Portable generator questions, really confused

[KeepItSimpleStupid]

1. Transfer connection - Like one of these?**broken link removed**

2. Before you get really involved, just re-route the connections DIRECT to the furnace only from the L14-30 and verify that the N and ground continuity exists at the generator. I would suspect the furnace will work. You can wire nut the connections and it would be nice if you could include a fuse/breaker rated for the furnace. You also have the disconnect at the furnace.
e.g. Get a fuse and lamp socket, wire it in series and wirenut to the incoming power with the switch off. Verify the voltages L-N and L-G and N-G at the furnace and ten throw the switch at the furnace. Bet it will work.

We don;t get may generator questions here.

3. Ideally, you have to break the ground/neutral bond at the generator. This might be tough to do. Run the independent ground back to the ground rod if possible and the neutral back to the neutral.

4. Hopefully, your neutrals and grounds are separate in the transfer panel.

The independent test, should rule out generator compatibility.

What I would say is, that some people make a L14-30 plug and just connect the ground and neutral together in the plug once they have disconnected the ground-neutral bond in the generator. Most people don't need 240 V portable power, so it's a good solution. So, when you need to use the 120 V as portable power, just insert the plug.

 

[driver444]

KEEPITSIMPLESTUPID. I'll bet #4 of your post is my problem. After thinking more about this, am I right to say that there should be only 1 bond between neutral and ground? If the neutral and ground are bonded in the generator, (which they are) they shouldn't be bonded in the panel also, right? My neutral and ground are NOT bonded in the transfer switch...BUT, in the main breaker panel, as per instructions, the neutral and ground wires from the transfer switch ARE connected to the same ground bar, therefore... BONDED. Could that be the issue? Could I then just pull that ground wire off the bar in the panel to break that bond, to see if that works?

OR... Could I just remove the "neutral/ground jumper" in the panel on the generator, to "unbond" them, then ground the generator frame with a rod?

 

[KeepItSimpleStupid]

OR... Could I just remove the "neutral/ground jumper" in the panel on the generator, to "unbond" them, then ground the generator frame with a rod?

That is ALMOST EXACTLY what you have to do, but do not ground the generator frame with a outside rod. Actually, I think, that is optional, but should be done for lightning strike protection.

By doing so, you have to put the bond back when you use the generator stand-alone, like to operate a power tool when not connected to the house.

JUST REMEMBER ONE THING:

The neutral and Ground of the house has to connect at ONE PLACE only.

With the neutral-ground bond broke in the generator, you are effectively paralleling two grounds which is OK. It also means that a direct lightning strike to the generator outside goes to the ground and not thru the house transfer cable.

Get it?

 

[driver444]

That is ALMOST EXACTLY what you have to do, but do not ground the generator frame with a outside rod. Actually, I think, that is optional, but should be done for lightning strike protection.

By doing so, you have to put the bond back when you use the generator stand-alone, like to operate a power tool when not connected to the house.

JUST REMEMBER ONE THING:

The neutral and Ground of the house has to connect at ONE PLACE only.

With the neutral-ground bond broke in the generator, you are effectively paralleling two grounds which is OK. It also means that a direct lightning strike to the generator outside goes to the ground and not thru the house transfer cable.

Get it?

Got it!
Now, to be clear, this should clear up any problems with motors (specifically) running at less than full speed, ie. furnace blower, and bathroom fans, or is the 50HZ that the generator is putting out instead of 60HZ still going to be an issue?
And lastly, is there any reason why I can't wire a switch in the generator panel into that jumper wire so I can more easily switch it from bonded to Not bonded when the need arises?

 

[tcmtech]

I am going to disagree a bit with the seperating the generator frame grounding from the generators electrical neutral point. I am assuming that given that you need a 120/240 VAC 60 cycle power source you have a standard american electrical service setup.

Given that at the main power panel in the house it would most likely have all of the electrical common lines and grounding lines tied together it won't matter if they are tied together at the generator either. From the electrical standpoint the generator putting out 120/240 power would be no different than what the utility source transformer puts out of which it and the meter box all will have shared connections from their respective earth ground and common line sets.

