Excellent video!! Thank you so much! Only thing missing from those would be the polarity dots but other than that this was exactly what I was looking for!
I understood but little bit confusing near the addition and subtraction and i have a doubt that y u have mentioned the H1 and x1 crossly in addition and comming to subtraction u mentioned it in vertical and why..??
What determines the letters H1 H2 and X1 X2? In both your depictions all we can see is that you draw H1 and X1 adjacent to eachother and H1 and X1 crossed from one another, but what about the windings in an actual transformer determines which letter goes where?
So I work in HVAC. This finally made it click why so many manufacturers bond the secondary side of the transformer to ground on the side they designate as common.
Another question, what’s with the red line connection that you make between the primary and secondary? I thought transformers are separately derived systems with no conductive path connecting primary to the secondary, but rather operate via mutual inductance.
Very good video! How does polarity work on a distribution transformer when the windings are split (like two 120v windings) X3, X2, X1? This is how most standard transformers are wired for distribution voltages to feed a house, 120, 120, 240V.
You still have to think of it as one winding. If X1 is negative and X2 is positive, this would yield a -120v (for algebraic addition). X2 to X3, now X2 becomes the negative, with respect to X3 (as this is the most positive point in the circuit) giving us another -120v. These added together would equal the potential across the whole secondary coil of 240v.
Another great video thank you. One point you were trying to make is why we care. Well if we’re just trying to figure out whether a transformer is add or sub then this video nailed it. At the end you said we care because it’ll impact your overall voltage. But to go a little further, can you explain when it comes to our connections, paralleling transformers, or building banks, what can happen if polarity is incorrect? Can you parallel an add and sub transformer on the same phase? Can you bank 2 adds and 1 sub without changing the positions of your secondary leads? I have been told what you can and cannot do, but actually seeing it on paper, seeing why you can or cannot, what can happen, etc. would be great! And you do a terrific job at explaining it on paper if you get what I’m saying. Thank you again.
In a lab environment what do I change about my circuit to make it additive or subtractive? As I understand it the magntic flux travelling through the iron core should always make it additive no? unless of course you have another voltage source on the other (secondary) coil which would try to flow against the flux induced by the primary coil. But then what's the point of a transformer if you have voltage sources on both sides? and wouldn't this break the step-up/step-down nature of the transformer?
Basically you flip the connection on the secondary coil when connecting them together in series in an auto transformer configuration. This gives you additional voltage options, and can be used also as a boost if connecting additively, for example
@@schulerruler I found a text based explanation it says that if both solenoids are wound counter clockwise or clockwise it will be subtractive. If 1 solenoid is clockwise and the other is counter clockwise then it's additive. My only confusion is as to how the direction the solenoid is coiled impacts the polarity. Surely the only thing that should impact this is the direction the current and magnetic flux travels through the wire/core and not the way the wire is wound....
We're really looking at a snapshot in time when we analyze an AC circuit. Realistically the polarity would switch on a terminal at the rate of the frequency.
I didn't understand the part where you mention that terminals with odd numbers are negative and even numbers are positive. Because from left to right you have H1to H2 to X2 to X1. That would be negative to positive to negative to positive how did you get -120 minus -12v. Please help me understand this..
If we place a negative value on the odd terminals, and a positive value on the even and write out mathematically the formula it would be (-120v) + (+12v) = -108v, or better said, 108v of potential.
Good explanation of the topic but I don't really know what this is about. This method is a topic in the CEC pocket reference too so I know it's important but I don't understand the context in which this test would be done?
Often if you are paralleling transformers for higher capacity, connecting in series (multiwinding transformers) or creating an autotransformer situation you will need to ensure that the polarity of the terminals is designated for correct voltage applications.
The voltage stress from high voltage side to low voltage side in a subtractive transformer is lower,hence subtractive transformer. Now on a 200 Kva or higher transformer the amount of energy delivered during an internal fault would result in a lower energy (kw) fault. Lower kw lower destruction of the transformer. It doesn’t matter in our distribution transformers 12000v/240v. Higher voltage transformers is where you would see high appreciable difference. Example 115kv /66kv additive transformers the voltage stress would be 181kv x 1000amp internal fault would result in a 181,000kw fault. If they were subtractive the voltage stress would be 49kv x 1000amp internal fault would result in a 49,000kw fault. Being wound subtractive over 1/3rd less damage and therefore a lot less money to repair the transformer. Remember when it comes to higher voltage transformers we repair not replace if at all possible.
