I do not know how you guys that deal with MAJOR Electricity do it. When I change a outlet or a switch in the house I hit the main breaker! Lol Fricking electricity you can't see that ****. Give me a leaky pipe where I can see where the danger lies.

Kudos to those that do this sort of work!

 

We turn the power off a lot of the times too. Lol. We're not dummies.

Thank you. We need more tradesman!

 

No, I am pretty sure they meant the impedance of the transformer, not taps

I don't know about small stuff, but bigger transformers have impedance on the nameplate, and it varies by application and effects settings

I do mostly 12kv to 138, little 345, breakers, vacuum and sf6.
,transformers,disconnects, SELs. I operate and check out the equipment. Trouble shoot 125 volt dc. I have done a bit of 4kv cubicle breakers too. Distribution has got rid of it,but power plants still have it. I don't do commercial. I did some feeder sizing and prints in 90s for commercial as consultant. But have not stayed up with code.

I do outdoor breakers or cubicle , roll in breakers.

 

If I remember correctly, by changing the taps (increasing or decreasing #of windings) you effectively change the impedance of the transformer. I graduated tech school in 96. I don't remember all that math and transformer calculations past what I use on a regular basis. I don't have to do the calculations, I go get the **** put in and functioning within timeline and budget. Or I'm troubleshooting and saving someone's *** from losing a lot of money in down time.

 

A transformer in a substation has 32 taps plus neutral. It has controls to go between these taps to raise and lower voltage through the day

Basically someone picks what they want voltage to be based on length of lines, customer load, ect. It then goes up and down to stay at that voltage

It also has impedance that is measured and put on name plate. This will effect tap changer settings transformer differential settings for protection.

Different impedance ranges are chose for different applications.

The transformer at your house may or may not have taps to raise and lower voltage. But it also has an impedance too. It's not typically as big of deal. They just have some big fuses for protection.

I am not sure how much change impedance on residential transformers. But just like the big ones you can control voltage.

 

We are talking vastly different transformers. Yours are just drop in place.

 

Agreed.

Our step down transformers 480-120/208 will have different taps. It gives us the ability to adjust voltage to correct for voltage drop. So my output could be 200 and I can move it up a tap and get the desired 208-210. You're dealing automated voltage correction on the fly. Pretty cool stuff.

I have worked on current based systems (airport runway lighting). In order to maintain a constant current you adjust the voltage. The voltage can get up there pretty high. Few thousand volts. Yet we maintain 6 amps constant. It's one big loop around the entire runway with multiple transformers tapped in to power each of the lights.

I've seen a lot of ****. Only inside 1 power plant though. I was assisting an HVAC tech. I got a tour, by the HVAC tech. He worked for a contractor and couldn't explain any of the interesting stuff.

 

Worked commercial refrigeration for 38 years, was not uncommon to have a faulty breaker or disconnect that would leave one leg live after opening, I always double checked even after opening the circuit. Many commercial AC mfg's cut corners and use only a two leg brake contactor to a 3 phase comp just to save a couple bucks. You really have to be on your toes working on commercial equipment.

 

At a simple level someone decides they want 121 volts at station. The controls gets 121 pt feed to controller. Controls raise and lower taps to stay at target. Timers and settings, bands.

You can also have controllers out on line.

Pretty much all distribution has this. Some industrial customers may choose not.

But in addition, transformers have an impedance as part of how they are built

 

I’ve spent 10+ years as a field service/applications engineer in commercial LED lighting.
I’ve solved issues that teams of Edison engineers couldn’t, been shocked by touching light poles that “were off”, traveled across the country to flip a circuit breaker, and taught electricians why they shouldn’t test constant current drivers using a DVM.

The world is filled with “bad” electricians, just like it’s filled with “bad” anything else.