# Installing a 200 ton press brake...



## oldschoolvdub (Jun 10, 2007)

So I've been doing a bunch of work at a mechanic/fab shop. Recently they won a 200ton press brake at an auction and it is on it's way here. I know it requires a supply voltage of 480, and the name plate says full load current is 24 Amps. It also says largest load rating is 24 Amps. 

Now I talked to a rep at Piranha (makes the equipment) and he says that there it spikes to almost 60 amps on startup. I just want to make sure that I have the correct transformer and protection on this installation. All they have at the shop is 120/240 high leg delta. 

I also am unclear what overcurrent protection is required, and where it is required to be installed. I figure if I come out of the main panel, the breaker will be the correct protection for the transformer. Then out of the transformer (set less than 2 feet from the equipment) I will go straight into the control box. Do I need a disconnect before I hit the equipment?


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## backstay (Feb 3, 2011)

Primary only breaker 125% primary rated amps
Primary and secondary breaker 250% primary rated amps and secondary at 125%

There's more to it than just that, fuses vs breakers are not the same.

450.3(B) and Table 450.3(A) 2011 NEC

If there's a motor then you need to get into 430 also.

I guess 670 would be somewhere to look too.


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## oldschoolvdub (Jun 10, 2007)

Ok... I got into Table 450.3 (B)... Now after talking to the company again and while looking for a PDF of info, they told me that it can run up to 50 amps while it's under load sometimes. What I don't understand is why the name plate would say 24amps FLC when it's not actually that.


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## backstay (Feb 3, 2011)

oldschoolvdub said:


> Ok... I got into Table 450.3 (B)... Now after talking to the company again and while looking for a PDF of info, they told me that it can run up to 50 amps while it's under load sometimes. What I don't understand is why the name plate would say 24amps FLC when it's not actually that.


That's most likely what the motor FLA are. You can go over that for a while. They built it so it must work at that rated amps.

What size transformer is going in?


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## oldschoolvdub (Jun 10, 2007)

I was looking into an Acme transformer that is 45kva and is rated up to 56amps. If there is a spike of 60 amps I'm thinking I need to size the transformer and the wire bigger as well correct? I know the next size up is a 75kva and its good to something like 95 amps. 

This is the first design build type of thing that I have done so it's a learning experience for me. I looked up the PDF on the manufacturers website and found that they have a chart that says Short Circuit and Overload Fuse Protection. And for 460Volts they specify a type J 40 amp.


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## micromind (Aug 11, 2007)

If I were installing this, I'd see if it can be changed to 240 volts before buying a transformer. Most equipment like this can. Usually, all that's needed is to re-connect the motors (usually, the factory will run big enough wire and starters to accomodate the higher current), and change the tap on the control transformer. 

45KVA will be plenty. A 30 will almost certainly work too. 

The reason it spikes up to 60 on startup is because the locked rotor current (the surge current at startup) of the motor(s) is always higher than the full-load current. 

Any transformer can take a pretty good amount of overcurrent for motor starting. They can also take some overloading; provided it's not too long. 

The reason the press draws up to 50 amps during use is because the motor is being overloaded. This is perfectly fine, but only for a short time. Like the end of a press cycle. 

The low voltage overcurrent device can be the breaker in the 240 volt panel that feeds it. The overcurrent device on the 480 side can be the breaker or fuses in the control panel. 

If you're using a transformer that has a 480 delta connection on the 480 side, ground the B phase. If it is 277/480 wye, ground the center of the wye. 

If the 240 side of the transformer has a 120 volt tap, don't connect it to anything. Just leave it float. 

If you can give us the part number of the transformer, a bunch of us around here can help you get it connected properly. 

Rob


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## oldschoolvdub (Jun 10, 2007)

Ok cool! Pretty much everything you said is what I was thinking but I feel a lot better hearing it from someone who has done this before... 

After looking, there is no way that I can use any other voltage other than 480... I'm thinking a 30kva should work fine... its a 20 hp motor... and that's really the only thing that really draws... and there are fuses in the control panel that I can use for protection of the equipment...


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## micromind (Aug 11, 2007)

I figured it was 20HP. Think of it this way, a 30KVA transformer is larger than a 20HP motor, so if it were pushed beyond the limit, the motor would cook before the transformer. 

The slight amount of load of the controls is pretty much nothing. 

Besides, the motor has overloads that are quite a bit less than the transformer current. 

BTW, the current of a 30KVA transformer at 480 3ø is 36 amps.


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## oldschoolvdub (Jun 10, 2007)

So I just got off the phone with the manufacturer. After talking to tech who knows what hes talking about, he said I just need to go with the nameplate amperage. He said the transformer and fuses will have to be able to deal with a spike of slightly higher than 40 amps for a second or two but no more. 

I also spoke with Acme about the transformer and he said that their transformers can withstand up to 6 times its rated amperage for up to 5 or 6 seconds for the start up spike. He called out a TP1-53342-3S. It's a 30kva... 

I feel much more confidant now, but it is still kinda scary having to spec out what he needs because it's expensive and I want to make sure there will be no problems with it.


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