Estimate electrical frequency from clock shift
About 6 months ago I installed a solar power system with 2 Tesla Powerwalls for backup. Today, we got to test out the system with a power outage from an ice store in the southeast (still on battery power as I write this)
My kids came downstairs to tell me that I was time for bed (9PM), but when I looked at my phone, it was only 8:17PM. They were reading the time off the microwave. I checked the alarm clock in my room and it also read 9PM
I know that the way power is "pushed" around between solar, utility, and the Powerwall is by modifying the frequency of the ac signal. I also know that many digital clocks keep time via utility frequency.
So, my question is this - if our power went out at roughly 10AM, and by 9PM our digital clocks were off by almost 45 minutes, what frequency is the powerwall delivering backup power at? That large of a shift in time seems excessive (purely speculative).
frequency clock
asked 2 hours ago
Matt Matt
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About 6 months ago I installed a solar power system with 2 Tesla Powerwalls for backup. Today, we got to test out the system with a power outage from an ice store in the southeast (still on battery power as I write this)
My kids came downstairs to tell me that I was time for bed (9PM), but when I looked at my phone, it was only 8:17PM. They were reading the time off the microwave. I checked the alarm clock in my room and it also read 9PM
I know that the way power is "pushed" around between solar, utility, and the Powerwall is by modifying the frequency of the ac signal. I also know that many digital clocks keep time via utility frequency.
So, my question is this - if our power went out at roughly 10AM, and by 9PM our digital clocks were off by almost 45 minutes, what frequency is the powerwall delivering backup power at? That large of a shift in time seems excessive (purely speculative).
frequency clock
asked 2 hours ago
Matt Matt
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago
add a comment |
About 6 months ago I installed a solar power system with 2 Tesla Powerwalls for backup. Today, we got to test out the system with a power outage from an ice store in the southeast (still on battery power as I write this)
My kids came downstairs to tell me that I was time for bed (9PM), but when I looked at my phone, it was only 8:17PM. They were reading the time off the microwave. I checked the alarm clock in my room and it also read 9PM
I know that the way power is "pushed" around between solar, utility, and the Powerwall is by modifying the frequency of the ac signal. I also know that many digital clocks keep time via utility frequency.
So, my question is this - if our power went out at roughly 10AM, and by 9PM our digital clocks were off by almost 45 minutes, what frequency is the powerwall delivering backup power at? That large of a shift in time seems excessive (purely speculative).
frequency clock
asked 2 hours ago
Matt Matt
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
About 6 months ago I installed a solar power system with 2 Tesla Powerwalls for backup. Today, we got to test out the system with a power outage from an ice store in the southeast (still on battery power as I write this)
My kids came downstairs to tell me that I was time for bed (9PM), but when I looked at my phone, it was only 8:17PM. They were reading the time off the microwave. I checked the alarm clock in my room and it also read 9PM
I know that the way power is "pushed" around between solar, utility, and the Powerwall is by modifying the frequency of the ac signal. I also know that many digital clocks keep time via utility frequency.
So, my question is this - if our power went out at roughly 10AM, and by 9PM our digital clocks were off by almost 45 minutes, what frequency is the powerwall delivering backup power at? That large of a shift in time seems excessive (purely speculative).
frequency clock
frequency clock
asked 2 hours ago
Matt Matt
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Matt Matt
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Matt Matt
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 hours ago
Matt Matt
111
asked 2 hours ago
Matt Matt
111
111
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Matt is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago
add a comment |
If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago
If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago
add a comment |
2 Answers
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45 minutes over a span of 660 minutes is an error of 6.8%. That's rather high. I would have expected a crystal-controlled frequency with an error of 100 ppm or less — i.e., less than 4 seconds over 11 hours.
And power isn't "pushed" by modifying the frequency per se, but rather the relative phase of the various sources.
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
add a comment |
Units such as APC and Trip-Lite UPS detect 60+/-3 Hz as a power good and either reduce AC load outside this frequency or switch off AC charge to rely on battery backup. They also use voltage thresholds.
However these UPS units have a relatively short backup time compared to the PowerWall2 (PW2) . There are UPS's with +/-6Hz tolerance for input power detection such as the Minuteman.
Therefore to reduce non-essential loads that have short-term backup such as UPS, the PW2 runs > 65 HZ intentionally. or > 7.7% fast.
Your clocks were reading (21:00-10:00) * 60min/h = 660 minutes when you were expecting (20:17-10:00) * 60min/h = 617 min or 43 minutes fast = 43/617*100% = 7.0% fast which was the actual increase on the PW2 or 64.2 Hz.
The PW2 was 10% within the 65 Hz that I expected, but I do not have their actual specifications.
I am aware of this but cannot prove it.
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
add a comment |
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2 Answers
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45 minutes over a span of 660 minutes is an error of 6.8%. That's rather high. I would have expected a crystal-controlled frequency with an error of 100 ppm or less — i.e., less than 4 seconds over 11 hours.
And power isn't "pushed" by modifying the frequency per se, but rather the relative phase of the various sources.
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
add a comment |
45 minutes over a span of 660 minutes is an error of 6.8%. That's rather high. I would have expected a crystal-controlled frequency with an error of 100 ppm or less — i.e., less than 4 seconds over 11 hours.