Being that the main house panel already shares a physical connection between its earth ground and common lines any secondary connection or lack there of between them at any power input ahead of that is irelavant.

I am guessing that the OP's spark plug wire tachometer is not the least bit accurate and the whole problem is simply a low frequency issue. Grounding or lack there of with the actual generator has nothing to do with it being that there is not a problem when using utility power.

 

[driver444]

I am going to disagree a bit with the seperating the generator frame grounding from the generators electrical neutral point. I am assuming that given that you need a 120/240 VAC 60 cycle power source you have a standard american electrical service setup.

Given that at the main power panel in the house it would most likely have all of the electrical common lines and grounding lines tied together it won't matter if they are tied together at the generator either. From the electrical standpoint the generator putting out 120/240 power would be no different than what the utility source transformer puts out of which it and the meter box all will have shared connections from their respective earth ground and common line sets.

Being that the main house panel already shares a physical connection between its earth ground and common lines any secondary connection or lack there of between them at any power input ahead of that is irelavant.

I am guessing that the OP's spark plug wire tachometer is not the least bit accurate and the whole problem is simply a low frequency issue. Grounding or lack there of with the actual generator has nothing to do with it being that there is not a problem when using utility power.

This makes a lot of sense too. Basically, what you're saying is, you can't ground something twice. If it's grounded in one place, the presence of another connection somewhere else between the same 2 wires or set of wires is just a redundancy, and functionally makes no difference.

Yes, in my main panel, the neutrals and grounds are all on the same bars. So if it's connected at the generator too, it shouldn't matter because they're essentially already connected.

For the record, my brother-in-law (a licensed electrician) stopped over today, while I was out, (with the generator in the back of my truck, no less), and looked at how I had the transfer switch hooked up. He said it was just how he would've done it. That felt good.

I'm really starting to think the generator is the problem.

 

[tcmtech]

Exactly. If you are getting ~50 Hz readings on the lines with a fair quality digital multimeter the odd are thats the correct reading.

I have used those spark plug wire type tachometers and I don't find them to be all that accurate or reliable.

Given your engine is likely mechanically governed when you set it you should shoot for a 62 - 63 Hz reading at no load. At the full 5500 watt load you should see around 57 - 58 Hz. That's where I aim for when I set up portable generators at.

 

[driver444]

Exactly. If you are getting ~50 Hz readings on the lines with a fair quality digital multimeter the odd are thats the correct reading.

I have used those spark plug wire type tachometers and I don't find them to be all that accurate or reliable.

Given your engine is likely mechanically governed when you set it you should shoot for a 62 - 63 Hz reading at no load. At the full 5500 watt load you should see around 57 - 58 Hz. That's where I aim for when I set up portable generators at.

Yes, mechanically governed. Just a single screw, really easy. Yeah, I'm not even close to that (HZ). Literally, with just one lighting circuit turned on, I was only reading 49-50 HZ at a bulb socket. That's it. When I used that meter on line power I was 59-61HZ. perfect. So the meter is right. I even tried turning the governor up slowly in small increments with the meter on it to see if it would come up. NO DICE. 50HZ...that's it. Wondering if one of the previous replies was correct, (alternator mislabeled/misassembled at factory).

So being 10HZ off (low) could definitely be the cause of inductive loads like motors not getting up to speed? I should get a hold of another generator and see if that changes anything.

 

[KeepItSimpleStupid]

This as come up on another board numerous times and including, my furnace won't work. I was considered an HVAC and Electrical expert among others on the board with 10's of thousands of posts.

So, as I said earlier: Eliminate the generator and use just the furnace and just the generator. The wires all come together in the transfer box. It will look like a "kill me quick". The term someone gave my hook a 200 A (secondary) welder to #8 wire to do a very short weld of A 1/4" diameter stainless tube with a thin wall.

