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Automatic vs Isolated step down

Wharfedale EVO4.4

naren2512

Active Member
Joined
Nov 8, 2010
Messages
308
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Location
Mumbai
Dear Friends,

I was looking for a 1KV step down for my Onkyo 608 AVR ( US version ) and tried to look at various threads on same on HFV and and a couple more sites and learnt that :

There are mainly two type of step downs that are available in the market which can used with AVRs or other AV instruments, which are :

-- Automatic step down
-- Isolated step down

Most of the people suggest that one should go with the Isolated step down as they are safer than the Automatic ones, because :

1) If the Automatic step down goes bad it may start supplying full input current as output i,e 220 volts instead of 110 volts, while that is not the case with Isolated ones if they go bad they just stop working and dont supply any current at all to the device

2) If there is any current leakage then the Automatic one may start supplying excess current to the chassis of the step down which is a dangarous situation because if we/ our body happen to get in contact with the chassis then the current may flow down to our body, while that is not the case case with the isolated ones they do not have this risk

So I almost made my mind about the 1KV Isolated step down transformer for my AVR.

However I could not find any shop / dealer for the isolated ones in Mumbai and since Maxine has good reputation amongst various forum remembers here, I contacted them to know if they have any dealer in Mumbai and fortunately they do :) but the dealer only has automatic step downs not the isolated ones:(

I called up Maxine again and spoke to "Mr Sanjay Shah" to know if he can arrange for an Isolated 1KV for me at Mumbai he said he very well can and it will cost 6500 + freight + Taxes ( while the automatic one is cost approx 3200)

Furthermore he asked me what do I need the Isolated step down for ? I told him that I need it for my AVR on that he said that I can go for the automatic step down and its safe to be used with AV instruments and that Isolated is proffered mainly for the medical instruments/ equipments. I told him that I have read that Isolated ones are safer to be used with AVR ( for the two reason mentioned above ).

He said that they have been in this business for 40 years and for AVR its safe to go with Automatic and that there is no chance of automatic step down supplying more voltage if it goes bad as there is ( i dont remember he said mcb or fuse) which will immediately shut the step down.

Since they have such a good reputation and they themselves feel its safer to to with Automatic ones so I am not back to where I started from !!!

- Isolated or Automatic Step down ? so I thought its best to ask this question to the actual users / owners of the step downs and am sure there many on this forum who might be using step downs.

Can any gurus here and/ or the owners of the Step downs ( preferably the automatic ones) kindly share their experience ?

Has any one had any kind of problem with Automatic step down? and if so can you advise what kind of a problem ?

PS : This information will be helpful to various members including me who have to use step down with AVR or other AV instruments as it can make the choice less confusing and easier..hence I Thank you in advance for reading this and sharing your ideas / experience :)

Regards,
Naren
 

naren2512

Active Member
Joined
Nov 8, 2010
Messages
308
Points
28
Location
Mumbai
19 views but not reply yet ..!!

Guys I need your help with this topic please.....:)
 

mandeep

Active Member
Joined
Dec 8, 2007
Messages
729
Points
43
Location
Mohali (Near Chandigarh)
Dear Friends,

I was looking for a 1KV step down for my Onkyo 608 AVR ( US version ) and tried to look at various threads on same on HFV and and a couple more sites and learnt that :

There are mainly two type of step downs that are available in the market which can used with AVRs or other AV instruments, which are :

-- Automatic step down
-- Isolated step down

Most of the people suggest that one should go with the Isolated step down as they are safer than the Automatic ones, because :

1) If the Automatic step down goes bad it may start supplying full input current as output i,e 220 volts instead of 110 volts, while that is not the case with Isolated ones if they go bad they just stop working and dont supply any current at all to the device

2) If there is any current leakage then the Automatic one may start supplying excess current to the chassis of the step down which is a dangarous situation because if we/ our body happen to get in contact with the chassis then the current may flow down to our body, while that is not the case case with the isolated ones they do not have this risk

So I almost made my mind about the 1KV Isolated step down transformer for my AVR.

However I could not find any shop / dealer for the isolated ones in Mumbai and since Maxine has good reputation amongst various forum remembers here, I contacted them to know if they have any dealer in Mumbai and fortunately they do :) but the dealer only has automatic step downs not the isolated ones:(

I called up Maxine again and spoke to "Mr Sanjay Shah" to know if he can arrange for an Isolated 1KV for me at Mumbai he said he very well can and it will cost 6500 + freight + Taxes ( while the automatic one is cost approx 3200)

Furthermore he asked me what do I need the Isolated step down for ? I told him that I need it for my AVR on that he said that I can go for the automatic step down and its safe to be used with AV instruments and that Isolated is proffered mainly for the medical instruments/ equipments. I told him that I have read that Isolated ones are safer to be used with AVR ( for the two reason mentioned above ).