And power isn't "pushed" by modifying the frequency per se, but rather the relative phase of the various sources.
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
add a comment |
45 minutes over a span of 660 minutes is an error of 6.8%. That's rather high. I would have expected a crystal-controlled frequency with an error of 100 ppm or less — i.e., less than 4 seconds over 11 hours.
And power isn't "pushed" by modifying the frequency per se, but rather the relative phase of the various sources.
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
45 minutes over a span of 660 minutes is an error of 6.8%. That's rather high. I would have expected a crystal-controlled frequency with an error of 100 ppm or less — i.e., less than 4 seconds over 11 hours.
And power isn't "pushed" by modifying the frequency per se, but rather the relative phase of the various sources.
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
answered 2 hours ago
Dave Tweed♦Dave Tweed
118k9145256
118k9145256
add a comment |
add a comment |
Units such as APC and Trip-Lite UPS detect 60+/-3 Hz as a power good and either reduce AC load outside this frequency or switch off AC charge to rely on battery backup. They also use voltage thresholds.
However these UPS units have a relatively short backup time compared to the PowerWall2 (PW2) . There are UPS's with +/-6Hz tolerance for input power detection such as the Minuteman.
Therefore to reduce non-essential loads that have short-term backup such as UPS, the PW2 runs > 65 HZ intentionally. or > 7.7% fast.
Your clocks were reading (21:00-10:00) * 60min/h = 660 minutes when you were expecting (20:17-10:00) * 60min/h = 617 min or 43 minutes fast = 43/617*100% = 7.0% fast which was the actual increase on the PW2 or 64.2 Hz.
The PW2 was 10% within the 65 Hz that I expected, but I do not have their actual specifications.
I am aware of this but cannot prove it.
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
add a comment |
Units such as APC and Trip-Lite UPS detect 60+/-3 Hz as a power good and either reduce AC load outside this frequency or switch off AC charge to rely on battery backup. They also use voltage thresholds.
However these UPS units have a relatively short backup time compared to the PowerWall2 (PW2) . There are UPS's with +/-6Hz tolerance for input power detection such as the Minuteman.
Therefore to reduce non-essential loads that have short-term backup such as UPS, the PW2 runs > 65 HZ intentionally. or > 7.7% fast.
Your clocks were reading (21:00-10:00) * 60min/h = 660 minutes when you were expecting (20:17-10:00) * 60min/h = 617 min or 43 minutes fast = 43/617*100% = 7.0% fast which was the actual increase on the PW2 or 64.2 Hz.
The PW2 was 10% within the 65 Hz that I expected, but I do not have their actual specifications.
I am aware of this but cannot prove it.
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
add a comment |
Units such as APC and Trip-Lite UPS detect 60+/-3 Hz as a power good and either reduce AC load outside this frequency or switch off AC charge to rely on battery backup. They also use voltage thresholds.
However these UPS units have a relatively short backup time compared to the PowerWall2 (PW2) . There are UPS's with +/-6Hz tolerance for input power detection such as the Minuteman.
Therefore to reduce non-essential loads that have short-term backup such as UPS, the PW2 runs > 65 HZ intentionally. or > 7.7% fast.
Your clocks were reading (21:00-10:00) * 60min/h = 660 minutes when you were expecting (20:17-10:00) * 60min/h = 617 min or 43 minutes fast = 43/617*100% = 7.0% fast which was the actual increase on the PW2 or 64.2 Hz.
The PW2 was 10% within the 65 Hz that I expected, but I do not have their actual specifications.
I am aware of this but cannot prove it.
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
Units such as APC and Trip-Lite UPS detect 60+/-3 Hz as a power good and either reduce AC load outside this frequency or switch off AC charge to rely on battery backup. They also use voltage thresholds.
However these UPS units have a relatively short backup time compared to the PowerWall2 (PW2) . There are UPS's with +/-6Hz tolerance for input power detection such as the Minuteman.
Therefore to reduce non-essential loads that have short-term backup such as UPS, the PW2 runs > 65 HZ intentionally. or > 7.7% fast.
Your clocks were reading (21:00-10:00) * 60min/h = 660 minutes when you were expecting (20:17-10:00) * 60min/h = 617 min or 43 minutes fast = 43/617*100% = 7.0% fast which was the actual increase on the PW2 or 64.2 Hz.
The PW2 was 10% within the 65 Hz that I expected, but I do not have their actual specifications.
I am aware of this but cannot prove it.
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
answered 2 hours ago
Sunnyskyguy EE75Sunnyskyguy EE75
63.4k22194
63.4k22194
add a comment |
add a comment |
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If the powerwall has line voltage outputs they should be set to line frequency. What does the powerwall specification/nameplate say? Are you 100% certain that the clocks didn't simply reset during the momentary dropout before the UPS/PTS kicked in?
– K H
2 hours ago
It maybe skipped pulses from switching between power sources. They all may have accurate 60 HZ +/- 0.1 % timing, but it can take several milliseconds to switch power sources. Most manufactures guarantee to switch in 10 mS or less, but even that is a 1 count error. That and built in errors on some equipment can easily add up to 45 minutes in 11 hours.
– Sparky256
2 hours ago