[amblin]

Just met a friend who runs a factory making industrial/military power transformers and stabilizers , he agreed to custom made a toroidal transformer for my equipments,  a 1:1， 10 KVA / 10 KW normal load rated transformer box with shielding, dedicated air beakers ,surge /short circuit protection, and sockets included , He can also throw in a separate filter unit for low consumption units.

I'm wondering is this basically the same as those 'power conditiners' on the market? Or is there a catch and could potentially damage my system?

It's mainly for my pair of 14Bst2.

Thanks

Ps. They're a established brand so I think it's not going to explode or burn down the house...

A

[jea48]

Just met a friend who runs a factory making industrial/military power transformers and stabilizers , he agreed to custom made a toroidal transformer for my equipments,  a 1:1， 10 KVA / 10 KW normal load rated transformer box with shielding, dedicated air beakers ,surge /short circuit protection, and sockets included , He can also throw in a separate filter unit for low consumption units.

I'm wondering is this basically the same as those 'power conditiners' on the market? Or is there a catch and could potentially damage my system?

It's mainly for my pair of 14Bst2.

Thanks

Ps. They're a established brand so I think it's not going to explode or burn down the house...

A

 10KVA, 1:1?

If you live in the US or Canada I would recommend the primary winding be 240V and the secondary 120V.

A 10KVA transformer is max rated for 83.33 FLA amps at 120V.   

[amblin]

10KVA, 1:1?

If you live in the US or Canada I would recommend the primary winding be 240V and the secondary 120V.

A 10KVA transformer is max rated for 83.33 FLA amps at 120V.

Hi jea48

A 220v - 220v unit， my local voltage is 220-230v.  Maybe it's better to use two separate 5KVA units for each amp?

A

[Folsom]

What's the advantage to having him build it? Just price?

I'd be weary of filters for the other components. To be very frank, most people don't have a clue what they're doing with those and selling them left and right. And I'm talking about people with experience, degrees, etc etc... There's some smarts in just offering a mostly basic transformer unit (as Bryston does).

Make sure to save enough in your budget to buy a nice hand-truck.

[Speedskater]

There are advantages to having your entire audio system on a single large isolation transformer. With a 240V input and 120V output. With the transformer near but not in the music room. Wire as a Separately Derived System.
Typical North American line voltages have been slowly creeping upward. Now 125V is common, so the transformer needs to be designed for well more than 125V.

Instructions in this Middle Atlantic paper. See pages 19 thru 21.

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper"
http://www.middleatlantic.com/resources/white-papers.aspx

[amblin]

What's the advantage to having him build it? Just price?

I'd be weary of filters for the other components. To be very frank, most people don't have a clue what they're doing with those and selling them left and right. And I'm talking about people with experience, degrees, etc etc... There's some smarts in just offering a mostly basic transformer unit (as Bryston does).

Make sure to save enough in your budget to buy a nice hand-truck.

Actually it's free.. So really difficult to turn down

Met the people during a business trip and saw the huge amount of transformers being made in the production line. They passed CE / UL certificates on most of there products so I guess they know what they're doing, at least on the transformer part..

And sadly my local dealer don't carry any of the BIT range, and I suspect is there even a model for 220v+ markets? Although there are other brands but hellishly expensive, 5000 usd+ per 2KVA unit.

[amblin]

There are advantages to having your entire audio system on a single large isolation transformer. With a 240V input and 120V output. With the transformer near but not in the music room. Wire as a Separately Derived System.
Typical North American line voltages have been slowly creeping upward. Now 125V is common, so the transformer needs to be designed for well more than 125V.

Instructions in this Middle Atlantic paper. See pages 19 thru 21.

"Power Distribution and Grounding of Audio, Video and Telecommunications Equipment White Paper"
http://www.middleatlantic.com/resources/white-papers.aspx

Well ,local law require all AC electrical home appliances to be hard wired to 220V spec, so my only option is to get a 220v-220v transformer. I know nothing about electricity apart from changing bulbs.....

The typical voltage in my area is 223-225V, (standard being 220V) they say they'll include a circuit of some sort to compensate slight voltage variations and protect against unexpected surge/lighting strikes. 

And in fact my main concern is indeed unwanted interference or any anomalies that could be generated by the transformer itself.  They say proper shielding will be included and the thing will come in a steel heavy duty switch box but still , it's quite scary to have a fully charged huge donut sitting in the room...

[R. Daneel]

Be aware that big transformers like these produce quite a lot of a electromagnetic radiation so make sure you separate them from the rest of the equipment as much as possible.

