Phase Loss Detection

[Latte]

Here's one for all the design guys,
Surely there is something out there so when a unit loses a phase it doesn't blow the trips, just cuts the other two phases and then automaticly restores all 3 once they are all up again.

YES i have just been to a site and had to reset nine seperate condensing units following a power cut to a phase

Regards

Raymond

[Mark]

Hi ray

What was the cause? phase loss, single phase out of three for example?voltage drop?phase inbalance?phase voltage surge?.
There are phase failure modules available,but they cant protect against every situation and ££££££.

Regards Mark:)

[Mark]

Ray

A contactor starter c/w manual reset overload ,(Hopefully) cuts power to windings etc before irrepairable damage occurs.
If auto reset were fitted on certain pieces of equiptment then this could lead to more problems:(

Regards Mark:)

[chemi-cool]

hi raymond,

yes, there is such thing!

a phase failure, phase sequence and voltage drop protectio, all in one.

three phses are connected from one side, common, NO and NC contacts on the other side.

if one fase is missing, or, sequence has changed, or, voltage drop below set, relay change position, and alarm goes on. when things go back to normal, it will stop the alarm and restore tention to controls.

hope that helps.

chemi ;)

[Latte]

Situation i had last night was a common problem at this store which is located in the High Street in a fairly large town.

For some reason every 5-6 months the 400amp fuse on a phase blows at the local substation. Most other shops are either completly off or on depending which phase supplies them but obviously this supermarket has all three phases going to it.

What this means is the trip/overloads blow to protect the compressors but an engineer has to wait on site until the electricity board restores power to that phase so everything can be reset.

My point was could this be done some other way !!!


Regards

Raymond

[Brian_UK]

Ray, it could be possible to fit a phase failure monitor that would open a three phase contactor to remove ALL power from the condensers (or whatever plant).

If the condensers are self restarting on power up then it should work.

Obviously some cost involved but shouldn't be horrendous.

[chemi-cool]

hi raymond,

the way you describe it, there is not much you can do untill electricity supply comes back.

what i meant was to protect the refrigeration gear, once any phase gone - it stops, when all three phase back in the right order, machines come back to work.

as simple as that.

chemi :)

[DaBit]

What about having a fat 3-phase relay with 220V coil, and 3 small relays with 220V coil?

Now, the 3-phase relay switches all three phases. The other three relays must be switched in series, feeding the 3-phase relay coil. Power for the three small relay coils should come from each phase.

Now, if one phase fails, the associated relay opens up, cutting power to the 3-phase relay, switching off all three phases.

I don't think you can do it cheaper or easier than this, but you need the neutral connection too (in addition to L1, L2, L3 and earth), which is not always available.

in a simple ASCII graph:


L1 N L2 N L3 N
| | | | | |
UUUUUU UUUUUU UUUUUU

L1 ---- Relay1 ------- Relay2 -------- Relay3 ------>coil 3ph
N ------------------------------------------------->coil 3ph

[chemi-cool]

hi dabit.

thats fine but more complicated from the little device that I offer him.

you can get it at any electric supplier.

chemi :)

[Mark]

Ray i hope this is chargeable work Lol:D

Regards Mark:)

[Latte]

OH YEEH,
It's the contract that has just gone fully comp but i have put chargable in large letters on my jobsheet as i assume this is chargable.

The kind of callout i like (And there isn't many i do). Sit about at a store for a couple of hours, drinking Coffee's waiting for the power to come back on, Can't beat it.
I could have spent the time constructively cleaning cases but then OH Well!!!!

regards

Raymond

[Mark]

The kind of callout i like (And there isn't many i do). Sit about at a store for a couple of hours, drinking Coffee's waiting for the power to come back on, Can't beat it.


Inevitably you took a flask full of coffee with you :D

Lol:D

[Latte]

OH NO
Experience tells us down here that it is always the yellow phase that blows at the substation. The Tea room plugs sockets obviously work off the blue or red because these always work.
All that cuts out at the store are some of the store lights and obviously the compressors.

Regards

Raymond

[Mark]

No wonder you cant sleep Lol :D :D

Too much caffeine:)

Cant see you being a de-caff man;)

[Latte]

Next time you see my van have a look inside, all the ingredients are in there for the engineer on call.
Empty coffee cups & a packet of Pro-Plus on the dash.
Must not forget the B & H in the door pocket as well

Regards

Raymond

[Mark]

Some of us dont need chemical motivation:D :D

[grabber01]

Good job there isn't a HEALTH(y) & Safty Forum Raymond, You Wouldn't stand a chance.

