3 Phase detection failure needed.

[athenanews]

Please can anybody suggest the best route for doing this. Ideally we would
like a simple flag to let us know if we lose any phases. The flag would need
to be in the form of a 5-12 volt DC signal out to control equipment.

Best regards Steve


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[scada]

"athenanews" <us@gillsteve.giointernet.co.uk> wrote in message
news:40d307bc$1_4@news.athenanews.com...

Please can anybody suggest the best route for doing this. Ideally we would
like a simple flag to let us know if we lose any phases. The flag would
need
to be in the form of a 5-12 volt DC signal out to control equipment.

Best regards Steve


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.669 / Virus Database: 431 - Release Date: 26/04/2004

Two relays rated at the phase to phase voltage. Wire the coil of relay1
across phases A-B. Wire the coil of relay2 across phases B-C. Wire the NO
contacts of each relay in series with both relays, and DC power supply
(5-12V). Now you will loose the 5-12V upon phase loss.

Also the industry uses three phase detectors. I'm not in my office now, but
a google search should show vendors!

If you want to monitor phase current for equality look for a "46 Relay"
(phase imbalance), it allows one to adjust the phase differential trip
point.

 

[scada]

"scada" <scada@optonline.net> wrote in message
news:8MIAc.11463$V57.2253855@news4.srv.hcvlny.cv.net...

"athenanews" <us@gillsteve.giointernet.co.uk> wrote in message
news:40d307bc$1_4@news.athenanews.com...
Please can anybody suggest the best route for doing this. Ideally we
would
like a simple flag to let us know if we lose any phases. The flag would
need
to be in the form of a 5-12 volt DC signal out to control equipment.

Best regards Steve


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.669 / Virus Database: 431 - Release Date: 26/04/2004



Two relays rated at the phase to phase voltage. Wire the coil of relay1
across phases A-B. Wire the coil of relay2 across phases B-C. Wire the NO
contacts of each relay in series with both relays, and DC power supply
(5-12V). Now you will loose the 5-12V upon phase loss.

Also the industry uses three phase detectors. I'm not in my office now,
but
a google search should show vendors!

If you want to monitor phase current for equality look for a "46 Relay"
(phase imbalance), it allows one to adjust the phase differential trip
point.

In addition I should say, if the phase to phase voltage is to large for the
relay coil voltage, then a PT should be utilized. A PT (potential
transformer) is just a step-down transformer. It is a good idea to use in
any case because it offers isolation.