Ground is used as a reference and protective ground. It is particularly used as a reference for the flame sensor. If you have a potential difference between the neutral and the ground, you have a ground loop. Frequency is NOT INVOLVED at this point.

If the line freq is used as a reference then the speed might be 5/6 off, but I doubt your seeing that.

My comments are primarily based on this from the OP:

2. Although all of the things I mentioned that I checked for voltage, all were 121 volts, EXCEPT, when I checked the voltage on the circuits running on "generator" in the panel, I touched one probe on the ground bar, and one on the screw on the breaker itself, (only on the generator powered circuits) and got 153 volts! Why would that be?

Why might that be? An AC out of phase with the generator ground loop?

What is so hard about just connect the generator to the furnace with protection (preferred) in the panel? I'll bet you could put a 120 V plug on the romex from the generator and connect an extension cord to the generator. Your done. The circuit is protected 15 to 20 A , I would expect, and you eliminate everything else/

You answer the question, will the generator run my furnace?

What you have should run a 1/2 HP motor. e.g. 746 W/hp * 5 That 5 is a huge number) or your generator VA divided by 746 W.
If the answer were 1, it would not work. You have something like 6875 VA/746. The furnace surge is not an issue.

I said earlier that the Flame sensor, (if it is flame rectification), depends on the ground and depends on the phase of the 24 VAC transformer.

 

[driver444]

KEEP ITSIMPLE... I'm definitely gonna try it your way before I do anything else. Haven't had time in the last couple days. I did, however, find the bond "jumper" wire in the GEN panel that connects the ground of one of the receptacles, to the neutral on another, and removed it. (and yes, I labeled the generator "FLOATING NEUTRAL". Again, would it be acceptable to install a switch into that wire to "REBOND" easily when I need to use the Gen as a "stand alone"?

Have not tried to wire directly to furnace yet, due to time constraints, (wife and 2 kids).

 

[KeepItSimpleStupid]

A 30 A or more switch may be hard to come by, but it would be OK. Make sure the switch is rated for AC.

Here is a switch: https://www.grainger.com/Grainger/LEVITON-Disconnect-Switch-5HYT6?Pid=search

Now, do you see where you could be better off just using the 240 4-wire plug (With a wire from neutral to ground) because generally you don;t need 240 in standalone mode.

 

[tcmtech]

Yes, mechanically governed. Just a single screw, really easy. Yeah, I'm not even close to that (HZ). Literally, with just one lighting circuit turned on, I was only reading 49-50 HZ at a bulb socket. That's it. When I used that meter on line power I was 59-61HZ. perfect. So the meter is right. I even tried turning the governor up slowly in small increments with the meter on it to see if it would come up. NO DICE. 50HZ...that's it.

So obviously the problem is due to the engine speed being too low so I don't follow the point of messing with the wiring systems because of it.

To get your governor into the right range might take a bit more than a slight turn of the screw like maybe several turns to be honest. Also don't worry about over shooting the RPMs range for a bit while adjusting things. I have seen countless gensets turned way up due to dummies trying to get more power out of an undersized unit. The one place I worked at it was common to see used units come in for tune up that were cranked up to 75 - 80+ hz!

The other option if your screw won't go far enough is that it may be necessary to have to move the spring up a hole or to going away from the pivot point in order to get it to the higher RPM/frequency range.

Either that or you simply just need to bend part of the adjustment linkage to get it there. I and my brother have a number of assorted sizes of Honda and Chonda engines on generators and other things so I am rather familiar with the having to tweak the governor assy and linkages in order to get them to run fast enough.

If I remember correctly either his 3500 or 5500 watt generator had a similar low speed problem, I think the both have the Chonda engines as well, which is why he got it for free and all that needed was a bit of linkage bending to get it up to the right speed.

If I am over at his place any time soon I will try and have a look to make sure I am remembering the right machines and if I am right I will have a look at the governor linkages so I can see exactly what does what on them. I know they are adjustable but I don't know exactly how far using the screws Vs just moving the spring or bending the adjustment linkage.

