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diy solar

Dirty power since trying to deploy Trace inverters (not the inverters’ fault)

If you are using a DMM to measure frequency, it’s not worth your time as it’ll pick up noise as errant frequency s it tries to “lock on” to something . A proper visual of an o scope will tell you what you need to know.

Are you fully decoupled from the grid source?

About grounding?
 
If you are using a DMM to measure frequency, it’s not worth your time as it’ll pick up noise as errant frequency s it tries to “lock on” to something . A proper visual of an o scope will tell you what you need to know.

Are you fully decoupled from the grid source?

About grounding?
If you are using a DMM to measure frequency, it’s not worth your time as it’ll pick up noise as errant frequency s it tries to “lock on” to something . A proper visual of an o scope will tell you what you need to know.

Are you fully decoupled from the grid source?

About grounding?
My power shed has 100amp sub panel. I took out the bonding screw, I have a/c fed to the Growatts from that on a 60amp breaker that is off. I have a separate panel next to it that handles the a/c output from the inverters. This box has its own grounding. I have wires going from there to a manual transfer switch in my house. The panel that is fed the a/c from the inverters is where I am measuring hertz with my multimeter. I am also using the multimeter to measure hertz at the sub panel which has the grid power and is right next to it. My multimeter reads 60hz nice and steady when I’m measuring grid power at the sub panel. I read 60hz almost as steady at the panel for the inverters until I put a load on them; then I get the progressively worse readings that I described in the previous post. If I need an oscilloscope to proceed, I will get one.
 
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I posted the pic of the cam switch I have deinstalled to show the jumpers that I had used. Because I didn’t have issues with dirty power before installing this switch, I am leary.
 
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I had some help. A very experienced gentleman kindly came over with his oscilloscope. [Thank you Craig, (I turned him on to this forum)]. He established that the sine wave put out by the four Growatts is pure without noise. I showed him how the hertz increased under load and he would give it some thought. The good news is that he didn’t see anything wrong with the switch I had installed, said it wasn’t backfeeding and didn’t see how it could cause interference. I plan on running and testing the Growatts one at a time. I am wondering if I have interference on a communications cable. I’d like to get back to where I had been with my Growatts before I move onto the Traces.
 
I showed him how the hertz increased under load and he would give it some thought.
Not sure if you are referring to Growatt or Trace inverters for this comment.

Hybrid inverters may do this when input AC breaker is just opened.

Open AC input is toughest for hybrid inverters to detect since the pass-through relay is engaged with the running inverter is connected to AC input so when grid AC input breaker is opened, the AC input on inverter still has AC voltage fed back through pass-through relay.

It must determine there is no AC input by lack of AC input current draw or out of range frequency wander. Since zero AC input current is a valid input state under certain conditions (like no load on inverter) it may take some time before inverter releases pass-through relay when you switch off the AC input breaker.

During this period, the inverter may wander off frequency since it does not have grid to keep it in phase sync. Either one of two things happen to cause inverter to recognize there is no AC input connected and release pass-through relay, also causing inverter to move to its internal center AC frequency. One is inverter drifts beyond its AC input frequency limit, other is a current detected on AC input that does not fit the inverter/AC output load condition.

Since grid has tight tolerance on its frequency it is better to keep its AC input allowed frequency range tight to get a quicker pass-through relay release.

A true grid interactive inverter that allows grid back feed will purposely attempt to wiggle its phase periodically looking for AC current wiggle that will result if a valid AC input is present which will resist any inverter phase wiggle attempt. If there is no resistance to the phase wiggle, then the inverter declares the AC input invalid (disconnected or high impedance) and releases the pass-through relay.

On my Trace inverters if I double switch the input breaker off, then back on, then back off again within a second or two, it will immediately release pass-through relay. Inverter then slews back to its self-controlled center frequency.

Normally when grid collapses it drags down the AC input causing an overload on inverter which then immediately releases pass-through relay.
 
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Not sure if you are referring to Growatt or Trace inverters for this comment.

Hybrid inverters may do this when input AC breaker is just opened.

Open AC input is toughest for hybrid inverters to detect since the pass-through relay is engaged with the running inverter is connected to AC input so when grid AC input breaker is opened, the AC input on inverter still has AC voltage fed back through pass-through relay.

It must determine there is no AC input by lack of AC input current draw or out of range frequency wander. Since zero AC input current is a valid input state under certain conditions (like no load on inverter) it may take some time before inverter releases pass-through relay when you switch off the AC input breaker.

During this period, the inverter may wander off frequency since it does not have grid to keep it in phase sync. Either one of two things happen to cause inverter to recognize there is no AC input connected and release pass-through relay, also causing inverter to move to its internal center AC frequency. One is inverter drifts beyond its AC input frequency limit, other is a current detected on AC input that does not fit the inverter/AC output load condition.

Since grid has tight tolerance on its frequency it is better to keep its AC input allowed frequency range tight to get a quicker pass-through relay release.

A true grid interactive inverter that allows grid back feed will purposely attempt to wiggle its phase periodically looking for AC current wiggle that will result if a valid AC input is present which will resist any inverter phase wiggle attempt. If there is no resistance to the phase wiggle, then the inverter declares the AC input invalid (disconnected or high impedance) and releases the pass-through relay.

On my Trace inverters if I double switch the input breaker off, then back on, then back off again within a second or two, it will immediately release pass-through relay. Inverter then slews back to its self-controlled center frequency.

Normally when grid collapses it drags down the AC input causing an overload on inverter which then immediately releases pass-through relay.
I was referring to the Growatts. We were measuring htz with my DMM on one leg of the inverters’ output and running a 660w load. At the time I had no a/c input, but the readings were similar to the behavior you describe, jumping around and then settling back down, maybe the inverters searching for something. The sine wave on the scope seemed to hold steady, and Craig commented that if the hertz was changing, the display would move left or right, which it wasn’t. I had also taken to heart the comment made by 740GLE about the draw backs of relying on the meter for hertz. I currently have the Growatts running and l am cautiously running most of what they had been handling before the two incidences where I blew out some led lights in the house. I am keeping my fingers crossed. I am still trying to get a better understanding of what happened. And I still intend to get the Trace inverters running. This forum, you in particular, have been great.
 
I feel obliged to leave a follow up on this thread even though it reflects badly on me. During my up grades, I had installed the knife switch in the attached picture to break the neutral in the grid half of my transfer switch. During previous renovations I had inadvertently crossed two of my circuits neutrals. Even after installing the transfer switch, I hadn’t noticed because electricity was finding its way back to its source. I ran my system this way for a while until I realized that grounding for the TT system at my house needed a three pole transfer switch to switch over to the TN-S system for my off grid system. I added the knife switch to break the neutral at the transfer switch during my up grades to incorporate my Trace inverters. With the knife switch open, I was interrupting the return path on two of my circuits. When fixtures started going funky, all my suspicion fell on the Trace inverters and the rotary switch I was suspecting earlier in this thread. I am a bit embarrassed, but I feel that I have gained more knowledge, and I am proud that I figured it out by watching a lot of videos and with the help I got here. Thank you.
 

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Footnote: The Trace inverters have been running flawlessly since I resolved my problem.
 
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