Backup Generator

[AndyC_123]

Hi

Want to get a backup generator for a small office - something like this has caught the eye https://www.parkerbrand.co.uk/8-125-kva-portable-p...

I see it says not for digital equipment... is that them just covering themselves or will we really not be able to power computers with it? If so, are there any generators that can be used?

Many thanks

[Mr Pointy]

Your first task is to total up how much power you need, then you can start looking at suitable generators & working out how you are going to distribute the output safely.

[Evanivitch]

AndyC_123 said:

Hi

Want to get a backup generator for a small office - something like this has caught the eye https://www.parkerbrand.co.uk/8-125-kva-portable-p...

I see it says not for digital equipment... is that them just covering themselves or will we really not be able to power computers with it? If so, are there any generators that can be used?

Many thanks

Why do you need a 7kW output system?

It states not for digital equipment, probably because it has a cheaper modified sine wave inverter. You typically want a pure sine wave inverter for electronic equipment.

[JoshSm]

A good start is using laptops so your client machines aren't affected by power dropouts and can last hours on their own.

Then hang the rest (network kit/servers/etc) off one or more UPS so at least they might stay upright if the power goes and they'll be buffered from glitches on the raw supply. Exclude stuff you can live without like monitors.

Then work out how long you might need the generator to run for, big difference between a cheap one with a rough looking output that doesn't need many hours of runtime, and one you're expecting to hang your delicate systems off for ?? hours.

[ARHarh]

How often do you get power cuts? Sometimes it's just not worth worrying about.

[sjg]

Need a pure sine wave generator for things like computers and LED lighting. Looking at double that cost or so for similar power, considerably more if you want it to be reliable for longer periods.

As said, a small UPS can keep internet/wifi going in a small office for a while so laptops, mobiles etc can keep connected. Beyond that it's what you need - printing? Door access? Phone system, servers? Fridge? Other machinery?

Even so, given 1kw output and 1000Wh is available for £500 or so now with the portable power stations one or two of those would be preferable - many also do power pass-through now so can act as a UPS too.

[RustyNissanPrairie]

AndyC_123 said:

Hi

Want to get a backup generator for a small office - something like this has caught the eye https://www.parkerbrand.co.uk/8-125-kva-portable-p...

I see it says not for digital equipment... is that them just covering themselves or will we really not be able to power computers with it? If so, are there any generators that can be used?

Many thanks

I had a sideline tinkering / selling suitcase generators.
That generator linked is rebranded rubbish. Honda EU series are the default inverter/sine wave output generators. However advancements in powerbanks/UPS capacity have probably rendered them obsolete.

[Gary C]

sjg said:

Need a pure sine wave generator for things like computers and LED lighting..

Why ?

Most switch mode PSU's can take almost anything and the mains ain't exactly a 'pure' sine wave.

Doesn't make much sense to me.

Is it that bad ?

Edited by Gary C on Wednesday 9th July 17:57

[camel_landy]

How much power do you need, how long for and how often?? If you're running servers & switches, they're going to need more planning than simply running a handful of laptops on the end of a broadband link.

If it's to just protect yourself from the occasional 'glitch', what about using a battery based UPS system?

Some pointers...

• Do you all use laptops? If so, they'll all have batteries anyway.
• What's the bare minimum you need? If it's to cover for a short outage, do you need monitors (assuming you're using laptops)?
• External broadband - Run this on a UPS.
• If you go for a generator, are you able to cope with an outage while switching over or do you need it to be uninterruptible (eg DRUPS)?

If you're not careful, it all gets very expensive, very quickly!!

M

[Evanivitch]

camel_landy said:

How much power do you need, how long for and how often?? If you're running servers & switches, they're going to need more planning than simply running a handful of laptops on the end of a broadband link.

If it's to just protect yourself from the occasional 'glitch', what about using a battery based UPS system?

Some pointers...

• Do you all use laptops? If so, they'll all have batteries anyway.
• What's the bare minimum you need? If it's to cover for a short outage, do you need monitors (assuming you're using laptops)?
• External broadband - Run this on a UPS.
• If you go for a generator, are you able to cope with an outage while switching over or do you need it to be uninterruptible (eg DRUPS)?

If you're not careful, it all gets very expensive, very quickly!!

M

At which point just get a 15kWh battery and gateway.

[camel_landy]

Evanivitch said:

At which point just get a 15kWh battery and gateway.

Indeed... A battery wall, with the optional ability to isolate from the mains, so you can operate autonomously during a power cut.

Either way, it'd be useful to have a bit more detail of the requirements.

M

[Griffith4ever]

Gary C said:

sjg said:

Need a pure sine wave generator for things like computers and LED lighting..

Why ?

Most switch mode PSU's can take almost anything and the mains ain't exactly a 'pure' sine wave.

Doesn't make much sense to me.

Is it that bad ?

Edited by Gary C on Wednesday 9th July 17:57

I ran a small rave off a 1.5kva Honda genset (not inverter / pure sine) and everything was happy. Laptops, led lighting (both decorative and stage), laser, 2kw amp, nothing flickered or was unhappy. Didn't try a PC. Wasn't needed. Was rather impressed.

[Condi]

Gary C said:

Is it that bad ?

I think the old ones were "that bad" - older generators, and older electrical equipment. Probably more the older sensitive electrical equipment, rather than the older generators.

OP;

For an office, if you're using any kind of UPS (which you probably should, because it will take you even a short period of time to switch in a generator), then the UPS will clean up what goes out of it. You could run the generator into a UPS and out to the computers etc, that would be fine for any sensitive electrical stuff.

[RustyNissanPrairie]

The issue with non inverter 'gennys is the frequency is determined by the rotating mass (engine) running at a set speed, adding load by turning stuff on momentarily drops the engine speed which drops the frequency. Honda's (again) are fairly stable outputs due to their heavy mass of the rotors, decent carbs and exemplary governor's - none of which will be found in that Chinese clone pictured.

I loved tinkering with the older Honda suitcase generators - the EX650 is a thing of beauty and genuinely whisper quiet.

[Funk]

To the OP - if you decide to go the UPS route you're welcome to give me a shout, I sell this kit (along with IT hardware, software and services); we deal mainly with APC/Schneider, Vertiv, Eaton & Riello. Can also handle any works needed to prep for install etc.

[Gary C]

RustyNissanPrairie said:

The issue with non inverter 'gennys is the frequency is determined by the rotating mass (engine) running at a set speed, adding load by turning stuff on momentarily drops the engine speed which drops the frequency. Honda's (again) are fairly stable outputs due to their heavy mass of the rotors, decent carbs and exemplary governor's - none of which will be found in that Chinese clone pictured.

I loved tinkering with the older Honda suitcase generators - the EX650 is a thing of beauty and genuinely whisper quiet.

Makes sense i suppose, but the first thing a PSU for a computer does is rectify it and whack it across a big smoothing capacitor, then chops it at a variable mark space at 400hz, then put it through more smoothing, the frequency makes little difference.

[Steve_H80]

Lots of good advice for the OP here.
What's hasn't been mentioned so far is the need for a switchover in the office power supply and regular maintenance of the generator. Unless power cuts are a regular thing it's most likely going to be more bother than it's worth.
The OP really needs to take advice from someone with electrical engineering design experience, a cheap building site generator isn't the answer.

[OutInTheShed]

Gary C said:

Makes sense i suppose, but the first thing a PSU for a computer does is rectify it and whack it across a big smoothing capacitor, then chops it at a variable mark space at 400hz, then put it through more smoothing, the frequency makes little difference.

Often not quite true.
There may be a filter or power factor correction on the input, which may not be designed for high levels of harmonics.