 

[driver444]

I want to thank everybody for the valuable information, and knowledge.

The award goes to KEEPITSIMPLESTUPID... It turns out that eliminating the second neutral/ground point in the generator did the trick. Everything is running up to speed. So, the lesson of the day is when hooking a portable generator to a transfer switch with not switching neutral, the neutral bond in the generator has to go bye-bye.

Thanks again KISS
Won't ever second guess you again

 

[KeepItSimpleStupid]

driver444

You need to be congratulated too. Your problem description was concise and to the point. We didn't have to pull teeth to extract information.

Generally, you don't put an Electrician in the same room as an HVAC technician except for "HVAC guy, here's the power you asked for".

It so happens, that the generator and the furnace not co-operating, I've seen the problem before with the exact resolution of breaking the extra NEUTRAL-GROUND bond at the generator.

==

Aside:
I remember where a 30 year HVAC tech diagnosed the problem as being a bad water to air heat pump in the ceiling. It got replaced with the help of lots of other people and it would not work.

He asked for my help and I had him do a few things and make a few measurements after studying the diagram. I probably spent 10 minutes with him. I said replace the thermostat wire, there is a short. He did. It worked.

During a recent renovation, the thermostat wire got scraped badly by an metal stud.

So, he did spend an arm and a leg for a part that wasn't needed. I guess I saved his butt.

 

[rumpfy]

I followed this thread with some interest.
In Australia, we have a 230 volt Multiple Earthed Neutral mains power system.
Each mains supply transformer is 3 phase with star connected windings of 230 volt. The star point is the neutral, and is connected to ground at the transformer.
The wiring into each electricity consumers premises has one, two, or three, phase conductors PLUS the neutral. The house wiring has all the neutral conductors returned to a brass 'Neutral busbar' which connects to the mains supply neutral, AND there is also an EARTH connection made from the neutral busbar to a ground stake. A consumer with a 2 phase supply has a phase to phase voltage of 415 volt.
The problem with this system is that if a consumer loses the neutral connection between the switchboard neutral busbar and the incoming mains supply neutral, then the neutral currents will flow to ground to the neighbours switchboard and into their neutral busbar and back to the supply neutral.
In the US system, it seems that each consumer has a 240 volt centre tapped supply. If the mains supply system is 3 phase, then there is 3 separate neutrals for the electricity distribution system. As I understand it, the neutral is floating in the US system.
So, is it possible in the US for consumer to have a 3 phase supply based on the basic 120/240 volt distribution network.
Is it the case that industry uses a 480 volt 3 phase system. If so, how is this arranged.

 

[KeepItSimpleStupid]

In the US Neutral and Ground are bonded at one single point in the distribution. This would typically be the main panel. This type of panel is called a "main breaker" panel. Sub-panels are usually "main lug". They will have an isolated neutrals. A "man breaker" panel can usually be converted to a main lug panel by removing the neutral-ground bond and adding a ground bar. Then the breaker acts as a disconnect. The disconnect breaker could be rated for 200 A and the panel could be fed from a 60 A feed.

You can read the NEC or National Electric Code online for free. It may take me a while to find the URL.

The household consumer typically has a 240 center-tapped feed. It is still true, that loosing a neutral can and will possibly feed from a neighbors neutral by ground current in copper pipes, if used.

The household consumer generally is fed one phase of a 3-phase distribution network and 3-phase for a household consumer is generally not available.
In a few areas of the US it is.

This https://en.wikipedia.org/wiki/Three-phase_electric_power probably doesn;t do a really good job of explaining stuff.

For industrial we have 208Y/120 and typically 240 high leg delta systems.

Industrial may also get 277/480V for lighting and motor loads out of the system as well/

Here is an interesting discussion https://www.control.com/thread/1026182313

I worked in a place with 120/240 and 240 3-phase, but I didn't know much about the distribution there and then we moved to a Y 120/208 and 277/480 panels. The heating/cooling system used the 480 3-phase (32 heat water to air pumps) and 277 was used for lighting.