Good explanation, but why is considered additive only to a certain voltage, for example in single phase pad transformers more than 24940y/14400 is considered subtractive?
Ok, so why or when does this matter? Functionally, if I have 120 on my primary and 12 on my secondary and the transformer is connected NORMALLY then the transformer is doing what I need it to do, supply 12vac to my load. I'm sure I'm missing something, please give an example of when this is useful.
This would be if you were connecting the transformer as an autotransformer and either "bucking" or "boosting" the voltage. You are correct in the statement that when using this as a conventional transformer, it is not something that's an issue.
Think about it in terms of line and neutral at an electrical outlet. The neutral wire is attached at the center point of the house's supply transformer, and is bonded to ground at the main service panel. For all intents and purposes, it's your reference point for all circuits in the house. Say you then plug in this transformer. If you read from one side of the secondary coil to ground, you get approximately 6V, and the other side reads approximately 3V. This is because the primary side of the transformer is run between the reference point and one hot leg, instead of between two hot legs. I would equate it to the difference between pulling one end of a spring with the other attached to an anchor point and pulling on both ends of it. In the case of HVAC, which is my field, it messes with the flame rectification if you get the hot and neutral wires backwards coming into the furnace. Basically the point of flame rectification is to detect whether there's a flame present, and if not present, shut off the furnace. This works because electrons have an easy time flowing from the flame sensing rod to the metal frame of the furnace, but not the other way around. The furnace board detects this as a DC current pulsing at 30Hz, and keeps the furnace in operation. Since the neutral is the reference point and is attached to ground, if you get the polarity backwards then the flame rectification doesn't work right. You don't get anywhere near the same signal strength, and the board can't tell if there's a flame. In fact, most modern furnaces bond the common side (the side that reads 1/2 voltage to ground when disconnected) of the transformer to ground directly, in which case you get no current flowing through the flame at all if the polarity is reversed. But most modern furnaces actually can detect the polarity and the board will give you an error code telling you it's backwards.
what book do you use ? I have never seen H X terminals( very confusing to me ) the good books always use "DOT Convention" . DOT placement is crucial to get started , then the interpretation and equation writing is simple KVL with Ohm's law . You made a fixed tap Auto Transformer . ISBN : 0-07-027410-X Engineering Circuit Analysis Fifth Edition 1993 ( everyone should read that book )
This is the IEEE standard for transformer terminal designations. The High voltage side is designated by capital H followed by the subscript number of the terminal (ex H1 H2 etc). The lower voltage side is indicated by capital X and terminal number. Any transformer I have ever terminated has had the H and X teminal markings. Instrument Transformers are commonly marked with a white dot to indicate that this is H1.
@@schulerruler aah ,... I was looking for , or in the mind set of "Coupled Coils" that work with Mutual inductance and using the DOT Convention . Context ,...I stumbled onto something slightly different . As long as I am here ,...is there a "connection\similarity" of use , to associate the DOT Convention of DOT placement , to that of the H and X terminals ? A DOT does not necessarily depict a Higher or Lower voltage side . or , is this an Apples\Oranges situation ?
@@240mains from what I understand, and this is from limited knowledge of instrument Transformers used for revenue metering, the white dot will always represent the H1 terminal, while the x1 terminal may or may not also have a white dot. This is how we generally introduce autotransformers is with standard mutual induction Transformers, and then reconnecting them as a step up or step down auto.
Thanks again for making these videos. Nice, concise and clear. Really appreciated
Excellent video!! Thank you so much! Only thing missing from those would be the polarity dots but other than that this was exactly what I was looking for!
Awesome. I'm happy it helped. Thanks for watching!
Addition or subtractive hook up. What effect does it have on the load side of the transformer? What effect does it have on the transformer
I understood but little bit confusing near the addition and subtraction and i have a doubt that y u have mentioned the H1 and x1 crossly in addition and comming to subtraction u mentioned it in vertical and why..??