Industrial transformers are always frame-type with iron-cast cores so this might be a useful advice.

Cheers!
Antun

[amblin]

Be aware that big transformers like these produce quite a lot of a electromagnetic radiation so make sure you separate them from the rest of the equipment as much as possible.

Industrial transformers are always frame-type with iron-cast cores so this might be a useful advice.

Cheers!
Antun

Yeah , this is my main concern.

Just called their engineer regarding your advice and he told me it's a single phase wiring with custom built core and he already included a copper bowl with built in cage (?) and double insulation (?) for proper shielding and the device will be installed in a seal-able steel box . in his opinion the shielding is already an overkill compaired to their regular products . And he still couldn't quite understand why exactly I'd need a 5KVA transformer in my house ....

[Speedskater]

Well that's 5KVA for resistive loads. Big power amplifiers with linear power supplies place an additional burden on the transformer.
And while 5KVA is most probably oversized, why not?
I would skip the steel box and place the transformer away from the hi-fi equipment.

[R. Daneel]

Cool! So he designed a Faraday cage for it! EM emmissions should be down to minimum then. It remains to be seen whether it will create buzzing. But I agree with your friend, it's an overkill.

You know, a colleague of mine is an electrical engineer and while transformer design is not his thing, he designs power houses for the industrial buildings we design and I always hear about his troubles with commissions of different sorts and their objections to these power houses. Apparently they have "a negative impact on nature and wildlife"! So if you hear the dogs barking, don't be surprised!

Cheers!
Antun

[amblin]

It's almost finished, some final assembly and testing then it's good to go!

[jea48]

It's almost finished, some final assembly and testing then it's good to go!

Nice looking unit.

Just curious, what size of wire are you going to feed it with?
5000VA / 220V = 22.8 amps X 125% = 28.4 amps. Minimum awg wire size would be #10awg copper. Minimum breaker size 30 amp. (Based on the National Electrical Code.)

You do understand the secondary winding of the transformer is floating above ground. You will need to intentionally connect, bond, one secondary lead of the secondary winding to the metal case enclosure cabinet housing the transformer and from the same termination point run a ground wire to earth. The intentionally grounded lead becomes the grounded neutral conductor.

Where you connect the ground wire that connects to earth depends on the safety electrical code for the country, area, you live in. You need to find out where and how it must be done.

EDIT:
One other thing that comes to mind. You should make sure the secondary output is in phase with the mains power of the main electrical service. You can do this after you have the unit powered up. If in phase if you measure voltage from the hot contact/conductor from a wall receptacle to the hot conductor from the output of the transformer unit you should measure zero nominal volts. If out of phase you will measure around 440V.

 

[amblin]

Hi Jea48

I think my dedicated line is  12AWG , originally used for air conditioning  but will it really draw that much current ?

And yes, the chassis ground is properly established via the green and white wire on the right side.  The cabinet they chose is quite nice,  with twin voltage-o-meter and three LEDs showing phase , overload and ground status.

Now I just hope it's worth the effort of dragging it across the country...

A

[jea48]

Hi Jea48

I think my dedicated line is  12AWG , originally used for air conditioning  but will it really draw that much current ?

No, it really will not draw that much current. You just limit the transformer's full potential. So why did you have a 5KV transformer built?

220V x 20 amps = 4400VA. And of course depending on how long the branch circuit is possible limit of dynamic power due to a fluctuating dynamic connected load. You can not get more power out, than the available power in.

And yes, the chassis ground is properly established via the green and white wire on the right side.  The cabinet they chose is quite nice,  with twin voltage-o-meter and three LEDs showing phase , overload and ground status.

I am not talking about a safety equipment ground, or grounding the shield of the transformer. I am talking about making the newly separately derived AC power system into a Grounded AC Power System.
One HOT ungrounded conductor.
One Grounded Conductor, the neutral conductor.

After you get it all wired up make sure you check the output for AC polarity.

*You should measure 220V nominal from the hot contact on the receptacle to the cabinet.

* You should measure zero volts from the neutral contact on the receptacle to the cabinet. 
 

[amblin]

Hi Jea48

Thanks a lot for the input, much appreciated .

There're multiple languages involved and electricity is one of great many things I'm not familiar with  so I guess there're some misunderstandings while passing info around. Their engineer said the first stage is connected to AC ground according to standard , while on the second stage it's wired to the seperate chassis ground because if it's connected to public AC ground it pretty much voids all the benefits of an 'isolation transformer' and becomes quite dangerous.