The move required us to change the heaters in pumps called diffusion pumps for 208 rather than 240.

Any loads we put in were typically 3 phase 208 up to 200 A. A few pieces of equipments used 50 A 3 phase 208, 70 A 3-phase 208 and 200 A 3-Phase 208.

 

[rumpfy]

thanks kiss.
So, for a house, the supply is 240 volt centre tapped 120-0-120 volt, with the centre tap at ground at the consumers main panel. The supply transformer is 3 phase with each phase delta connected. This means there are 3 neutrals from each supply transformer.
But, for industry, the supply is provided as 120 volt star connected with the star point connected as the neutral to give 120 volt single phase and 208 volt 3 phase.
I guess the mains transformer could be the same design for either application but it would need 6 separate windings each with its own centre tap with 18 terminals for strapping.
Is this how its done?

 

[KeepItSimpleStupid]

So, for a house, the supply is 240 volt centre tapped 120-0-120 volt, with the centre tap at ground at the consumers main panel.

True. In my development, there is a single wire on a pole, single phase line that probably supplies 7200 V. 4 houses typically run off of each transformer. Newer developments will opt for underground utilities. My development is > 50 years old.

The supply transformer is 3 phase with each phase delta connected. This means there are 3 neutrals from each supply transformer.

There is only a a single phase high voltage distribution supplying the houses.

There is a school about 500' from me that has 3 phase power because 3 phase power runs along a main road. A sub-station is about a mile (5280 feet) away.

But, for industry, the supply is provided as 120 volt star connected with the star point connected as the neutral to give 120 volt single phase and 208 volt 3 phase.

Industry can be supplied with nearly anything depending on their power requirements. An automobile plant is located about 1.5 miles away and it gets power from the large primary distribution system with huge metal towers which typically run along rail routes.

Where I used to work, we were suppled with something like 9600 V 3 phase. A huge transformer was placed outside and then, I think a lower voltage was run inside underground.

The general system was 480/277/208/120, but I think there was lab we rented out had to supply 240/120 for a Nabertherm furnace, so they got that distribution. When they moved to our lab, it may have been too costly to convert the furnace or it wasn't available in 208.

I guess the mains transformer could be the same design for either application but it would need 6 separate windings each with its own centre tap with 18 terminals for strapping.

Is this how its done?

For a small business like a restaurant, you might see 3 transformers on a pole.

Power distribution can take on many forms. Here, https://longwoodgardens.org/news/press/2011/06/16/longwood-gardens-commissions-10-acre-solar-field is a place that now has a 1.5 MW solar array and is planning to increase to 3 MW. I got a behind the scenes tour of the controls for a HUGE greenhouse and the distribution is all high voltage in the killovolt range. This year's tour was a trip to a micro-brewery. One tour, I missed, was a behind the scenes tour of a suspension bridge. These are local perks of my membership in https://www.isa.org/

See here: https://en.wikipedia.org/wiki/Electric_power_distribution

and See: https://en.wikipedia.org/wiki/Distribution_transformer

 

[rumpfy]

Tks kiss,
In OZ, The HV distribution started historically as a 6.6 kV system with 3 phase supply. Over time, the HV increased to 11 kV and now it is typically 22kV. In any street, a 3 phase transformer will step down to 230 volt. You will see 4 wires on the poles (1 neutral, 3 phase conductors) plus a street lighting wire. generally, consumers take only a single phase supply which is up to 60 Amp. If a consumer has voltage regulation problems, anothe 3 phase transformer is added somewhere nearby.
Large industry will have their own supply transformer(s) and the metering will be done at the 22kV level. The supply will still be 230/415 however. So all consumers have access to the standard 230 volt supply.
The point of all this gets back to the problem of the auxiliary generator and in that case it appears that there was significant current flowing in the neutral wire which upset the generator. This could not happen in Oz because of the MEN system, but in the US it maybe can happen depending on the neutral earthing scheme adopted at each premises.