MEP-803A Voltage Fluctuation

[e_beauregard]

Is it normal to see some fluctuation in voltage while warming these machines up? The last few times I’ve started and ran it I’ve noticed the voltage holding 120v, then spiking to 130+ for a few seconds, then dropping back down to 120v. I mentioned during warmup because it always seems to settle out after temps are up. I’ll share a video of what it’s doing if someone would let me know how to share a video here. Thanks in advance


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[2Pbfeet]

Is it normal to see some fluctuation in voltage while warming these machines up? The last few times I’ve started and ran it I’ve noticed the voltage holding 120v, then spiking to 130+ for a few seconds, then dropping back down to 120v. I mentioned during warmup because it always seems to settle out after temps are up. I’ll share a video of what it’s doing if someone would let me know how to share a video here. Thanks in advance


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How often do you use this unit?
What voltage regulator do you have, and have my of the fuse/MOV modifications been done?
Is this warming up under a load?
How dry is your storage area? (AC or no AC? Rain exposure? Condensation exposure?)
How clean are your switches? (When was the last time you ran some contact cleaner / DeOxIt through the switches? (E.g. S1)?)

All the best,

2Pbfeet

 

[e_beauregard]

How often do you use this unit?
What voltage regulator do you have, and have my of the fuse/MOV modifications been done?
Is this warming up under a load?
How dry is your storage area? (AC or no AC? Rain exposure? Condensation exposure?)
How clean are your switches? (When was the last time you ran some contact cleaner / DeOxIt through the switches? (E.g. S1)?)

All the best,

2Pbfeet

I exercise it for about 15-20 minutes once or twice monthly. I haven’t used it for its intended purpose yet, my whole home back-up. I have run it for a few hours with 2 5kw heaters as a make-shift load bank. I don’t warm it up under a load, I wait a few minutes for temps to come up before throwing the heaters on. My storage area is an enclosed metal building without climate control. We have lots of humidity in south LA but it’s never been rained on since I’ve owned it. I cleaned the S6 & phase selector switches with deoxit a few weeks ago. Have not cleaned R1. I’m not sure which voltage regulator I have, but I’m pretty sure the fuse mod was done. I’ll add a pic of what I have!

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[kloppk]

You have the Fuse Mod which is good. You have the original factory AC Voltage Regulator.

 

[2Pbfeet]

You have the Fuse Mod which is good. You have the original factory AC Voltage Regulator.

Plus the MOV mod as well, which is also good.

@e_beauregard @kloppk is much more of an expert than I am, but I associate unstable voltages with two things; a) poor connections/failing insulation, or b) failing components.

I asked about humidity and water, because damp can exacerbate electrical defects in insulation and variable resistance at contacts/paths to ground, and the effects of oxidation and corrosion, especially at moving contacts like switches. Likewise, if the voltage regulator is getting unstable information on voltage, it will behave incorrectly. (Garbage in /garbage out)

So,

assuming that all of the connections are clean and tight, have you double checked the voltage fluctuations with a DVM of known accuracy, and have you checked the voltage at the convenience outlet, voltage regulator sense terminals, and the main lugs, and do those values match what you see on the panel meter?

All the best,

2Pbfeet

 

[e_beauregard]

Plus the MOV mod as well, which is also good.

@e_beauregard @kloppk is much more of an expert than I am, but I associate unstable voltages with two things; a) poor connections/failing insulation, or b) failing components.

I asked about humidity and water, because damp can exacerbate electrical defects in insulation and variable resistance at contacts/paths to ground, and the effects of oxidation and corrosion, especially at moving contacts like switches. Likewise, if the voltage regulator is getting unstable information on voltage, it will behave incorrectly. (Garbage in /garbage out)

So,

assuming that all of the connections are clean and tight, have you double checked the voltage fluctuations with a DVM of known accuracy, and have you checked the voltage at the convenience outlet, voltage regulator sense terminals, and the main lugs, and do those values match what you see on the panel meter?

All the best,

2Pbfeet

Just cranked it up and checked voltage at convenience receptacle (I keep a kill a watt on there), main lugs & sensing terminals on voltage regulator. Just after startup everything was fluctuating the same as the panel indicated. I did notice L1-N was more stable at 120v than L3-N, which was fluctuating rapidly from 117v-138v. Grabbed my other meter & double checked and everything was stable (unit had been running for 8-10min at this point). Checked again with first meter & panel gauges & everything held.


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