As per the title, this is a very specific figure. Is there a reason it's 127 instead of 120V or 130V?
Saw this on another site https://www.electronicspoint.com/threads/127-volt-standard-voltage.164594/
Much, maybe all, of Mexico supplies single phase power via 2 phases from three phase power. In the US that is known in the power industry as "network power" and is usually 120/208 volts. Now 208 volts sucks. But to get 240 volts from such a configuration, you'd have to have 138.5 volts on line to neutral, and that is a bit too much for most things that want 120 volts. In Mexico they have chosen a compromise where the L-N voltage is just a little high (127 volts) and the L-L voltage is just a little low (220 volts).
Sounds reasonable. Haven't been able to find any search terms that yield anything better.
The Mexican electrical grid is an unstable grid. It is not well maintained and is subject to highs and low of a frequent nature. 127 volts allows for the electrical distributor (CFE) to have greater flexibility in the power delivery. The 127 standard is slightly higher than the 120 standard for the bulk of the rest of North America but allows for variance of as much as 10% and still be within the confines of what is acceptable. For example: if the grid was set to 120 volts and an increase or decrease occurred of 10% (generally acceptable margin of error for power delivery on a single phase line) the allowance would only be to 132 volts or the low of 108. With 127 volt the variance is slightly more substantial - with an acceptable high of about 138 volt and a low of about 114. Generally the delivery system has a tendency to deliver over-voltage as opposed to under voltage and this 127 standard allows for a greater over voltage delivery with less concern of being outside acceptable parameters. In other words, it takes less work and energy to maintain a 127 volt grid than it does to maintain a 120 volt grid.