What determines the letters H1 H2 and X1 X2? In both your depictions all we can see is that you draw H1 and X1 adjacent to eachother and H1 and X1 crossed from one another, but what about the windings in an actual transformer determines which letter goes where?
So I work in HVAC. This finally made it click why so many manufacturers bond the secondary side of the transformer to ground on the side they designate as common.
Another question, what’s with the red line connection that you make between the primary and secondary? I thought transformers are separately derived systems with no conductive path connecting primary to the secondary, but rather operate via mutual inductance.
Hello When you apply 120 V do you put just on the H1 or do you apply the 120v to the H1 and H2 at the same time
Very good video! How does polarity work on a distribution transformer when the windings are split (like two 120v windings) X3, X2, X1? This is how most standard transformers are wired for distribution voltages to feed a house, 120, 120, 240V.
You still have to think of it as one winding. If X1 is negative and X2 is positive, this would yield a -120v (for algebraic addition). X2 to X3, now X2 becomes the negative, with respect to X3 (as this is the most positive point in the circuit) giving us another -120v. These added together would equal the potential across the whole secondary coil of 240v.
Thanks a lot for the helpful videos, hope you will make a video on transformer vector groups.
Another great video thank you. One point you were trying to make is why we care. Well if we’re just trying to figure out whether a transformer is add or sub then this video nailed it. At the end you said we care because it’ll impact your overall voltage. But to go a little further, can you explain when it comes to our connections, paralleling transformers, or building banks, what can happen if polarity is incorrect? Can you parallel an add and sub transformer on the same phase? Can you bank 2 adds and 1 sub without changing the positions of your secondary leads? I have been told what you can and cannot do, but actually seeing it on paper, seeing why you can or cannot, what can happen, etc. would be great! And you do a terrific job at explaining it on paper if you get what I’m saying. Thank you again.
In a lab environment what do I change about my circuit to make it additive or subtractive?
As I understand it the magntic flux travelling through the iron core should always make it additive no? unless of course you have another voltage source on the other (secondary) coil which would try to flow against the flux induced by the primary coil.
But then what's the point of a transformer if you have voltage sources on both sides? and wouldn't this break the step-up/step-down nature of the transformer?
Basically you flip the connection on the secondary coil when connecting them together in series in an auto transformer configuration. This gives you additional voltage options, and can be used also as a boost if connecting additively, for example
@@schulerruler I found a text based explanation it says that if both solenoids are wound counter clockwise or clockwise it will be subtractive.
If 1 solenoid is clockwise and the other is counter clockwise then it's additive.
My only confusion is as to how the direction the solenoid is coiled impacts the polarity. Surely the only thing that should impact this is the direction the current and magnetic flux travels through the wire/core and not the way the wire is wound....
Clear explanation, but what makes. the polarity stay constant? Thank you.
We're really looking at a snapshot in time when we analyze an AC circuit. Realistically the polarity would switch on a terminal at the rate of the frequency.
@@schulerruler at every half cycle of the frequency.
True enough.
I didn't understand the part where you mention that terminals with odd numbers are negative and even numbers are positive. Because from left to right you have H1to H2 to X2 to X1. That would be negative to positive to negative to positive how did you get -120 minus -12v. Please help me understand this..
If we place a negative value on the odd terminals, and a positive value on the even and write out mathematically the formula it would be
(-120v) + (+12v) = -108v, or better said, 108v of potential.
Can you explain voltage regulators? Like this?
Do you mean like from no load to full load voltage regulation for Transformers?
Good explanation of the topic but I don't really know what this is about. This method is a topic in the CEC pocket reference too so I know it's important but I don't understand the context in which this test would be done?
Often if you are paralleling transformers for higher capacity, connecting in series (multiwinding transformers) or creating an autotransformer situation you will need to ensure that the polarity of the terminals is designated for correct voltage applications.
@@schulerruler oh okay, so like if you were trying to make a three phase transformer out of three (equivalent) single phase ones?
@@josho5177 That is a great example.
