 50Hz * 1min = 50 (1/s) * 1 min * 60 s/min = 3000 (cycles). That 3000 is dimensionless.

Another example is resistance of sheets of material. The resistance is expressed as "ohms / square". where the "square" is dimensionless (1m/1m).

Similarly the "turn" and "termination" parameters/factors are dimensionless quantities.

If you like the quantities in your formula better than those in the standard formula: Good for you!

The whole motor-KV-calculation is a bit tricky: if you send an object moving at 10ms you can calculate how long it will take to travel 20m. But for a motor starting with say a CAD model of the motor, the materials used, go ahead and calculate the KV. Very difficult. I'm sure there are expensive motor-design-software-packages that can do it, but there is probably just a numeric simulation involved to solve some equations that we can't analytically solve.

So you have this motor with 100kV and say 100 turns. Now I rewind that motor with aluminium wire because I heard aluminium is also a good conductor of electricity. I use the same thickness and manage to cram in the same 100 turns. So you predict my kV with your formula. The conductivity of aluminium is 61% of that of copper.