A 110v surge protector instead of isolation transformers ?

[vinayaga]

I have been reading up a lot on step down transformers since I intend to get a Pioneer receiver from the US and am looking to see how to get a good deal.

Almost every thread on this in hifivision has details on how to get the best transformer and more importantly, to get isolation type transformers. Comments like these abound : You need to get "Isolation Type" Step down Transformers. Now the reason given for getting a isolation type transformer is that the normal transformers can go bad and start supplying 240v directly instead of converting the voltage, thus bringing down the entire system.

Im thinking, how about getting a normal good brand (Maxine ?) transformer of 1kw/Rs 1k and take the output of the transformer into a US surge protector ($10) and then pass the output of the surge protector to the AV receiver. A good US surge protector comes with ample guarantees of coping with high voltages. So if the cheapo transformer does go bad and supplies more than 120v, the surge protector will kick in and protect the attached device.

Obviously, I could be missing something fundamental here in this line is thinking since folks spend 3-5k on isolation transformers. So Gurus, what am I missing here technically ? Can a surge protector NOT work with a transformer ? Any holes in the theory ?

 

[vinayaga]

Just so it is clear, the idea is not to save money. The idea is to get the maximum and guaranteed protection even if I spend obscene amount of money.

On that note, how about something like this between the transformer and the receiver ?

NEW APC Line-R 1200VA Line Conditioner With AVR LE1200 (Rs. 3757)

 

[ark]

I have been reading up a lot on step down transformers since I intend to get a Pioneer receiver from the US and am looking to see how to get a good deal.

Almost every thread on this in hifivision has details on how to get the best transformer and more importantly, to get isolation type transformers. Comments like these abound : You need to get "Isolation Type" Step down Transformers. Now the reason given for getting a isolation type transformer is that the normal transformers can go bad and start supplying 240v directly instead of converting the voltage, thus bringing down the entire system.

Im thinking, how about getting a normal good brand (Maxine ?) transformer of 1kw/Rs 1k and take the output of the transformer into a US surge protector ($10) and then pass the output of the surge protector to the AV receiver. A good US surge protector comes with ample guarantees of coping with high voltages. So if the cheapo transformer does go bad and supplies more than 120v, the surge protector will kick in and protect the attached device.

Obviously, I could be missing something fundamental here in this line is thinking since folks spend 3-5k on isolation transformers. So Gurus, what am I missing here technically ? Can a surge protector NOT work with a transformer ? Any holes in the theory ?

Ok , let me see if I understood your question.

First question : All transformers are isolation type transformers. The only exception is the auto transformer. So when you say normal good brand ( Maxine) transformer , are you referring to an auto transformer or a regular one ?

Second question : If the auto transformer secondary becomes an open circuit, full 230V will be applied to the load . Surge protector cannot help here. These protectors are designed to take care of surges, which is short burst of high voltage energy. They cannot continuously dissipate the 220V applied. So what would happen is first the surge protector will get fried and then your electronics.

 

[vinayaga]

1. I do mean the Auto transformer.

2. The good surge protectors come with a auto trip switches, at least the belkin ones I own have them. If there is any surge, temporary or permanent, the surge protector immediately trips and shuts down current from passing. Will this not solve the purpose ?

Im not trying to debate as my knowledge is limited with electricals, but I sure want to understand where Im goiung wrong here.

Ok , let me see if I understood your question.

First question : All transformers are isolation type transformers. The only exception is the auto transformer. So when you say normal good brand ( Maxine) transformer , are you referring to an auto transformer or a regular one ?

Second question : If the auto transformer secondary becomes an open circuit, full 230V will be applied to the load . Surge protector cannot help here. These protectors are designed to take care of surges, which is short burst of high voltage energy. They cannot continuously dissipate the 220V applied. So what would happen is first the surge protector will get fried and then your electronics.

 

[captrajesh]

I wonder why many such threads go un-participated while some have extra ordinary participation. I'm not sure of the possibility of a transformer going bad and supply the same voltage that is inputted.

 

[Hiten]

Never Use a Surge Protector with a Step-Down Transformer

 

[captrajesh]

Never Use a Surge Protector with a Step-Down Transformer

Pretty interesting information there Hiten.

 

[vinayaga]

Wow, this is something interesting. But unfortunately, this is how folk tales start :sad: Now every person who reads this heading and link is going to claim that you should never use a surge protector with a transformer !!!

The point to note is that the transformer in the article is one that is more available in the US and Europe, it is a two way transformer that can do 110v to 220v or 220v to 110v. So yes, the circuitry will be a lot more complicated and will need to reuse the same channel to achieve either step up or down based on the setting.

In our cases, the simple transformers only do step down, so it is a lot simpler. And a surge protector will come handy, would rather have the $5 surge protector burn up than have my receiver burn

Also, in the article, I do not see how this is a realistic scenario. The author claims that the ground and neutral combination provides the full 220v. Now how is it possible for a person to insert the plug in such a way so that one of them gets into the ground socket of the surge protector ?

Never Use a Surge Protector with a Step-Down Transformer

 

[Hiten]

The point to note is that the transformer in the article is one that is more available in the US and Europe, it is a two way transformer that can do 110v to 220v or 220v to 110v.

