Delta Power questions

[sweetssounds]

Hello so iv been searching around CB about how to use delta power. I do theatre lighting as a "master electrician " but i only have a lose understanding of how electricity works in its bare form, like before it gets to the dimmers and such.


Here's my dilemma I have a transformer box that is as i understand delta power ( 60A 240v 3phase) I maybe wrong. But it has the 3 fuses like a larger company switch box. ( i will try and send a picture soon) This box has no out of any kind so i would have to go bare wire straight in. What im trying to do is just output straight undimmed power. I would be using this for a smallish concert setting where i am using 6 meyer M'elodie line array speakers and two 600-hp sub's. All the speakers have autovoltage feature with a 240v setting. How would i wire the box so i could just get useable 240v Edison power out of it. Is this even remotely a good idea? And since im running sound would this kind of power create a bad power buzz?

I know the saying if you have to ask it's probably not a good idea. And i don't plan on doing this with out a more qualified electrician (if it's even feasible) I just wanted some info before i go hunt down a better electrician.

thanks again i hope i don't sound too stupid.

 

[JD]

Floating Delta is just bad news. I know what you are saying in that all your equipment is/can be run on 240, but distro equipment is usually configured as Wye, with some outlets wired as if there was a neutral. There is a lot of room for a very dangerous "Oops!" on this one.

 

[ejsandstrom]

Is it a delta-WYE, like most transformers are? Most of the time the transformer has a delta input. Also delta does not mean wild leg. 3 fuses does not mean delta. You need to STOP and call an actual electrician.

 

[FMEng]

The Delta secondary of the transformer may or may not have a neutral tap. If it was designed for motor loads, it won't have a neutral. While the Meyers would be happy enough, I would expect that the sound crew wants their mixer and processing equipment powered from the same source, but with 120 V. Without a neutral tap, that cannot be done, and using another source is what creates the possibility of hum and buzz issues. If it does have a neutral tap, extreme caution is still advised. Delta configurations only provide 120 V from two of the three legs to ground. The third leg is known as a "wild leg." The wild leg is 208 V to ground! Not fully understanding this phenomenon leads to catastrophic damage to 120 V loads! That is why Delta is obscure and often avoided.

 

[TimMiller]

It may be delta it may be wye. You have to get an electrician to meter it and hook up a distro. You cannot simply "wire in" a bunch of Edison outlets, especially with 240, there are separate types of plugs just for 240 to prevent 120 from accidentally being plugged it. A power distro is a breaker box or load center that is designed for portable use and it has a breaker for each circuit that splits off of it. They are availiable in many different outlet and voltage configurations based on your needs.

 

[porkchop]

First off

240v Edison power out

That is not a good idea. Almost all Edison style connectors are rated for 120V. Also having Edison plugs with 240V to ground is a good way to see people that don't know any better damage 120V equipment. If your cabinets have Edison connectors on them you probably want to run them on 120V, or if they are not able to operate on that voltage you should change out the plug to one that is suitable for 240V

With that cleared up, you probably can use the power source for the application you are asking about. What you need to do though is have someone who knows that they're doing come in, look at it and help you select the proper equipment for power distribution. You need some kind of disconnect with breakers for each circuit that you will be running to the speakers. Power distros come in all shapes and sizes and there's probably a rental house that can help you out with this. You will need to know exactly what kind of power you have at that service though, and that's where a qualified professional electrician is going to come in.

 

[STEVETERRY]

First off

That is not a good idea. Almost all Edison style connectors are rated for 120V. Also having Edison plugs with 240V to ground is a good way to see people that don't know any better damage 120V equipment. If your cabinets have Edison connectors on them you probably want to run them on 120V, or if they are not able to operate on that voltage you should change out the plug to one that is suitable for 240V

With that cleared up, you probably can use the power source for the application you are asking about. What you need to do though is have someone who knows that they're doing come in, look at it and help you select the proper equipment for power distribution. You need some kind of disconnect with breakers for each circuit that you will be running to the speakers. Power distros come in all shapes and sizes and there's probably a rental house that can help you out with this. You will need to know exactly what kind of power you have at that service though, and that's where a qualified professional electrician is going to come in.

With all due respect, these statements are simply not correct. I would say you can't use the power source you describe for the application you have.

A transformer with a 240V delta secondary (meant for three phase motors) simply cannot be used to feed a 208Y/120V dimmer system or sound system. No amount of "power distribution" will fix the problem, it actually requires an additional 240V delta to 208Y/120V transformer. If it is a "high leg" delta secondary, this presents yet another set of complex issues. Either way, this is beyond the scope of a CB thread to solve.

Please call a licensed electrician to evaluate the situation.

ST

 

[porkchop]

With all due respect, these statements are simply not correct. I would say you can't use the power source you describe for the application you have.

A transformer with a 240V delta secondary (meant for three phase motors) simply cannot be used to feed a 208Y/120V dimmer system or sound system. No amount of "power distribution" will fix the problem, it actually requires an additional 240V delta to 208Y/120V transformer. If it is a "high leg" delta secondary, this presents yet another set of complex issues. Either way, this is beyond the scope of a CB thread to solve.

Please call a licensed electrician to evaluate the situation.

ST

When I work with our 240V delta to 208Y/120V transformer I consider it a part of the power distribution system. So I apologize for the confusion there. That's actually the exact piece of equipment I had in mind when I was talking about bringing in a knowledgeable person (I should have probably said licenced as well) to help the OP spec the proper equipment. As you said a discussion of the exact equipment is more than we like to talk about so I didn't want to go into the transformer. I only mentioned the disconnect because I've seen people do crazy things with hardware store parts...