He said that they have been in this business for 40 years and for AVR its safe to go with Automatic and that there is no chance of automatic step down supplying more voltage if it goes bad as there is ( i dont remember he said mcb or fuse) which will immediately shut the step down.

Since they have such a good reputation and they themselves feel its safer to to with Automatic ones so I am not back to where I started from !!!

- Isolated or Automatic Step down ? so I thought its best to ask this question to the actual users / owners of the step downs and am sure there many on this forum who might be using step downs.

Can any gurus here and/ or the owners of the Step downs ( preferably the automatic ones) kindly share their experience ?

Has any one had any kind of problem with Automatic step down? and if so can you advise what kind of a problem ?

PS : This information will be helpful to various members including me who have to use step down with AVR or other AV instruments as it can make the choice less confusing and easier..hence I Thank you in advance for reading this and sharing your ideas / experience :)

Regards,
Naren
hello Naren,

I think whatever the dealer says is quite right, there is always protection against such situations.
 
Last edited:

sukhjit_bhullar

New Member
Joined
Oct 31, 2010
Messages
67
Points
0
Location
Patiala
I'm also using automatic step down and the i bought it from Chandigarh, the dealer here also assured the same thing and had told me that fuse will burn if any problem of high voltage or current. I believed him and bought it, by grace of god till date i have not faced problem.
 

naren2512

Active Member
Joined
Nov 8, 2010
Messages
308
Points
28
Location
Mumbai
@ sukhjit_bhullar

Thanks for sharing that info - I am assuming you are using the auto step down for the AVR..

Now can you also tell me what is the capacity of step down ( in watts) and since when you have been using it for your AVR ?

Also is it a branded one or a custom made step down from an electrical shop

@ Kittu

Thanks for sharing the link however that link doesnt help understand what are the practical problems with the automatic step downs hence I thought of taking view of our forum members who might be using the step downs and can probably share their experiences :)

Regards,
Naren
 

naren2512

Active Member
Joined
Nov 8, 2010
Messages
308
Points
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Location
Mumbai
@ Kittu

Thank you buddy for the link :) but i have read that too !!

I know most of the resources available on the net suggest that Isolated is better But I am just trying to know from those who are using the auto step downs, if they have been facing any problems and what kind of problems etc.

Regards,
Naren
 

borg

Active Member
Joined
Jun 24, 2010
Messages
732
Points
43
Location
cochin
are you guys talking about autotransformer based stepdown converters, there is nothing" automatic" about it. in an auto txmr there is only one winding and there is no isolated secondary like in isolation txmrs. although it is theoretically possible for an auto to pass the input to output incase of an insulation failure.practically chance of that happening is quite low, so go ahead and save some money
 

ark

New Member
Joined
Oct 18, 2010
Messages
72
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Location
Bangalore
Let me see if I can answer your queries.

Dear Friends,

1) If the Automatic step down goes bad it may start supplying full input current as output i,e 220 volts instead of 110 volts, while that is not the case with Isolated ones if they go bad they just stop working and dont supply any current at all to the device

<< If there is an open circuit on the load sharing winding of the auto transformer, then full 230V will be applied to the load , in this case your AVR. In this happens nobody can save the AVR. Enough damage will be done to the AVR's internal power supply before any auto transformer protection kicks in. And the situation could be worse if you have a higher capacity auto compared to the load. For example if you have 1KV auto and your load is only 300W , then auto is capable of supplying 3-4 times the current before it sense an over-load. This is enough to damage the AVR. The only hope is the protection present inside the AVR, mostly a simple fuse. Isolation transformer does not have this problem.


2) If there is any current leakage then the Automatic one may start supplying excess current to the chassis of the step down which is a dangarous situation because if we/ our body happen to get in contact with the chassis then the current may flow down to our body, while that is not the case case with the isolated ones they do not have this risk

<<This is not true . There is no difference between and auto and isolation transformer. if there is leakage, both will behave badly. >>

So I almost made my mind about the 1KV Isolated step down transformer for my AVR.

<< If you can afford , go for an isolation transformer which is good any day .It will also provide addition shielding from emi because there is no electrical coupling.

