RE: Failover generators

["Paul Gale" <groups@xxxxxxxxxxxxxxxx>]

I had a look at a friends old hydro electric generator this weekend -
He lives in an old mill house and just after the Second World War, they
installed a large turbine rigged up to a search light motor (huge!) - you
should see the electronics - just like a scene from frankenstein! The whole
building rocks when this thing starts turning



Paul.



________________________________

From: ukha_d@xxxxxxx [mailto:ukha_d@xxxxxxx] On Behalf Of
Richard Challis
Sent: 26 June 2006 02:42
To: ukha_d@xxxxxxx
Subject: Re: [ukha_d] Failover generators



To anyone looking at this....

Used to work for a firm that made these panels all the time.

We often used controllers from Deep Sea Electronics. They can also be used
to look after the generator, auto start, oil level lockout etc. with the
right instruments and controls on the generator. (avoid the old controllers
from DSE, they didn't have the best reputation, their new kit is fine now.
We have used it from various military sites to hospitals, sat uplink
stations without any issues.)

Contactors were normal types, BUT their electrical and mech interlocks need
to be spot on. Otherwise you will connect your generator to the mains etc
and it tends to get messy!

You need contactors that are mechanically interlocked. IE two contactor
blocks normally each of four poles. We normally switched a 3 phase load and
neutral, but a single phase supply and neutral would be treated the same.
The two contactors had an interlink that prevented with a lever one
contractor from being pulled in if the other was already pulled in. As a
nuts and bolts additional prevention of this occurring the aux NC contract
on each contactor had a coil voltage from it's twin feeding through it, so
electrically and mechanically we couldn't pull in both at once.

We did this for jobs ranging from 32 amps through to 1600 amps. 1 genset
through to 4. If we were running multiple gensets then we had to sync them
before bringing in the contactors to parallel them up, changeback didn't
matter normally.. If it was a single getset we normally didn't sync back to
the mains before changeover. The contactors changed over pretty fast enough
for most supplies. Everything sensitive on this kind of application would
have a on-line or off-line ups depending on how paranoid the designers
was..

Contactors used for this were the same type of arrangement as used for
star/delta changeover.

Usual disclaimers - hooking this kind of gear up to the mains is dangerous
etc etc etc. I expect that you can't do this at diy level on the domestic
side anymore without regs preventing you from doing it. I work in
industrial
power and control so not affected by part P. We just have lots of other
regs
to contend with instead!

Thanks

Richard

----- Original Message -----
From: "Nigel Giddings" <nigel@xxxxxxx <mailto:nigel%40corbenic.co.uk>
>
To: <ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
>
Sent: Saturday, June 24, 2006 6:45 PM
Subject: RE: [ukha_d] Failover generators

Tim

The changeover is quick., there is no syncronisation.

So quick that a PC without a UPS does not reboot.

The panel is purpose built so perhaps the contactors used are selected for
their speed of changeover

Nigel

_____

From: Tim Hawes [mailto:timsyahoo@xxxxxxx <mailto:timsyahoo%40googlemail.com>
]
Sent: 24 June 2006 12:13
To: ukha_d@xxxxxxx <mailto:ukha_d%40yahoogroups.com>
Subject: Re: [ukha_d] Failover generators

Nigel,

Do you synchronise the two phases before switching back to grid
supply, or do you just let it change over?
Maybe phase synchronisation is not that big an issue with domestic loads?

Thanks,

Tim.

On 6/24/06, Nigel Giddings <HYPERLINK
"mailto:nigel%40corbenic.co.uk"nigel@xxxxxxx>
wrote:
>
> Once Grid supply is restored a timer starts, if the Grid remains OK
for 5
minutes it switches back to grid and shuts down the Genset.

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