3 Phase, monitor phase rotation? Optocoupler maybe.

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#3024946 20-Jan-2023 20:17

I'm pretty sure that the ABB relay will do what you want, but here's a more configurable Schneider option: https://www.se.com/ww/en/product/RMNF22TB30/nfc-3-phase-monitoring-relay-harmony-8a-2co-multifunction-208480v-ac/

Current sensors may work but would only work once the motors are drawing current - you'd have to turn the contactors on, detect phase rotation (and writing/debugging the software for that is going to be fun), then stop & restart one of the motors once it's already rotating. That's plugging - you need to upsize contactors and potentially consider motor duty limits because it's a lot rougher than straight DOL.

MrJohn

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#3024954 20-Jan-2023 20:34

I changed my thinking regarding the logic of the correction process and decided to start the motors whichever way has been selected at the control panel before starting the logic engine.

Therefore there will be current when the tracking sensor detects mis-alignment. The signals from the current transforms will then be used to determined gantry direction and from that determine which is the leading motor and pause it.

MrJohn

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#3024959 20-Jan-2023 20:51

SomeoneSomewhere:

I'm pretty sure that the ABB relay will do what you want, but here's a more configurable Schneider option: https://www.se.com/ww/en/product/RMNF22TB30/nfc-3-phase-monitoring-relay-harmony-8a-2co-multifunction-208480v-ac/

I can see where that one will alarm on phase sequence but I did not see if it would, or would not, connect when out of sequence.

Current sensors may work but would only work once the motors are drawing current - you'd have to turn the contactors on, detect phase rotation (and writing/debugging the software for that is going to be fun), then stop & restart one of the motors once it's already rotating. That's plugging - you need to upsize contactors and potentially consider motor duty limits because it's a lot rougher than straight DOL.

I am now going to let the motors start before doing phase detection. The motors will run according to the direction set at the remote control which might preclude using smart-Alec contactors, I would like to use soft start/stop solid state contactors if I can find suitable candidates for this job.

Software? I am hopeful that I can manage that.

gregmcc

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#3024961 20-Jan-2023 21:11

Looks like you are trying to electrically solve a mechanical problem.

right away it seems to me that you are wanting to do prescribed electrical work, you do not appear to have enough knowledge or legal qualifications to be doing this, pretty much every electrician knows about the good old under/over voltage/phase failure/phase rotation relay and the variations on this.

My advice, engage someone with the experience and qualifications to do this, all those offering advice on how to do this, should not be offering the advice.

fix the mechanical issue and there wont be an electrical issue to solve.

MrJohn

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#3024971 20-Jan-2023 22:00

gregmcc:

Looks like you are trying to electrically solve a mechanical problem.

right away it seems to me that you are wanting to do prescribed electrical work, you do not appear to have enough knowledge or legal qualifications to be doing this, pretty much every electrician knows about the good old under/over voltage/phase failure/phase rotation relay and the variations on this.

My advice, engage someone with the experience and qualifications to do this, all those offering advice on how to do this, should not be offering the advice.

fix the mechanical issue and there wont be an electrical issue to solve.

Please see EWRB web site and learn if an electrical design is prescribed work.

EMB

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#3024980 21-Jan-2023 00:25

Would it maybe be easier to use a VFD to control one of the motors and increase or reduce its speed as required to correct the misalignment.

SomeoneSomewhere

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#3025001 21-Jan-2023 06:14

I can see where that one will alarm on phase sequence but I did not see if it would, or would not, connect when out of sequence.

I think you're thinking about the purpose of the relay a bit wrong.

There's no real difference between it 'alarming' (or not) and 'connecting ' (or not). It's just outputting two signals and it's up to you what you do with them.

For the ABB one (configured by DIP switch for phase correction), I believe one relay energizes when everything is correct (all phases present, sane voltage and frequency) regardless of phase rotation. The other relay output indicates whether phase sequence is CW or CCW.

The Schneider one is very configurable and you can AND/OR any options you like to drive each of the two internal relay outputs. For example, you could set it up so that one relay energizes when everything is OK and rotating CW, and the other when everything is OK, rotating CCW.

