Portable Generator

ducati996 · Jan 1, 2005

Bob,

I think you should look into getting a unit simliar to the one described above. You will save yourself a ton of money, and
you can protect the devices you need to. Thats all you need beside's a generator. You can place surge protectors on your appliances (if 110v), otherwise you will be fine just protecting your electronics with something like the link above.

Ducati

AndyMA · Jan 1, 2005

( I guess you can call that safe and cheap. However, I think a couple hundred dollars is a lot safer and cheaper in the long run. Will your insurance company cover you if something were to happen to your house under these circumstances.
Richard )

I don't know if the insurance company would cover the monetary losses, but that is the least of your problems. The Negligent Homicide charge for those killed by the backfeed would be the bigger problem. As an electrical engineer who majored in power generation and distribution all I have to say is that hooking up a generator with any chance of backfeeding the main line is just plain stupid. And BTW pulling a meter is also a crime. Install a transfer switch correctly. A transfer switch does not have to pull the neutral and must maintain ground continuity.

Andy

SLOBuds · Jan 1, 2005

Quite a few. Try a Google search and you might find something you'd like.

Here's one:

http://www.smarthome.com/4860.html

_RaT_ · Jan 1, 2005

Here's one I have installed for folks.

Intermatic

Soundguy · Jan 2, 2005

( They do have a few millisecond drop out )

I can't speak for other brands.. but APC has this in the 1 ms range.

( It just doesn't condition the line power beyond the surge protectors.
)

Again.. I can't speak about others, but I was a dealer for APC for a while.. their units offer quite a bit of line conditioning, including emi and rfi filtering, in addition to the 3 mode surge protection, they also perform a site wireing check in the form of polarity check and ground check. That is just the bk line.. the smartups do even more and can track power conditions if you use software like power doctor, etc.

Soundguy

Soundguy · Jan 2, 2005

( by the backfeed would be )

I take it someone had a generator hooke dinto the house and hadn't thrown the main breaker?

Soundguy

v8dave · Jan 3, 2005

Ok, I stand corrected. The UPS units Ducati pointed to do have line filtering. The web site Ducati provided will get you to this PDF white paper which describes what various UPS units do. Unfortunately, it is written for other engineers. The real point is in the tables summarising APCs product line at the end of the paper.

It does point out that the APC "Back-UPS" type of UPS is a switched system. A good system, but not as good as APC's "Smart-UPS" product line which does do a power conversion and new waveform generation.

Ducati996, thanks for the link.

The point I was trying to make, but failed, is that a lot of folks think that a UPS will take a dirty generator output and regenerate a clean waveform for running their sensitive equipment. Some will regenerate a clean waveform, some just filter what they are given, they all provide some protection. Just be aware of the differences.

If I were looking for protection from a bad generator I'd go for the waveform regeneration "Smart-UPS" product line. If I were just worried about line hits and cleaning up my power from light dimmers (etc.) the "Back-UPS" product line would do. If I were running speed controllers (electronic/SCR/thrysistor motor control) on multiple HP motors, or frequently starting multiple HP motors while on a standby-generator, I'd protect my sensitive equipment with the big guns double conversion or delta conversion products [multiple product lines here, look at the charts].

If I lived on a mountain/ridge top like Bob_Skurka, I'd do what he did and have a mains protection and also add a wall wart protection on my electronics. I'd also add a secondary filter on my phone lines (in addition to the phone company protection), computer network, and antenna lines. I'd consider one of the higher end APC systems for my entertainment system and computers. But, most importantly, check the protection units after each lightning storm. These surge protection devices do have a load capacity, but mother nature knows no limits. Sometimes, you have to replace the surge protector's guts. Sometimes you have to replace the UPS too, it may have given its all to protect your downstream equipment.

_RaT_ · Jan 3, 2005

Thanks for the heads up Dave, your going over my head. Frankly, when the power goes out here which happens a couple of times to as many as 4 times a year for various times from minutes to a few hours, I feel fortunate enough just to run the well pump, refrigerator and lights if needed, after that it's just icing on the cake for me.

Soundguy · Jan 3, 2005

( The point I was trying to make, but failed, is that a lot of folks think that a UPS will take a dirty generator output and regenerate a clean waveform for running their sensitive equipment )

True.. some people don't make the connection between real time waveform generation, and a transfered standby system.

One thing I'm wondering is where we are getting all of these dirty generators.... I've looked at the waveform on my pto gen, and it 'looks' just like the one out of my home utility plug. Same with a couple smaller gas jobs. On the other hand.. some of the waveforms from various inverters I have produce very questionable sinu-sidal waveforms.. yet so far.. I havn't seen much complain about them except very old ferro-ressonant power supplies. Modern switching power supplies, such as triac'ed models generally have no problem with poor line conditions. Using a variac at school, we fed a 250w computer power supply, and didn't get a shutdown untill we dropped under 90v. Frequency could be adjusted almost 20% +/- as well.. and this was older technology.

I realize that anything that needs a scan reference from the line will have problems with bad frequency regulation.

Looking at the output of my triplite inverter, a no name inverter, and my apc unit.. the apc had the best looking waveform.

Another thing to keep in mind about power supplies, is just about anything that is xformer iso'ed, or is making dc power is also going to be very tolerant of power conditions onthe line, aside from emi/rfi. The inductive effect of the transformer primary and secondary can even make halfway decent sine waves out of square waves. And once it hits a rectifier and some capacitive filtering... only the emi/rfi is an issue.

The point i'm getting at is that many modern gensets are providing cleaner power than most low end invertors.

Higher end invertors, and computer ups systems, including the big matrix systems would obviously be on the + side with the extra filtering and serious active regulation.

Soundguy

BobRip · Oct 27, 2005

I have a bracket which keeps my main breaker from being on at the same time as the generator breaker. Attached is a picture. I found after I made my own that you can purchase them. This is cheap and safe.

Bob Rip