Susan Brown
Hi Carlos,
The tolerance is 3% of 13 ohms, which is plus or minus about 0.4 ohms (13 x 0.03 = 0.4)
So, 12.6 to 13.4 would be within spec.
Another way that 3% tolerance can work is if the three windings were within less than 3% of each other, the motor would still work even if they were all a little off from 13 ohms. (For this example, if two windings were 12.6 and the third was, say, 12.4)
Some manufacturers give rules of thumb, like being within “half an ohm” of each other, assuming that techs can’t do math. We like to think that they can!