Slight frame challenge: do these motors have electric brakes? It's quite common for equipment like this to have brakes built into the motor that are spring-applied, and released electrically the moment the motor receives power - they're connected directly to the motor supply
I wonder if, when the brakes are released and the motors are *not* powered, the gantry would naturally straighten out under gravity. It might be that all you need to do is supply power immediately to the brakes (to release them), but delay starting the motors for ~2s. You wouldn't need any fancy electronics, just a timer, contactor, and maybe a separate transformer for the brakes as they often use the motor windings to step it down.

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MrJohn

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#3025003 21-Jan-2023 06:36

I think you're thinking about the purpose of the relay a bit wrong.

There's no real difference between it 'alarming' (or not) and 'connecting ' (or not). It's just outputting two signals and it's up to you what you do with them.

For the ABB one (configured by DIP switch for phase correction), I believe one relay energizes when everything is correct (all phases present, sane voltage and frequency) regardless of phase rotation. The other relay output indicates whether phase sequence is CW or CCW.

The Schneider one is very configurable and you can AND/OR any options you like to drive each of the two internal relay outputs. For example, you could set it up so that one relay energizes when everything is OK and rotating CW, and the other when everything is OK, rotating CCW.

Thanks, that does seem to meet my requirement nicely.

Slight frame challenge: do these motors have electric brakes? It's quite common for equipment like this to have brakes built into the motor that are spring-applied, and released electrically the moment the motor receives power - they're connected directly to the motor supply
I wonder if, when the brakes are released and the motors are *not* powered, the gantry would naturally straighten out under gravity. It might be that all you need to do is supply power immediately to the brakes (to release them), but delay starting the motors for ~2s. You wouldn't need any fancy electronics, just a timer, contactor, and maybe a separate transformer for the brakes as they often use the motor windings to step it down.

I do not know about braked or not but they are motor and worm reduction in one unit. The gantry moves horizontally and I do not think gravity would play a part in alignment.

If there are brakes and the brakes are quick acting that may contribute to mis-alignment at the time of stopping. Worth thinking about.

MrJohn

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#3025004 21-Jan-2023 06:38

EMB:

Would it maybe be easier to use a VFD to control one of the motors and increase or reduce its speed as required to correct the misalignment.

A VFD could be used.

gregmcc

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#3025006 21-Jan-2023 06:58

MrJohn:

Please see EWRB web site and learn if an electrical design is prescribed work.

Your OP did not mention design, it said "What do I need to do to monitor 400v lines and couple to Arduino", not a single mention of the word design

Going down the design track is fine, but your are just as liable to make it "Electrically safe" and judging by what you are proposing I would say no......

MrJohn

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#3025008 21-Jan-2023 07:11

gregmcc:

Going down the design track is fine, but your are just as liable to make it "Electrically safe" and judging by what you are proposing I would say no......

I am always pleased to take good advice from wherever the source and I assume you are qualified to offer that. So, if you would please indicate where/why you judge my proposal to be not electrically safe?

Thank you

gregmcc

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#3025012 21-Jan-2023 07:23

MrJohn:

gregmcc:

Going down the design track is fine, but your are just as liable to make it "Electrically safe" and judging by what you are proposing I would say no......

I am always pleased to take good advice from wherever the source and I assume you are qualified to offer that. So, if you would please indicate where/why you judge my proposal to be not electrically safe?

Thank you

How does Electrical Inspector with over 30 years in the industry, with a primary background in industrial design and automation?

MrJohn

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#3025013 21-Jan-2023 07:27

gregmcc:

How does Electrical Inspector with over 30 years in the industry, with a primary background in industrial design and automation?

I am not questioning your qualifications, I am however asking your advice on where do you see my concept as unsafe.

BTW. Please see post #3024542

gregmcc

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#3025017 21-Jan-2023 07:51

MrJohn:

gregmcc:

How does Electrical Inspector with over 30 years in the industry, with a primary background in industrial design and automation?

I am not questioning your qualifications, I am however asking your advice on where do you see my concept as unsafe.

BTW. Please see post #3024542

I'm not going to offer advice on how this should be done simply because this would put me in the firing line should something go wrong.

Looking at the picture it is obvious by the terminology used is incorrect and when the basics like this are incorrect and safe design is unlikely to happen....

MrJohn

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#3025019 21-Jan-2023 08:01

gregmcc:

Looking at the picture it is obvious by the terminology used is incorrect and when the basics like this are incorrect and safe design is unlikely to happen....

Thank you for your advice..

I am going to frame that and hang it on the wall!

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