Transformer sizing

[ruxton.stanislaw]

Right, but doesn't the ban on gas powered leaf blowers also apply to residential users?

What if they use a gas generator with an extension cord to the power tools...?

 

[guytrinidad]

these guys do lawn maintenance for cities, county's, and big industrial and commercial buildings. with 100's of employees, Im not looking for ways to change the way they use or power their tools Im looking for help on sizing a loadcenter and transformer, I understand everybody has their own opinion on topics like this but its not helping me by trying to explain why or what they do, I do appreciate the advise I am getting on this site.

 

[LarryFine]

Guy, for the most part, it's not meant as criticism, but clarification to provide accurate and useful answers.

I am a literalist, and tend to give simple and direct answers to questions as asked, presuming the asker knows what wasn't asked. Many forum members delve more deeply and ask for more details before answering.

 

[guytrinidad]

Thank you for the reply, Larry. And I do really knows that. But I was trying to envision a guy riding a lawn mower. Mowing the lawn in a city park pulling a generator that his lawn mower was plugged into, it was a funny thought I will have to admit. I do understand that, I started out lacking a bit of information and left a lot of people guessing. And I also had some misinformation to start out with also,I know that as an electrical contractor, mainly a installer for the last 35 years. I don't really have the knowledge that the electrial engineer Or a master electrician that has been doing the formulas and calculations on a daily base to complete commercial and industrial jobs, And that is my downfall, I will have to admit it and it is only my fault. But I appreciate your time and everybody else's. And I just want to size this properly. They decided not to get an engineer to do it. And now it's my job to figure this out, that's why I am seeking the knowledge from The more experienced guys in the trade.
Thanks a bunch,
Guy

 

[Seven-Delta-FortyOne]

these guys do lawn maintenance for cities, county's, and big industrial and commercial buildings. with 100's of employees, Im not looking for ways to change the way they use or power their tools Im looking for help on sizing a loadcenter and transformer, I understand everybody has their own opinion on topics like this but its not helping me by trying to explain why or what they do, I do appreciate the advise I am getting on this site.

Understood.

Just wanted clarification that you are indeed trying to design a system to charge 1,300 power tool batteries at once.

 

[wwhitney]

Im looking for help on sizing a loadcenter and transformer,

Larry pretty much nailed it in post #2; do you need more help?

Cheers, Wayne

 

[guytrinidad]

So as of right now. As seen in the photo, there are 15 chargers plugged in to the 4-PDMs
(power distribution manager) charging a total of 24 batteries at once, the 4 PDM's will not exceed 16amps total According to my flute. The spec sheet states maximum 16 amp draw for the total PD m's plugged into a 20 amp receptacle on A 20amp dedicated circuit, these 4 PDMs are daisy changed into each other. Then plugged into the 20 amp receptacle. They plan on charging Six hundred small batteries and 150 large batteries each night as of now. In the near future, they plan on having a total of 40 of these charging walls running and yes, each one charging each night so the count is 40 20 amp 120v circuits running for UP to 6 to 8 hours of charging depending on the batteries per night. Each circuit pulling a max of 16 amps And as the batteries are charged, then the PDM starts dropping off the chargers, which of course reduces the draw on each pdm. So my thoughts were to install a 80 kVA transformer with 2 possibly 325 amp loadcenters running off the one transformer, and then I could supply the 40-20 amp circuits Off of the two load centers and have room for growth as a plan on expanding.
I realize i'm throwing out a lot of information and it might be somewhat confusing.

 

[guytrinidad]

Here is another spec sheet Hopefully It is legible.

 

[wwhitney]

So my thoughts were to install a 80 kVA transformer with 2 possibly 325 amp loadcenters running off the one transformer, and then I could supply the 40-20 amp circuits Off of the two load centers and have room for growth as a plan on expanding.

Did you mean 225A load centers? As a single 225A 208Y/120V load center can support (42) 120V circuits with a load of 16A: 14 on each leg, and 14*16 = 224A.

As for transformer size, I believe standard sizes are 75 kVA and 112.5 kVA. So if you want future expansion room, or if it's actually possible for all 40 circuits to draw 16A at most, you'll need the 112.5 kVA. Otherwise, 39 * 16A * 120V = 74.88 kVA, so the 75 kVA transformer would work.

Lastly, is it actually possible for one of these 16A circuits to draw 16A continuously for more than 3 hours? Either by supplying multiple battery chargers, each of which takes over 3 hours at peak current to charge the battery (doubtful at this size battery, I would think), or because some sort of smart load manager is controlling which battery chargers are being powered to maintain a 16A draw continuously? (I didn't look at your spec sheet). If the 16A loads is continuous, they you'd need size the equipment supplying the transformer, and supplied by the transformer, with a 125% continuous load factor (e.g. the 225A load center could only 3 * 11 circuits, not 3 * 14).

Final comment: if there's a smart load manager controlling which battery chargers are getting powered, and the use case is to charge everything overnight, I would expect you could downsize the equipment quite a bit by spreading the load out over 8-12 hours. So if such a product exists, it could easily pay for itself.

Cheers, Wayne

 

[guytrinidad]

Good day, gentlemen. First of all, I want to thank everybody for their comments and the knowledge that they have applied to their messages towards my installation concern. I appreciate all of the help. So I finally decided to move forward on this job. And based on information I 've rceived I'm going to go with a 112 kVA transformer, and I am hoping to install 2-225 main breaker load centers with 40 circuits each, and I'm hoping to run them parallel off of the 112 kVA transformer. So that is my plan. I have never done that before so again, I'm asking for some knowledge on possibly running the two load centers off of the single transformer. I would appreciate any input that anybody has , thank you again.

 

[augie47]

Looks like a good plan. Recommend a 175 amp primary breaker with 4/0 secondary conductors to your 225 M/B panels.