Sorry I don't know how a SINGLE Primary winding with tap for 110 V output can take 110v input and step UP to 220V.

In our cases, the simple transformers only do step down,

Kindly explain simple transformer. Is it Primary winding with tap for 110v or Primary and secondary where secondary winding gives 110v. If I remember correctly normally Primary winding doing step down have thin wire with more number of turns than secondary and are isolated from each other with insulating varnish and are not touching each other. So are recommended.
Regards

 

[vinayaga]

I do not know how a SINGLE primary winding can do that, but if you look into amazon for many of the auto transformers, they are dual purpose and can either step up or down. (Hope Im not mistaken, but the description clearly says so)

Sorry I don't know how a SINGLE Primary winding with tap for 110 V output can take 110v input and step UP to 220V.

Kindly explain simple transformer. Is it Primary winding with tap for 110v or Primary and secondary where secondary winding gives 110v. If I remember correctly normally Primary winding doing step down have thin wire with more number of turns than secondary and are isolated from each other with insulating varnish and are not touching each other. So are recommended.
Regards

I meant the auto transformer when I said simple transformer. As you can obviously see, Im a novice when it comes to electricals !

 

[Hiten]

Auto transformer must be having switchable input, but still a single winding so would be risky with protection of only a variastor (Which can get shorted) of surge protector. May be pros of electrical knowledge would elaborate further.
Regds.

 

[borg]

auto tfr can be designed with both stepup and stepdown modes, and is perfectly reliable and its comparatively lower leakage inductance will help the avr dynamic requirements.

Why not get a surge suppressor rated 220v and put at the input of the transformer,(mains supply) there is no need for a 110v surge suppressor

 

[vinayaga]

Well, Im doing exactly that to cover my base on both sides. A 220v surge protector at the front and a 110v surge protector at the other end and connect it to the Receiver. Hopefully, nothing will blow up for a few years

auto tfr can be designed with both stepup and stepdown modes, and is perfectly reliable and its comparatively lower leakage inductance will help the avr dynamic requirements.

Why not get a surge suppressor rated 220v and put at the input of the transformer,(mains supply) there is no need for a 110v surge suppressor

 

[Hiten]

Why not get a surge suppressor rated 220v and put at the input of the transformer,(mains supply) there is no need for a 110v surge suppressor

Yeah that makes sense. And wouldn't it be safe to replace two pin wire with three pin plug so as not to interchange live and neutral wire accidentally ?

 

[venkatcr]

Vinayaga, if you 'condition' the 220 volts input to the step down, you really need not do anything after that. The step down by itself cannot create a surge. Surges come from the carrier that carry anywhere between 220 to 11,000 volts. When there is sudden cut off of usage, there is a momentary surge in the rest of the circuits. This is just one of the many reasons. If you are looking for protection against lightning strikes, as I have mentioned many times before, there is none.

A good voltage regulator will send a protected 220 volts to the step down. This can have surge, RFI, and EMI protection. In India, this is easier to do as there are not too many 110 volts protection units available here.

All the step down has to do after that is to convert it to 110 volts.

Cheers

 

[vinayaga]

I got my Maxine Auto transformer today and it looks neat. Has a Three pin plug for both input and output, more importantly has two fuse, one trip for output and one normal 5a plug type fuse for input .

Strangely, they have two outputs, one marked 100v and another marked 110v. Is the 100v output to cover sensitive equipment that should never cross 110v ? Which should I use ?

 

[vinayaga]

Thanks so much for the inputs. This was explained well in layman's language !!! So a good 220v voltage stabilizer in front of the transformer should do the trick and nothing more is needed ?

Vinayaga, if you 'condition' the 220 volts input to the step down, you really need not do anything after that. The step down by itself cannot create a surge. Surges come from the carrier that carry anywhere between 220 to 11,000 volts. When there is sudden cut off of usage, there is a momentary surge in the rest of the circuits. This is just one of the many reasons. If you are looking for protection against lightning strikes, as I have mentioned many times before, there is none.

A good voltage regulator will send a protected 220 volts to the step down. This can have surge, RFI, and EMI protection. In India, this is easier to do as there are not too many 110 volts protection units available here.

All the step down has to do after that is to convert it to 110 volts.

Cheers

As for the 110v surge, I actually had one lying in the house and hense thought I would use it !

 

[venkatcr]

Strangely, they have two outputs, one marked 100v and another marked 110v. Is the 100v output to cover sensitive equipment that should never cross 110v ? Which should I use ?

You should carefully look at the input range specified in your unit and use that. Most units will handle a +/- 10 volts without issue.

Cheers

 

[venkatcr]

As for the 110v surge, I actually had one lying in the house and hense thought I would use it !

Adding too many 'protection' devices between the source and the units is not a good idea. Decide what you need to control and do it once.

Cheers

 

[Deepchand]

What if the AVR's requirements are 120 volts at 60 HZ. Are there different converters to output 120v? Also, we know that power supplied in India is at 50 HZ, can anything be done about that too?

TIA