PSX-240 loud buzzing

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PSX-240 loud buzzing

Postby mtdoc on Wed Sep 30, 2015 12:55 pm

Recently my PSX-240 has started occasionally making a periodic, very loud buzzing sound that lasts for about 5 seconds and repeats several times at about 1 minute intervals. This is quite loud and different then the very low level constant hum that has always been there. It is so loud that it can be heard throughout the house.

I've removed the cover and re-torqued all the connections. Voltages measure ok. The loud buzzing is there with or without the cover on.

The only load on this is my 240V 1hp septic pump. The loud buzz does not seem to correlate with the septic pump coming on which as far as I can tell is not affected.

Anyone have any idea what is causing this or a solution?
mtdoc
OutBack Virtuoso
 
Posts: 82
Joined: Sun Oct 02, 2011 11:16 am
My RE system: Array 1: Sanyo HIT225 X 8 on Wattsun tracker. Array 2: Evergreen ES-E-225 X 12 on shed roof. Midnite e-panel with Outback GVFX3648, FNDC and Midnite Classic 150 X 2. 436 AH AGMs. PSX-240, Honda eu2000i X 2.

Re: PSX-240 loud buzzing

Postby klundquist on Wed Sep 30, 2015 2:42 pm

Does it appear that the noise could possibly be from the Fan?

Does the noise still happen when the 25A breakers on the PSX are turned off? You might want to switch off the circuit to your septic pump to make sure it doesn't try to start up when the PSX breaker is off.

Did you add another inverter or do you just have one GVFX3648?

-Kurt
Kurt Lundquist
Alpha Energy Systems Engineer
http://www.alpha.com/solar
klundquist
Alpha Energy Engineering
 
Posts: 686
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My RE system: VFX3524, Mate, 200Ah 24V AGM Battery Bank

Re: PSX-240 loud buzzing

Postby mtdoc on Wed Sep 30, 2015 9:39 pm

No, it is not coming from the fan. It is a deeper buzzing sound that seems to come from the transformer itself.

No, with the breakers off it does not happen.

I only have one GVFX3648 which is why i need the psx240 to give me 240V for the septic pump.

Thanks for your thoughts!
mtdoc
OutBack Virtuoso
 
Posts: 82
Joined: Sun Oct 02, 2011 11:16 am
My RE system: Array 1: Sanyo HIT225 X 8 on Wattsun tracker. Array 2: Evergreen ES-E-225 X 12 on shed roof. Midnite e-panel with Outback GVFX3648, FNDC and Midnite Classic 150 X 2. 436 AH AGMs. PSX-240, Honda eu2000i X 2.

Re: PSX-240 loud buzzing

Postby klundquist on Thu Oct 01, 2015 8:53 am

What were your voltage readings from line to line and line and from each line to neutral? What is the neutral to ground voltage? Try to see if the voltages remain static when the transformer starts screaming. I would expect some voltage variation when the buzz is loud. If you have a AC rated CT (current clamp) try clamping L1 and watch the amp flow to see if you can correlate anything to the buzzing sound. Do the same for L2. Transformer hum is caused by expansion/contraction of the coils with varying levels of magnetic activity caused by voltage/current flow.

The loud buzz does not seem to correlate with the septic pump coming on which as far as I can tell is not affected.


Did you turn off the breaker for the circuit that feeds the septic pump? Are you sure nothing else is wired to L2 in your critical loads panel? The float switch for the septic pump could also be an issue. Do you have a well pump as well? It might be a good test to try shutting off the main breaker in the critical load panel. If the buzzing goes away I suggest turning off all the critical load breakers, turning the main breaker back on, then try running just one circuit breaker at a time.

Still having problems? If you have a Mate you can press AC IN and then Drop the grid to try running off of just inverter power. After you drop the grid, shut off the breaker in your main house panel that feeds the GVFX system. The critical load panel should be running off the inverter now. If you lost power when shutting off the AC breaker you need to flip the bypass breakers on the E-Panel. If you still hear buzzing from the transformer shut off the critical loads panel again. At this point you should have the system simplified to the point where it is just the inverter and the transformer without a load. If you are comfortable with wiring you could try swapping the hard L1/L2 wires from the transformer where they tie in at the dual pole 25Amp breaker. Leave the wires on the other side of the breaker that run to your power system where they are. Make sure to turn off your inverter before doing any wiring and use your voltmeter or an AC pen to verify the circuit is dead. I wouldn't expect this to change anything but you never know.

When you re-torqued the connections in the PSX-240 did you also torque the connections inside the E-Panel? Make sure to shut off AC and DC breakers before opening up the E-Panel.

Good luck!

-Kurt
Kurt Lundquist
Alpha Energy Systems Engineer
http://www.alpha.com/solar
klundquist
Alpha Energy Engineering
 
Posts: 686
Joined: Tue May 31, 2011 7:23 am
Location: Arlington, WA
My RE system: VFX3524, Mate, 200Ah 24V AGM Battery Bank

Re: PSX-240 loud buzzing

Postby mtdoc on Thu Oct 01, 2015 11:12 am

Thanks for the trouble shooting suggestions. Some of these I've already tried - some are more difficult due to the very intermittent nature of the buzzing.

To answer some of your questions: No - there are no there other 240 V loads, no well pump. Turning off the critical load subpanel or the breaker to the transformer (on the critical load subpanel) shuts off all input to the transformer - so no it will not buzz in that scenario.

All voltages measure ok on the PSX-240 when there is no loud buzzing but I have yet been able to catch voltage measurements when it is buzzing. That was going to be my next step but will probably mean I attach a logging multimeter to it. I do have a clamp meter to check current and will try to catch it during a buzzing if I can.
mtdoc
OutBack Virtuoso
 
Posts: 82
Joined: Sun Oct 02, 2011 11:16 am
My RE system: Array 1: Sanyo HIT225 X 8 on Wattsun tracker. Array 2: Evergreen ES-E-225 X 12 on shed roof. Midnite e-panel with Outback GVFX3648, FNDC and Midnite Classic 150 X 2. 436 AH AGMs. PSX-240, Honda eu2000i X 2.


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