@@schulerruler sweet, thanks, the visuals are looking good btw! Audio nice levels too
Yes, but why does the single phase step down transformer OVER 200 KVA NEED a subtractive transformer? thank you
The voltage stress from high voltage side to low voltage side in a subtractive transformer is lower,hence subtractive transformer. Now on a 200 Kva or higher transformer the amount of energy delivered during an internal fault would result in a lower energy (kw) fault. Lower kw lower destruction of the transformer. It doesn’t matter in our distribution transformers 12000v/240v. Higher voltage transformers is where you would see high appreciable difference. Example 115kv /66kv additive transformers the voltage stress would be 181kv x 1000amp internal fault would result in a 181,000kw fault. If they were subtractive the voltage stress would be 49kv x 1000amp internal fault would result in a 49,000kw fault. Being wound subtractive over 1/3rd less damage and therefore a lot less money to repair the transformer. Remember when it comes to higher voltage transformers we repair not replace if at all possible.
good explanation of transformer polarity. Thanks
Good explanation, but why is considered additive only to a certain voltage, for example in single phase pad transformers more than 24940y/14400 is considered subtractive?
8660v or greater or 200kva or greater it will be wound subtractive.
Ok, so why or when does this matter? Functionally, if I have 120 on my primary and 12 on my secondary and the transformer is connected NORMALLY then the transformer is doing what I need it to do, supply 12vac to my load. I'm sure I'm missing something, please give an example of when this is useful.
This would be if you were connecting the transformer as an autotransformer and either "bucking" or "boosting" the voltage.
You are correct in the statement that when using this as a conventional transformer, it is not something that's an issue.
Think about it in terms of line and neutral at an electrical outlet. The neutral wire is attached at the center point of the house's supply transformer, and is bonded to ground at the main service panel. For all intents and purposes, it's your reference point for all circuits in the house. Say you then plug in this transformer. If you read from one side of the secondary coil to ground, you get approximately 6V, and the other side reads approximately 3V. This is because the primary side of the transformer is run between the reference point and one hot leg, instead of between two hot legs. I would equate it to the difference between pulling one end of a spring with the other attached to an anchor point and pulling on both ends of it.
In the case of HVAC, which is my field, it messes with the flame rectification if you get the hot and neutral wires backwards coming into the furnace. Basically the point of flame rectification is to detect whether there's a flame present, and if not present, shut off the furnace. This works because electrons have an easy time flowing from the flame sensing rod to the metal frame of the furnace, but not the other way around. The furnace board detects this as a DC current pulsing at 30Hz, and keeps the furnace in operation.
Since the neutral is the reference point and is attached to ground, if you get the polarity backwards then the flame rectification doesn't work right. You don't get anywhere near the same signal strength, and the board can't tell if there's a flame. In fact, most modern furnaces bond the common side (the side that reads 1/2 voltage to ground when disconnected) of the transformer to ground directly, in which case you get no current flowing through the flame at all if the polarity is reversed. But most modern furnaces actually can detect the polarity and the board will give you an error code telling you it's backwards.
you are the best man thanks.
Thank you for the support!
Absolutely informative, Thanks a lot !
what book do you use ?
I have never seen H X terminals( very confusing to me )
the good books always use "DOT Convention" . DOT placement is crucial to get started , then
the interpretation and equation writing is simple KVL with Ohm's law .
You made a fixed tap Auto Transformer .
ISBN : 0-07-027410-X Engineering Circuit Analysis Fifth Edition 1993 ( everyone should read that book )
This is the IEEE standard for transformer terminal designations. The High voltage side is designated by capital H followed by the subscript number of the terminal (ex H1 H2 etc). The lower voltage side is indicated by capital X and terminal number.
Any transformer I have ever terminated has had the H and X teminal markings. Instrument Transformers are commonly marked with a white dot to indicate that this is H1.
@@schulerruler aah ,... I was looking for , or in the mind set of "Coupled Coils" that work with Mutual inductance and using the DOT Convention . Context ,...I stumbled onto something slightly different .
As long as I am here ,...is there a "connection\similarity" of use , to associate the DOT Convention of DOT placement , to that of the H and X terminals ? A DOT does not necessarily depict a Higher or Lower voltage side . or , is this an Apples\Oranges situation ?
@@240mains from what I understand, and this is from limited knowledge of instrument Transformers used for revenue metering, the white dot will always represent the H1 terminal, while the x1 terminal may or may not also have a white dot.
This is how we generally introduce autotransformers is with standard mutual induction Transformers, and then reconnecting them as a step up or step down auto.
thanku sir
Thanks for watching!