gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090404-1624 EST
Today on my voltage plot from about 1400 to 1615 EDT there was a fairly consistent square wave modulation of the 120 V line voltage of very close to 1 V. The total period of one cycle was about 2 minutes, and mostly 1 minute high and 1 low. However, over the two hour period there was variation in the high and low periods, and it was not present the entire time. This does not originate from my load. Remote possibility that my neighbor could be the cause, but I am guessing it originated from the grid.
This ended at 1620 EDT and has held within +/- a couple tenths of 124.0 since then. Current time is 1732 EDT.
If it was a voltage regulator would one see this type of oscillation? I would assume that voltage regulators are designed to avoid tap hunting. If it is not a regulator problem are there any types of industrial loads that might produce this type of variation with this period? It was very much a square wave change meaning within 1 to 2 seconds for the transition from high to low. My voltage measurement is quantized in 1 second averages.
.
Today on my voltage plot from about 1400 to 1615 EDT there was a fairly consistent square wave modulation of the 120 V line voltage of very close to 1 V. The total period of one cycle was about 2 minutes, and mostly 1 minute high and 1 low. However, over the two hour period there was variation in the high and low periods, and it was not present the entire time. This does not originate from my load. Remote possibility that my neighbor could be the cause, but I am guessing it originated from the grid.
This ended at 1620 EDT and has held within +/- a couple tenths of 124.0 since then. Current time is 1732 EDT.
If it was a voltage regulator would one see this type of oscillation? I would assume that voltage regulators are designed to avoid tap hunting. If it is not a regulator problem are there any types of industrial loads that might produce this type of variation with this period? It was very much a square wave change meaning within 1 to 2 seconds for the transition from high to low. My voltage measurement is quantized in 1 second averages.
.