[Latte]

Just because i am not healthy OR safe doesn't mean i don't know the legalaties of it and how it should be done.

Joking aside, it might be a good idea for a forum or is it coverred in any of the other ones.

regards

Raymond

[chemi-cool]

hi raymond,

you might find help here, www.curezone.org.

chemi :)

[frank]

tried the link Chemi but it said I was not authorised to view it - is this some secret smoking forum you belong to? :D

[Latte]

Sorry Chemi,
Same problem as frank, Not authorise to view.
If its a cure fo smokeing, there is no such thing !!!!!

Regards

Raymond

[chemi-cool]

what would I do without you,marc? :D

chemi

[frank]

Thanks for the link Marc :) however the site did NOT offer any advice about deafness! so I'll carry on pulling my Todger :D

[chemi-cool]

try this one frank,

http://www.defeatingdeafness.org/ :)

chemi

[Mark]

Chemi-cool are you sure your not British:D

(sense of humour)

[chemi-cool]

I'm not, my wife is.

chemi :)

[frank]

Sorry Chemi - what did you say - can't hear you ! :D :D

[shooter]

we always use a phase loss detector on mains lline coming in. Also a low voltage and a preferent trip as i do this on seegoing vessels. If one of these devices alarm the complete installation is stopped immediatly.
After restore the PLC starts up sequentaly.

[frank]

you can put a phase fault monitor and protector by marrs or whoever makes one, and a delay on break and make, and if you want you can, you can take the break to the units on/off toggle or system off switch, take it to break the signal leg or control voltage leg that calls for cooling and that should end that, period!

I find this explanation very difficult to understand :confused:

[Brian_UK]

I find this explanation very difficult to understand :confused:If you read his other rash of posts Frank I think you will realise that he probably writes as fast as he speaks :rolleyes: I was going to send some fullstops over the sea but missed the seasons last posting date :D

[master rinktec]

We use a phase loss monitor on incoming voltage to the control panel. There is also a phase loss monitor on each of the compressors. These monitor the incoming lines to the contactors as well as the outgoing lines to the motors. The monitor phase loss, phase inbalance, and low or high voltage. They are also able to be set for manual or auto reset.

I had the fortunate chance to walk into a room at the right time. A breaker lost a leg on a 100 HP motor and was single phasing. The customer was fortunate it was caught in time and caused no permanent damage to the motor.

Since then I feel the added cost is cheap compared to the replacement of a compressor or motor whichever is the case.

[botrous]

A Phase loss detector can be made by using 3 relays , let the main contactor coil current pass by 3 relays in series , than the coil of the first relay will have current from Phase 1 and the second from phase 2 and the 3rd from phase 3 , any phase failure will causes a relay to stop, which brakes the current line of the contactors coil ==> the contactor will return to the normally open position and the compressor motor will be protected , as soon as the failure phase go on again , the contactor will work and the motor compressor will work again .
I advise to put a timer delay relay to protect the compressor from quik ON after an off.

[Peter_1]

In that case is a motor protector much cheaper. According Belgium regulations, a motor protector is even obliged in all 3 phase motor systems.
And if you install a motor protector, you don't have to install a fuse anymore.
So why make it difficult if it can be done easy and reliable.

[Abe]

Peter

Can you please post a picture of a motor phase protector?

Thank You

[Peter_1]

You know what I mean, ity's my bad English again

[chemi-cool]

Hi Abe,
Things are getting mixed up a bit.

What Peter shows, is a motor protector which is set some 5% over the rated currant draw of the motor. In the case of a lost phase, the currant in the two phases left, will increase dramatically causing the motor protector to trip.

The other device is a phase loss, phase sequence and voltage drop protector, all in one, this unit operates a control relay and in case of any phase problem, it will cut the control circuit.

Comprende?

Look here> http://phaselossprotection.com/brochureDSP-1L_en.pdf

Chemi :)

[Peter_1]

We buy the phase loss detectors and sequence controllers at 'Farnell in One' in the UK.
They delievr for free within 24 hours, even to Belgium.

Peter

[botrous]

As i posted before about the 3 Relays method for phase fault protection , this is a wiring diagram that may help to understand that method.http://www.kesserwan.net/PhaseFaultProtection.jpg