Terminology of bucking to recude voltage

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ronaldrc

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This is no big deal and I would rather have the auto transformer configuration.
That they are saying is produced by bucking as the name implies.

But I like to see a Duck called a Duck if it quacks like a Duck.

You get the same result either way autotransformer or bucking with the reversed winding.
But why can't they say reduced instead of buck decrease?

Study the original Buck diagrams they are Autotransformer and they are called Bucked
This is an error because the voltage reduction is being produced by reducing the windings
and not by bucking against the high voltage winding.

I think the lowered voltage should be labeled reduced instead of bucked.

To be reduced by bucking would be configured like the diagram below the red line in my diagram in the URL below.



Take a look at the Buck Boost diagrams in the 2002 NEC Handbook
page 80. Exhibit 210.18 these both the buck and boost are auto transformers
the lower one say buck, it is not it is reduced by using a lower number of turns.

Now take a look at the Exhibit 210.19 the Three Phase open Delta these
two diagrams are hooked as bucking transformers to reduce the voltage.If you will note
in the bucking one the low voltage windings are in reverse of the high voltage as they should be.

Why is it in the electrical trade everyone has too make everything confusing?Note how
they redrew the transformer again to look different instead of just relabeling the low voltage
secondary.In other words instead of H1 hooking to X4 they hook H1 to X1 so the voltages would
buck to reduce instead of add to boost.

http://home.comcast.net/~ronaldrc/wsb/Page-201.htm

Ronald :)
 
Ron, I agree that voltage reduction using a buck-boost is not genuine bucking, but it's probably more efficient using the auto-transformer method, and probably creates less heat.

Why it's called bucking I don't know. Maybe it was done that way at one point. You fit right in here by bringing this up. We love discussing theoretical stuff way past the point of reason. :)

Added: I used to think that voltage actually was reduced by bucking, by the way. Forunately, I learned the right way before I was ever assigned the task of hooking one up.
 
Last edited:
Bucking means to reduce the voltage.
Boosting means to increase the voltage.

A buck-boost transfromer can be used to buck (by connecting the incoming to the HV leads and the load to the LV leads) and also boost (by connecting the incoming to the LV leads and the load to the HV leads).

A buck-boost transformer is an isolating transfromer connected into an auto-transformer configuration which results in a relatively small voltage change (usually <20%).
 
Ronald,

I agree with you that there is a distinction between the 'autotransformer' connection and the connection where one set of windings 'bucks' the rest.

However such a 'bucking' connection could be used to raise the output voltage; simply re-arrange diagram A1 in a fashion analogous to what you did with A2.

Given that you could use either the autotransformer connection or the 'bucking' connection to either raise or lower voltage, I think that it makes more sense to use the terms buck and boost to describe what happens to the output voltage rather than to describe the particular winding connection.

-Jon
 
Thanks all for the replies

Know it has always been my reasoning to think of bucking to reduce a voltage meant to reverse the polarity and buck against another to reduce it.

If I want to reduce a voltage I think the correct way would be use the autotransformer in reverse of boosting.

When I hook a buck boost I usually just go by the diagram and not worry about how the configuration is.That way the manufactor has to back the warranty.

I just wanted to see how many would agree that, that way was not bucking to reduce the voltage. :)
 
080818-1942 EST

ronaldrc:

Buck and boost are very good terms and are supported by general dictionary definitions.

From dictionary.com

"buck" "7. to resist or oppose obstinately; object strongly to. "
When you subtract one voltage from another you have one opposing the other.

"boost" "7. an increase; rise: There's been a tremendous boost in food prices."
When you add one voltage to the another of the same polarity you increase the voltage.

If I take two separate voltage sources like a 6 V and a 1.5 V and connect these to add, then the resultant voltage is a boost from the first voltage. If I connect the 1.5 V to subtract, then I am bucking the 6 V and the output voltage is less than 6 V.

That you use an auto-transformer does not mean that the secondary can not be drawn in an equivalent circuit as a separate voltage source.

I think that buck and boost are very descriptive names and unambiguous.

Much less confusing than if I use the terms grounded conductor and grounding conductor.

.
 
Thanks Gar I agree

Of the two ways I described autotransformer reduction would be the way to go. I don't care to call it a buck decrease the term isn't right though. :)
 
I would still argue that with the 'autotransformer' connection, you are still bucking the supply voltage. Consider the transformer as a black box with terminals. Call them IN, OUT, COMMON. The voltage from OUT to IN is _bucking_ (out of phase with) the voltage from IN to COMMON, thus causing the OUT to COMMON voltage to be lower than the IN to COMMON voltage. You don't know if _internally_ one set of coils is _magnetically bucking_ any of the others, or if all the coils are 'in line' magnetically...the _voltage_ is still being bucked.

-Jon
 
The connection of the transformer windings, as either an additive or subtractive autotransformer does not matter. Once the windings are configured, you end up with a set of LV terminations and a set of HV terminations. Connect your input to the HV terminals and you will buck the voltage out of the LV terminals.

Additive and subtractive connection of the windings only affects the resulting autotransformer ratios. Given a 120:12 transformer windings, they can be connected as 120:132 or a 120:108 autotransformer.
The resulting buck-boost voltages are:
Additive windings
120 in, 132 out = 10% boost
120 in, 109 out = 10% buck
Subtractive windings
120 in, 133 out = 11% boost
120 in, 108 out = 11%buck

I have never seen a manufacturers standard wiring diagram that did not use additive winding connections
 
ronaldrc said:
This is no big deal and I would rather have the auto transformer configuration.
That they are saying is produced by bucking as the name implies.

But I like to see a Duck called a Duck if it quacks like a Duck.

You get the same result either way autotransformer or bucking with the reversed winding.
But why can't they say reduced instead of buck decrease?

Study the original Buck diagrams they are Autotransformer and they are called Bucked
This is an error because the voltage reduction is being produced by reducing the windings
and not by bucking against the high voltage winding.

I think the lowered voltage should be labeled reduced instead of bucked.

To be reduced by bucking would be configured like the diagram below the red line in my diagram in the URL below.



Take a look at the Buck Boost diagrams in the 2002 NEC Handbook
page 80. Exhibit 210.18 these both the buck and boost are auto transformers
the lower one say buck, it is not it is reduced by using a lower number of turns.

Now take a look at the Exhibit 210.19 the Three Phase open Delta these
two diagrams are hooked as bucking transformers to reduce the voltage.If you will note
in the bucking one the low voltage windings are in reverse of the high voltage as they should be.

Why is it in the electrical trade everyone has too make everything confusing?Note how
they redrew the transformer again to look different instead of just relabeling the low voltage
secondary.In other words instead of H1 hooking to X4 they hook H1 to X1 so the voltages would
buck to reduce instead of add to boost.

http://home.comcast.net/~ronaldrc/wsb/Page-201.htm

Ronald :)
Click to expand...

You too?
That term has kept me up many nights:grin:
 
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