Good morning Robert! That is actually the nameplate of the padmount transformer serving my home. It's hiding in some decorative grass across the street. So, your questions
The impedance ratings on the nameplate of every transformer of any significant size made. It is basically the internal impedance rating of the transformer, it has a temperature because impedance changes as temperature changes. It has a effect of transformer efficiency, but it's primarily used to calculate the secondary available fault current. If you look at you house panel it is rated for a maximum fault current it can handle, usually 10KA. The fault current is important in big industrial boards because if the available fault current is higher than the board rating, the circuit breakers can explode trying to open on a short circuit. You can buy higher fault current rated residential boards.
Subtractive polarity only matters if you want to run transformers in parallel. But if you parallel a subtractive polarity and an additive polarity they will blow up. It speaks to how the voltage behaves if you hooked the primary and secondary winding in series.
There are two primary connections because it is fed by underground cable, the second terminal allows the underground loop to continue to the next transformer down the line. These connections are made with special plug in load break elbows.
There are two fuse, one accessible to the lineman, one backup fuse deep inside the transformer tank. The lineman can pull the one fuse to turn off the transformer, or replace it. If the backup fuse blows the transformer is replaced and considered trash.
This brings back memories for me when I worked at Commonwealth Edison in Chicago in the late 70’s. At that time the advent of SF6 insulated substations for inner city use with HV underground distribution as much as 138 kv. Of course, now we know that SF6 is bad for the upper atmosphere and toxic to life, etc.
Thank's KVar, another important link in your very helpful series, and about as simple as you can get (the analogy of our roads and transport systems will be great for some folks). Yes, some readers will find this way too simple but, if they do, then they already know a lot more than the average person, and need to take a step back.
As my colleagues and I have learned in this game, it is always going to be very risky to try keeping some things simple, because your efforts will always be unsatisfactory to some people at either end of the spectrum. You hit the mark for old powergen' blokes like us.
I guess the photo'd tag is from a typical, pole-mounted transformer to a home. What does 2.3% imp 85°C mean? What is subtractive polarity? Why two primary side connections, and why two fuses in series?
Good morning Robert! That is actually the nameplate of the padmount transformer serving my home. It's hiding in some decorative grass across the street. So, your questions
The impedance ratings on the nameplate of every transformer of any significant size made. It is basically the internal impedance rating of the transformer, it has a temperature because impedance changes as temperature changes. It has a effect of transformer efficiency, but it's primarily used to calculate the secondary available fault current. If you look at you house panel it is rated for a maximum fault current it can handle, usually 10KA. The fault current is important in big industrial boards because if the available fault current is higher than the board rating, the circuit breakers can explode trying to open on a short circuit. You can buy higher fault current rated residential boards.
Subtractive polarity only matters if you want to run transformers in parallel. But if you parallel a subtractive polarity and an additive polarity they will blow up. It speaks to how the voltage behaves if you hooked the primary and secondary winding in series.
There are two primary connections because it is fed by underground cable, the second terminal allows the underground loop to continue to the next transformer down the line. These connections are made with special plug in load break elbows.
There are two fuse, one accessible to the lineman, one backup fuse deep inside the transformer tank. The lineman can pull the one fuse to turn off the transformer, or replace it. If the backup fuse blows the transformer is replaced and considered trash.
Let me know if that answered your questions.
This brings back memories for me when I worked at Commonwealth Edison in Chicago in the late 70’s. At that time the advent of SF6 insulated substations for inner city use with HV underground distribution as much as 138 kv. Of course, now we know that SF6 is bad for the upper atmosphere and toxic to life, etc.
Thank's KVar, another important link in your very helpful series, and about as simple as you can get (the analogy of our roads and transport systems will be great for some folks). Yes, some readers will find this way too simple but, if they do, then they already know a lot more than the average person, and need to take a step back.
As my colleagues and I have learned in this game, it is always going to be very risky to try keeping some things simple, because your efforts will always be unsatisfactory to some people at either end of the spectrum. You hit the mark for old powergen' blokes like us.
I guess the photo'd tag is from a typical, pole-mounted transformer to a home. What does 2.3% imp 85°C mean? What is subtractive polarity? Why two primary side connections, and why two fuses in series?