And about wires , maybe I'm wrong but I thought regardless of the actual in-wall AWG, the transformer itself will always perform and draw all the juice it needs , but if the wire continuously overloads too much it heats up and become a safety hazard , but as a conductor it'll carry as much current regardless.  And IIRC the AC sockets on most amps ,including bryston were 15A rated, while it may in theory draw 20A + but only very briefly . So if the manufactures can live with it, maybe I can as well?  Please correct me if I'm wrong.

Regards

A

[srb]

Your 12AWG circuit should be protected by a properly sized circuit breaker at the service panel or subpanel to prevent the wire from overheating, which would normally be a 20A breaker.

To keep voltage drop to a generally accepted 3% maximum, your 240V/20A circuit should have a maximum length of ~ 100ft or less, but longer runs require larger wire sizes to maintain the maximum voltage drop spec with correspondingly less resistance.

Circuits are usually derated to ~ 80% (16A) of the current for continuous loads like electric heaters, but your audio application would be far from a continuous load.  I think you'll be fine with a pair of 14Bs.

Steve

[Speedskater]

The 20 or 30 Amp breaker ratings are for continuous service, which is 3 hours or more. As 'srb' pointed out, normally de-rated to 80%. But unless you have huge Class 'A' amps the continuous current of a hi-fi system is small compared to the peak current. A typical 20 Amp breaker may allow 200 Amp continuous instantaneous current (lots of small print). Protecting the transformer circuit with a breaker smaller than the transformer's maximum rating is good engineering practice.

************
big typo

[jea48]

The 20 or 30 Amp breaker ratings are for continuous service, which is 3 hours or more. As 'srb' pointed out, normally de-rated to 80%. But unless you have huge Class 'A' amps the continuous current of a hi-fi system is small compared to the peak current. A typical 20 Amp breaker may allow 200 Amp continuous current (lots of small print). Protecting the transformer circuit with a breaker smaller than the transformer's maximum rating is good engineering practice.

A typical 20 Amp breaker may allow 200 Amp continuous current (lots of small print). Protecting the transformer circuit with a breaker smaller than the transformer's maximum rating is good engineering practice.

A typical 20 Amp breaker may allow 200 Amp continuous current

Really!? For 3 hours or more? Not typical at all.

Protecting the transformer circuit with a breaker smaller than the transformer's maximum rating is good engineering practice.

Under sizing the feeder conductors is poor engineering. Start by proving your statement by siting the NEC code article and section.
 40+ years in the commercial/industrial electrical industry I never seen an electrical equipment power riser diagram where the electrical engineer undersized the feeder conductors feeding a power transformer. NOT once! Not even when the transformer was feeding a piece of equipment where the load was known. In the case of million dollar x-ray equipment the transformer feeder was over sized, not under sized.

As for the size of the breaker protecting the feeder and primary of the transformer just going from memory NEC code minimum is 125% of the manufacture's nameplate rating up to 250% of the manufacture's nameplate rating.

To me it is a waste of a good power transformer to under size the feeder conductors. As for the load when know then size the power transformer accordingly. According to your way of the thinking the OP could have had a 10KVA transformer built and fed it from his 20 amp branch circuit and that would have been even better than the 5KVA.

[jea48]

Hi Jea48

Thanks a lot for the input, much appreciated .

There're multiple languages involved and electricity is one of great many things I'm not familiar with  so I guess there're some misunderstandings while passing info around. Their engineer said the first stage is connected to AC ground according to standard , while on the second stage it's wired to the seperate chassis ground because if it's connected to public AC ground it pretty much voids all the benefits of an 'isolation transformer' and becomes quite dangerous.

And about wires , maybe I'm wrong but I thought regardless of the actual in-wall AWG, the transformer itself will always perform and draw all the juice it needs , but if the wire continuously overloads too much it heats up and become a safety hazard , but as a conductor it'll carry as much current regardless.  And IIRC the AC sockets on most amps ,including bryston were 15A rated, while it may in theory draw 20A + but only very briefly . So if the manufactures can live with it, maybe I can as well?  Please correct me if I'm wrong.

Regards

A

Believe what you want......

For your safety.

After you get it all wired up make sure you check the output for AC polarity.

*You should measure 220V nominal from the hot contact on the receptacle to the cabinet.

* You should measure zero volts from the neutral contact on the receptacle to the cabinet.

It is unsafe to let the secondary of an isolation transformer float above ground without the proper safeguards and monitoring/supervision of qualified personnel.