Honda generator problem

[fizzy]

Power still out after the storm. Not back until tomorrow at the earliest.
I collected our old Honda EB3800 from the warehouse and took it home for my brother. Runs fine - had it on for 12 hours yesterday.
Running fine. Fridges and freezer seem ok on it. Also a few lights. 4g router seems ok on it but the computer ups really doesn't like it. We have 2. One wont power up. The other shows the voltage fluctuating between 205 and 220v - changing all the time. Frequency is shown as ZERO!
My brother only has 1 multimeter with a frequency check and it is showing 0.25khz. - that is 250hz which surely can't be right?

Any ideas?

 

[cheb]

My understanding is computers don't like voltage fluctuations, have you a UPS you can use to smooth the generators output?

 

[fizzy]

My understanding is computers don't like voltage fluctuations, have you a UPS you can use to smooth the generators output?

It is the UPS that doesnt like it! computer will run without it - just scared of blowing the psu.

 

[GRW]

Power still out after the storm. Not back until tomorrow at the earliest.
I collected our old Honda EB3800 from the warehouse and took it home for my brother. Runs fine - had it on for 12 hours yesterday.
Running fine. Fridges and freezer seem ok on it. Also a few lights. 4g router seems ok on it but the computer ups really doesn't like it. We have 2. One wont power up. The other shows the voltage fluctuating between 205 and 220v - changing all the time. Frequency is shown as ZERO!
My brother only has 1 multimeter with a frequency check and it is showing 0.25khz. - that is 250hz which surely can't be right?

Any ideas?

UPS emit Harmonic distortion. On top of that they are very fussy over frequency. Gennys like that EB generally don't have the fine control or mass to deal with UPS.
Often the inverter will start to synch with the genny, then as load ramps up (charger, also SMPS) Distortion & interference increases, the genny output fluctuates outside the UPS tolerance - so the UPS rejects the supply.... without the inverter load, the genny stabilises- so the UPS tries again, and you get a cycle.
Bypass the UPS & run the load direct - chances are it'll work

 

[fizzy]

UPS emit Harmonic distortion. On top of that they are very fussy over frequency. Gennys like that EB generally don't have the fine control or mass to deal with UPS.
Often the inverter will start to synch with the genny, then as load ramps up (charger, also SMPS) Distortion & interference increases, the genny output fluctuates outside the UPS tolerance - so the UPS rejects the supply.... without the inverter load, the genny stabilises- so the UPS tries again, and you get a cycle.
Bypass the UPS & run the load direct - chances are it'll work

It does indeed.

 

[GRW]

It does indeed.

Some UPS (posh business ones anyway) often have the facility to have the battery charging facility switched-out. This drops the load on the genny and removes some of the harmonics.
This can be enough to get the UPS to behave on the generator.
You just re-enable charging once its back on utility.
(That said, given the genny isn't designed for those sorts of loads - it's not really worth faffing with).

 

[fizzy]

Some UPS (posh business ones anyway) often have the facility to have the battery charging facility switched-out. This drops the load on the genny and removes some of the harmonics.
This can be enough to get the UPS to behave on the generator.
You just re-enable charging once its back on utility.
(That said, given the genny isn't designed for those sorts of loads - it's not really worth faffing with).

Mine are quite expensive business ones. Not huge but weigh about 40kg each.
Computers don't use a lot. My brothers gaming machine the worst. Uses about 900w flat out. Genny is 3.8kw. Being a Honda I suspect it's real watts not Chinese ones

 

[voipio]

It would be interesting to see what the generator's output waveform is like, as this may have a bearing on the behaviour of the UPS.

Years ago, I remember a laptop having problems with an inverter's output. The inverter ran other loads OK, just not this one laptop.

 

[dobbslc]

UPS emit Harmonic distortion. On top of that they are very fussy over frequency. Gennys like that EB generally don't have the fine control or mass to deal with UPS.
Often the inverter will start to synch with the genny, then as load ramps up (charger, also SMPS) Distortion & interference increases, the genny output fluctuates outside the UPS tolerance - so the UPS rejects the supply.... without the inverter load, the genny stabilises- so the UPS tries again, and you get a cycle.
Bypass the UPS & run the load direct - chances are it'll work

Interesting stuff!
Just a thought but could you plug a small resistive load into the genny like a 1.5kw heater to fool it into behaving?

 

[Gareth J]

Have an old manually controlled PTO generator. You have to keep it at 50Hz and ignore voltage, which can vary widely. Certainly more or less than the grid's accepted max/min.

The conputery stuff is fine with the fluctuations in voltage. But stuff the Hz control and they don't forgive you.

If you have bigger things cutting in/out, that translates into needing a bigger tractor on a lower speed pto setting, just to maintain correct frequency.

In your case, an inverter generator might be more suitable. But I appreciate that right now, getting whatever generator you can get your hands on working is the most achievable.

 

[500e]

Just look at the waveform even if you stabilize the CPS

 

[GRW]

Interesting stuff!
Just a thought but could you plug a small resistive load into the genny like a 1.5kw heater to fool it into behaving?

That can work yes, though not for certain. Give or take... Once the non-linear part of total load goes above 45-50% of the generator rating, or about the same as a percentage of total load - the chances of issues increase exponentially.
That said - its not consistent. Some combinations work when they really shouldn't, & vice versa.
There are a few other weird anomalies too.
Portable, simple design 2-pole alternators on portable gensets aren't really suited to running inverters at all - they were intended to run power tools and resistive loads - so it's a bit of a lottery. It can & does work (often) if the genny is set up well, the inverter isn't too fussy, and the genny alternators is 2.5 to 3x the rating of the non-linear load.
Capacitor voltage regulated alternators can work better than AVR (cos they are slower to react, my guess is that has a damping effect) but on the flip side capacitors can age & fail rapidly on such loads (my guess being the very high frequency switching of the inverter feedback to the alternator is the cause).

 

[Jack_K]

The odd frequency reading is due to noise in the generator output. Some multimeters handle it better than others. Analog is best.

A modern computer really isn't that sensitive to frequency or voltage. I don't know the minimum or maximum frequency or voltage that'll be ok but they are all designed to accept 50-60hz and 110v-240v as well as a tolerance on either side of that.

 

[Turbo]

Get one of the small camping inverter gennys, it will be enough just to run the computer equipment and should play ball with the ups.

 

[GRW]

Get one of the small camping inverter gennys, it will be enough just to run the computer equipment and should play ball with the ups.

I've not attempted that.... and not entirely sure it'd be successful. In theory... OK, but there seems to be an element of contrary black magic where Gens & inverters are concerned.... and suitcase genny inverters... well a lot can be quite fragile. Its a potentially expensive test.

 

[sako243]

Slightly counter intuitive but can you run the PC off an inverter from a car battery and then have the gennie charge the car battery?

 

[GRW]

Slightly counter intuitive but can you run the PC off an inverter from a car battery and then have the gennie charge the car battery?

Yes, no reason why not. Not the most efficient pathway, but it'd work.
Caveat: a lot of cheaper inverters are semi-sinewave, not full sinewave. Some chargers and power suppliers don't like the semi ones and can get hot/fail.

 

[Matrixx]

Most UPS's have a small voltage/frequency window for input power, so it will just reject any fluctuating voltages/frequency.
bigger UPS's will just go into static bypass.