Compared to isolation transformer, auto transformer is cheaper, smaller in size and uses less copper and Iron. This is because one part of the load current is supplied electrically and other through induction. Auto transformer is also slightly more efficient and provides better regulation too. In my opinion, a good quality auto transformer is a good option, and the risk of getting higher voltage due to an open winding is similar to your equipment getting struck by lightning !
By the way, if you happen to use a stabilizer, you will find an auto transformer in side that too.

Regards,
Naren
 

naren2512

Active Member
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Messages
308
Points
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Location
Mumbai
Dear all,

Any owners of the step down would like to share their experience for either of the step downs.. ?

If you have been satisfied can you just share what capacity, brand and type of step down you have been using and since when ? and if you have faced any problem what kind of problem etc.

I think if every step down owner here can share their experience with step down it can definitely make it easy for our forum members (including myself) to decide on which one to go with :)

Thanks a ton for taking out time and sharing above information.

Regards,
Naren
 

snorkel4u

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Jan 10, 2011
Messages
457
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Location
Gurgaon
I am ready to join the club. Recently ordered a Denon 1911 AVR (From US) and waiting to get my hands on it. I will also be needing a step down transfer and like you, Naren, even I was suggested the isolation type transformer.

Lets hope there are more replies in this thread, @Venkatcr, he has mentioned earlier about transformers in other threads. Hope he chips in here as well.

Naren, what all are you planning to run from this transformer?

@All, do we need to consider the wattage of the AVR to buy a specific wattage transformer?
The power consumption for my AVR is around 460W as mentioned in the manual.
 

sukhjit_bhullar

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Oct 31, 2010
Messages
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Location
Patiala
@ sukhjit_bhullar

Thanks for sharing that info - I am assuming you are using the auto step down for the AVR..

Now can you also tell me what is the capacity of step down ( in watts) and since when you have been using it for your AVR ?

Also is it a branded one or a custom made step down from an electrical shop
Its 1KVA 220 to 110 step down, I bought this as my rx-v667 was rated at 400W. Well its local made not of reputed branded company, but the company name written on it is HEC.
cheers
 

naren2512

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Messages
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@ snorkel4u
As mentioned in the first post of my thread above, it will be for my AVR :)


Its 1KVA 220 to 110 step down, I bought this as my rx-v667 was rated at 400W. Well its local made not of reputed branded company, but the company name written on it is HEC.
cheers
Thanks for the info provided, can you also share the price you paid for it and whether it is an isolated one or automatic? do you get any humming sound while using Step down and since when have you been using it :)
 
Last edited:

sukhjit_bhullar

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I paid 2.5k and its a automatic step down, there is a faint humming noise when in use but i don't hear it when standing 3 feet from it with avr/speakers muted.
 

naren2512

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Messages
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Location
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I paid 2.5k and its a automatic step down, there is a faint humming noise when in use but i don't hear it when standing 3 feet from it with avr/speakers muted.
Thanks for confirming that buddy...

@ others,

Do we get humming sound from Isolated step downs of good quality as well? can any owners of isolated step downs confirm this please?

Regards,
Naren
 

alexanish

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Feb 9, 2011
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Location
Bangalore
naren,

I have an isolation type but no sound. Mine I got from a local transformer maker - custom made.

Snorkel,

The power consumption is what I have looked for before buying the transformer. For me it is 6Amp which is roughly 720 watts. So I bought a 750watt one. Running just fine.

Thanks!
Anish
 

snorkel4u

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nice.... hows ur 608 running on it? With the velodyne sub it must be sounding awesome am Sure.

Where did you get this one made in Bangalore? How much did it cost? I have family in Blore and can try and procure the transformer from there.....

Did you get it checked with a multimeter, as to whats the O/P voltage?
 

alexanish

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Feb 9, 2011
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Location
Bangalore
It's close to theater when I play movies :)

I usually turns the volume to 68 to 75(max). At these levels the transformer has still little more capacity left. So it never goes hot.

I got it done from Universal transformers in SP road which is a local electronic/electrical equipment sellers area. You should also be able to find such a place near by you or approach any good transformer makers who knows what isolation type is and make sure they do make it regularly. For me the 750watt cost 4500. Carrying it from bangalore is not that easy task as the unit is quite heavy.

The sellers while delivering shown me the capacity using multimerter. The meter showed both input(230) and out put(110) volts. The unit itself has an input volt meter but no output meter.
 
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