Yamaha EF1000iS and 3-wire circuit analyzer

[rtcassel]

Originally Posted by wbmiller3

My Yamaha showed hot/neutral reverse. (socket is upside down on the generator). I tried 2 different testers with the same result.

Thanks for checking. I was hoping you would get the same result that I did.

[rtcassel]

I got this tester at Home Depot
http://www.amazon.com/Sperry-Instrum.../dp/B000NB27YI
It is green and is badged by Commercial Electric. Cost $10. Could not find it at HD online. It was the only such tester at the HD that I went to.

It uses 3 colors of lights (red, green, yellow) and so the light patterns are different than the old one, but it has the same 6 conditions listed except the first label Open Ground on the old one is called Bad Ground on the new.

Anyhow, the generator tests out as Bad Ground, which I think is what I want to see. Do you agree, Bill? SEE LATER POST

I may just have to go out and find another one like the old one and see what that says.

[rtcassel]

I found a number for Yamaha Customer Relations. I called, explained the situation, and asked if there was someone I could talk to. I was told that all Yamaha's technicians are in the field, and was given the address and phone number of the nearest dealer and the technician there would talk to me even though I had not bought there.

The dealer was helpful. They only put oil in a generator when it is sold, so they could not use my tester to show what another one showed. The technician said that the Yamaha's are never mis-wired, but could not explain my reading without knowing how the tester is wired. He suggested getting a new tester and comparing. It was a good idea.

[rtcassel]

Originally Posted by rtcassel

I got this tester at Home Depot
http://www.amazon.com/Sperry-Instrum.../dp/B000NB27YI
It is green and is badged by Commercial Electric. Cost $10. Could not find it at HD online. It was the only such tester at the HD that I went to.

It uses 3 colors of lights (red, green, yellow) and so the light patterns are different than the old one, but it has the same 6 conditions listed except the first label Open Ground on the old one is called Bad Ground on the new.

Anyhow, the generator tests out as Bad Ground, which I think is what I want to see. Do you agree, Bill?

I may just have to go out and find another one like the old one and see what that says.

I just tested it again with a new $5 tester like my old one. Same green, green, orange (now yellow, yellow, red).
So I tried the new $10 tester again. A good outlet tests with a bright green. The generator shows not as bright red, and this time I noticed that the yellow is faint and goes out when the generator turns off. This pattern indicates hot / neutral reverse.

[TM Pilot]

rtcassel,

I'm not a professional electrician, so here is my amateur opinion (any professionals please correct me if I'm wrong somewhere). First of all, the TM's electrical system is wired like a sub-panel. The neutral is not bonded to the ground. And there is no earth/dirt ground (you have no ground rod buried in the dirt and connected to the TM frame) - so the entire electrical system on the TM is "floating." But when you plug your TM into the grid, somewhere in that system the neutral is bonded to the ground and the ground has grounding rods buried in the dirt. So if you use your receptacle tester to test the electrical panel you plugged your TM into and the outlets in your TM, they should have the same results (if wired properly) as if you tested the outlets in your home. Now if you plug your TM into an inverter generator and use your receptacle tester to test the outlets on your inverter generator and the outlets on your TM, the results will be different. This is okay. The reason is because inverter generators are "floating" too. Their neutral is not connected to ground and they have no earth/dirt ground (no ground rod buried in the dirt).

I have a Champion 3100 watt inverter generator (Model 75531i). With nothing plugged into the generator, I then plug only my receptacle tester into the 20amp outlet on the generator and I get an open ground reading - middle yellow light illuminated (see picture 1). This is normal because the neutral is not bonded to the ground (floating neutral) by intentional design from Champion's engineers. In addition, the side red and side yellow lights on the receptacle tester dimly flickers. When I test the 20amp outlet with a voltmeter between the hot leg and the ground pin and the neutral leg and the ground pin they both show approximately 57-60 volts (both legs are hot). When I test the 20 amp outlet between the hot and neutral legs it shows approximately 125 volts. If I add a continuous load to the generator (in this test - a miter saw) the 125 voltage drops for 1-2 seconds then stabilizes back to approximately 123 volts. The 57-60 volts on each leg fluctuates and then stabilizes to approximately 95-105 volts during the test. These readings are also normal. From Champion's website (http://www.championpowerequipment.com/faq/):

10) What is "floating neutral" and how does it affect my generator?

Most Champion Power Equipment generators have a "floating neutral", meaning that the neutral circuit is not connected to the frame or to earth ground. This also means that both legs on the receptacle are hot legs, which is normal for floating neutral generators. As a result, there is no specific hot leg and neutral leg wiring arrangement for the generator winding connection to the receptacle. The floating neutral configuration is common for applications such as connection to a recreational vehicle and connection to home power where the transfer switch does not switch out the neutral to ground connection.

The floating neutral eliminates the potential of being shocked by contacting a hot leg and the generator frame at the same time, which could occur if an electrical device such as a hand held tool suffered from an internal short circuit.

