In rush current is a small benefit. The real benefit is you can produce the exact voltage you need.
Are isolation transformers a lot more expensive than a power transformer?
If so then the cost of both the variac and the isolation transformer will be far more than just the power transformer. Plus the isoliation transformer will take up more space too. I do not know how large isolation transformers are.
But, I do not see why the variac does not provide isolation by itself. Its just an adjustable power transformer?
Are isolation transformers a lot more expensive than a power transformer?
If so then the cost of both the variac and the isolation transformer will be far more than just the power transformer. Plus the isoliation transformer will take up more space too. I do not know how large isolation transformers are.
But, I do not see why the variac does not provide isolation by itself. Its just an adjustable power transformer?
No, you can't.
I've been thinking about it too, but it is also very unlikely when you think about it.
If you want for example have a 10V ac, and using it for lots of current, you only use a little part of the variac, from wich the power it less.
Instead if you turn it up at full, it can dissipate more warmth, then setting it on half or less.
You need a (very) big variac to do this.., I've got a 2KVA variac (220ac) but I'm not gonna try it out. Just buy a regular transformer.
For example, if you use a variac, you can go from a aleph 3 (out of head 25V rail?) to a aleph 2 or 1.2!!
Hope I explained it a little bit.
Any comments welcome!
Remco
I've been thinking about it too, but it is also very unlikely when you think about it.
If you want for example have a 10V ac, and using it for lots of current, you only use a little part of the variac, from wich the power it less.
Instead if you turn it up at full, it can dissipate more warmth, then setting it on half or less.
You need a (very) big variac to do this.., I've got a 2KVA variac (220ac) but I'm not gonna try it out. Just buy a regular transformer.
For example, if you use a variac, you can go from a aleph 3 (out of head 25V rail?) to a aleph 2 or 1.2!!
Hope I explained it a little bit.
Any comments welcome!
Remco
Now Say After Me, "Auto-transformer"....
"But, I do not see why the variac does not provide isolation by itself. Its just an adjustable power transformer?"
No, no, no.
A variac is an autotransformer, which means a single winding with a wiper, and hence no DC isolation.
I hope you undersatand the danger in that.
Eric.
"But, I do not see why the variac does not provide isolation by itself. Its just an adjustable power transformer?"
No, no, no.
A variac is an autotransformer, which means a single winding with a wiper, and hence no DC isolation.
I hope you undersatand the danger in that.
Eric.
"And its best to use the variac to test designs."
And repairs too.
I use a variac with a lamp (40, 60 or 100W) in series with the primary, and this is a perfect tool for running up repaired equipment, especially amplifiers.
If there is a fault, the lamp glows and dissipates most of the power, and low voltage only is available to the device under test.
Eric.
And repairs too.
I use a variac with a lamp (40, 60 or 100W) in series with the primary, and this is a perfect tool for running up repaired equipment, especially amplifiers.
If there is a fault, the lamp glows and dissipates most of the power, and low voltage only is available to the device under test.
Eric.
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