any suggestions for a fast mains changeover system

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I need to make a cct to change over between 2 mains supplies (they are
in phase). The hard part is it needs to change over within around 5 ms
which makes changeover relay out of the question. The current switched
will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
relay but the nature of the lights is they will drop out for about 5
mins with an interuption of about 15ms or greater.

 

[Mike Harding]

I need to make a cct to change over between 2 mains supplies (they are
in phase). The hard part is it needs to change over within around 5 ms
which makes changeover relay out of the question. The current switched
will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
relay but the nature of the lights is they will drop out for about 5
mins with an interuption of about 15ms or greater.

Two solid state relays? These are basically opto isolated
triacs. You'll need a detector/trigger circuit but I don't think
it would be too involved.

Mike Harding

 

[Ken Taylor]

I need to make a cct to change over between 2 mains supplies (they are
in phase). The hard part is it needs to change over within around 5 ms
which makes changeover relay out of the question. The current switched
will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
relay but the nature of the lights is they will drop out for about 5
mins with an interuption of about 15ms or greater.

Is this commercial or are you trying to do a home job on the cheap? There
are commercial change-over units which will do this, but they are definately
not cheap, and don't get in the way of the contactor when it changes -
you'll break your arm!

Cheers.

Ken

 

[Ken Taylor]

I need to make a cct to change over between 2 mains supplies (they are
in phase). The hard part is it needs to change over within around 5 ms
which makes changeover relay out of the question. The current switched
will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
relay but the nature of the lights is they will drop out for about 5
mins with an interuption of about 15ms or greater.

Thought of running them off a UPS so the switch-over doesn't matter?

Ken

 

[amstereo]

If you have 2 powerpoints on different circuits and you tie them together
nothing bad will happen. However, if Your thinking what i think your
thinking - ie, tapping off the hotwater supply and automatically changing
back to regular when hotwater turns off, then you need to use a DPDT
non-latching relay, that, when it discovers load on the switched line, it
holds on to that power source and when it goes off, the relay drops and ur
back on regular. - your refering to MURCURY OR SODIUM LAMPS WHAT ARE YOU
DOING GROWING WEED?

 

[Leon.]

If you have 2 powerpoints on different circuits and you tie them together
nothing bad will happen. However, if Your thinking what i think your
thinking - ie, tapping off the hotwater supply and automatically changing
back to regular when hotwater turns off, then you need to use a DPDT
non-latching relay, that, when it discovers load on the switched line, it
holds on to that power source and when it goes off, the relay drops and ur
back on regular. - your refering to MURCURY OR SODIUM LAMPS WHAT ARE YOU
DOING GROWING WEED?

Well he said it was a problem if they drop out for 5 minutes if the change
over is longer than 15ms.



I guess he just wants to illuminate his tennis court on off peak power.

 

[Rod Speed]

If you have 2 powerpoints on different circuits and you tie them together
nothing bad will happen. However, if Your thinking what i think your
thinking - ie, tapping off the hotwater supply and automatically changing
back to regular when hotwater turns off, then you need to use a DPDT
non-latching relay, that, when it discovers load on the switched line, it
holds on to that power source and when it goes off, the relay drops and ur
back on regular. - your refering to MURCURY OR SODIUM LAMPS
WHAT ARE YOU DOING GROWING WEED?

UNLIKELY THAT THE PLANTS WOULD
CARE ABOUT THE SHORT LACK OF LIGHT.

 

[bruce varley]

I need to make a cct to change over between 2 mains supplies (they are
in phase). The hard part is it needs to change over within around 5 ms
which makes changeover relay out of the question. The current switched
will be about 5A @ 240v (metal hallide lights). Ive tried a changeover
relay but the nature of the lights is they will drop out for about 5
mins with an interuption of about 15ms or greater.

All the UPS changeover switches I've been involved with have used SCRs, and
they could switch so that you could scarcely see the glitch on a storage
CRO.

 

[amstereo]

what about a fat capacitor?I couldn't see why a large mains rated cap
couldn't compensate for a minute loss of power. It'd fill in the blanks (and
may even help with light flicker during normal operation?

 

[Phil Allison]

what about a fat capacitor?I couldn't see why a large mains rated cap
couldn't compensate for a minute loss of power. It'd fill in the blanks (and
may even help with light flicker during normal operation?

** What happens if the AC power is lost at or near a zero crossing ???



........... Phil

 

[amstereo]

Who knows. I'd guess it'd act like caps in pc power supplies, When the power
drops for split-seconds, most pc power supplies can keep the machine running
for the extream short duration that they are out, so i guess, itd do the
same thing.

 

[Phil Allison]

Who knows.

** ROTFLMAO - you sure fucking don't !!!!!

I'd guess it'd act like caps in pc power supplies,

** What ?? - with no voltage and no stored energy ?????

When the power drops for split-seconds, most pc power supplies can keep the machine running
for the extream short duration that they are out, so i guess, itd do the
same thing.

** Still believe in Santa ??

How about the Tooth Fairy ??



........... Phil

 

[amstereo]

nah ran out of teeth to loose.

ever heard of ripple filtering caps? Use a bigger one and it should keep the
light going for the duration of relay switching.

 

[Phil Allison]

nah ran out of teeth to loose.

ever heard of ripple filtering caps? Use a bigger one and it should keep the
light going for the duration of relay switching.

** What happens if the AC power is lost at or near a zero crossing ???


Did I hear someone say deja vu ????




........... Phil

 

[amstereo]

well What happens if the AC power is lost at or near a zero crossing ???

 

[Phil Allison]

well What happens if the AC power is lost at or near a zero crossing ???

** Nothing - your hypothetical cap is simply not charged.




........... Phil

 

[amstereo]

well

 

[Phil Allison]

well

** **** off imbecile.





.......... Phil

 

[The Real Andy]

well

Come on Phil, he is only young.

amstereo, you cap idea my work for DC. Think about how a cap works.

 

[amstereo]

not likely