Meters or other devices intended to indicate polarity may not properly indicate polarity on a floating neutral circuit. Polarity indicators generally measure the voltage across the neutral and ground connectors. In electrical systems where the neutral is bonded to ground, the voltage will be zero and correct polarity will be indicated. In systems where the neutral is not bonded to ground, voltage is also not expected across this connection. However, in a portable generator some very small current voltage readings can be recorded by sensitive volt meters. This voltage may be induced in the frame by the magnetic field of the generator. The current associated with this induced voltage and the risk of electrical shock are negligible. However, very sensitive polarity meters may interpret this voltage as an indication of reversed connections.

If you have an indication of reversed polarity, please check with the manufacturer of your meter to determine if that reading capability applies to the floating neutral output from a portable generator.

When I plug the TM in to the 30 amp outlet on the generator, all three lights on my receptacle tester now brightly illuminate when it is plugged either into the generator 20amp outlet or the TM (See pictures 2 & 3). When I test the 20amp outlet with a voltmeter between the hot leg and the ground pin it now shows 27 volts and between the neutral leg and the ground pin now shows 19 volts (again, both legs are hot). When I test the 20 amp outlet between the hot and neutral legs it still shows 125 volts. This configuration is also with a 2nd ground connected between the TM frame and the ground terminal on the generator. If I add a continuous load to the generator (in this test - a miter saw) the 125 voltage drops for 1-2 seconds then stabilizes back to approximately 123 volts. The 27 volts and the 19 volts fluctuates then stabilizes back to approximately 25 volts and 18 volts during the test. I believe all these readings are also normal. Remember, an inverter generator's output is controlled by an Electric Control Unit (ECU). It has many differences compared to a traditional generator.

As Champion mentioned, a voltmeter's data has to be interpreted taking into account a floating neutral output from a portable inverter generator. My plug-in receptacle tester obviously doesn't account for this. It's made for electrical systems where the neutral and ground are bonded together (i.e. home electrical panel; RV park electrical panel; bonded traditional generators). Seems your various testers have this limitation too. Therefore, use a voltmeter and interpret it's data considering a floating neutral design. Your generator's wiring is not reversed. It just flows/channels the 120v power differently than the grid does. And the entire separately derived electrical system (TM & Inverter Generator) is "floating." This is okay. For a discussion as to whether or not we should "unfloat" our small inverter generators by grounding them to the earth via a grounding rod and/or bonding the neutral to ground see: http://www.trailmanorowners.com/foru...ead.php?t=7161

Bottom line is that as long as you have 120v between the hot and neutral legs and a ground path(s) from the TM frame back to the generator (your TM plug does this already but you can add a 2nd wire for backup) you and your equipment should be fine. The individual readings between the hot leg and ground pin and neutral leg and the ground pin can fluctuate significantly by the ECU depending on the conditions, load, gen rpm, etc. But it will still output 120 volts. So whether your TM is powered by the bonded & grounded grid or a un-bonded (floating neutral) & ungrounded/floating inverter generator, you're good to go.

[Brittany Dogs]

The 60 volts from hot to ground and then the 60 volts from neutral to ground rings a bell in this way: generators in general rarely have a good earth ground like your house does. The amplitude of the sine wave is based on the difference of neutral and hot giving the 120 volts RMS. The design, if I recall, of these generators need to do that since the whole system is floating. It still works and is safe. Grounding the generator to a good earth ground makes it safer but if I recall, if you put a multi-tester on hot to ground, even if the generator is grounded, it still will show 60 volts. It's been a good 10 years since I did that testing so I'm just going from memory.

12 volt inverters do similar things however due to the stepped sine wave, the RMS value is like 160 volts between hot and neutral and that is because it is sort of fooling the multi-tester since the multi-tester units are designed with the assumption that the sine wave is normal and smooth.

[Brittany Dogs]

I just did meter readings on two Honda 2000i generators. I used my dual-column gas chromatograph, Hewlett Packard model 5710a with flame analyzing detectors. Just kidding, that line was for you "My Cousin Vinny" fans out there.

I used my Sears multi-meter set to AC volts.

I also plugged in one of those three light testers discussed below. Mine has a red neon light then two yellow colored neon lights. As most have discovered, if you test the inverter generator with that tester, you'll get about half the brightness in the neon lamps and it will show the red and the first yellow neons glowing indicating a (false) hot and neutral reverse reading.

Set up: generator with Eco off, a 60 watt load placed on one of the duplex outlets, generator having no ground connection.

Using the AC meter, hot and neutral read 126 volts. Hot and ground read 64 volts. Neutral and ground read 62 volts. Unloading the 60 watt lamp load made no difference in these readings. Grounding the generator to a 6 foot copper ground rod made no difference in these readings.

Using a second Honda 2000i generator, perhaps six years newer than the above generator made no significant difference other than that generator produced 122 VAC between hot and neutral and like above, hot to ground was about 2 volts higher than neutral to ground.

I also noticed that the voltage climbs upward from a cold engine to when things get settled out in a minute or so as the engine and windings warm up. While the voltage and engine RPM are computer controlled, from start up the voltage was closer to 115 VAC then went up slowly to 122 within the first 30 seconds or so. Probably give it another minute and it would probably settle at 125-126 or so.

The bottom line is, while some will contend that the neutral is hot, and as hot as the hot side, the items that are plugged into these generators will still see a "proper" ~120 volt AC, 60 hertz energy source.