# Allen Bradley 753 VFD



## micromind (Aug 11, 2007)

I'll be installing a 753 VFD in a couple of weeks, it's in a NEMA 12 enclosure and feeds a 250HP vertical hollowshaft motor. 

The actual wire length from the VFD terminals to the motor terminals is about 16' so even though the motor is not spike-resistant, I don't think I'll need load reactor. 

I will be using a line reactor though and if I remember from the last big 753 I installed, there's a ton of room in the cabinet above the electronics. If it'll fit, can I mount the reactor inside the cabinet? 

Again, from memory, there's no cooling inside the cabinet, will the heat from the reactor be a problem or would I be better off using a can mounted above the cabinet? 

Thanks.


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## 3DDesign (Oct 25, 2014)

Personally, I would install it in it's own enclosure. THIS PDF shows the recommended enclosure for each one. Your manufacturer may be different


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## frenchelectrican (Mar 15, 2007)

Hey Micromind.,

AB 753 VSD ?

If you got 480 volt supply I really rather ran that on it own box due the heat from reactor it can get pretty warm I dont recall how warm but just engough to get your attetion on heat rise from reactor coil.

Just make sure you have pretty decent cooling or ventation for 753 driver especially if you are going under 70% of rated speed it will get warm.


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## MDShunk (Jan 7, 2007)

The only 753's I deal with are couple hundred HP ones in Centerline MCC buckets. There's zero room for a load reactor in them, even though the bucket is full-height. We have load reactors on them all, but they're in NEMA 1 sheet metal hanging from the bar joists just above the MCC section.


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## glen1971 (Oct 10, 2012)

Indoor or outdoor install? If it is in a climate controlled room, vents in the cabinet may be sufficient. If it is outdoors, you may run into high drive temps in the summer.


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## John Valdes (May 17, 2007)

I have seen line and load reactors in the same cabinet as the drive. They were engineered panels so I did not question it.
They were quite large with AC or forced air for cooling.

Also pump motors (especially hollow shaft) are usually variable torque and will rarely run at full current if sized properly. Hence the reason you can go down a size on the VFD for this variable torque load.
There are exceptions.

Rob. Who's building the panel? If its an engineered panel, I would not concern myself.


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## JRaef (Mar 23, 2009)

As a gross general rule, there is room in a cabinet and the cooling fan is rated for a line OR a load reactor, but not both. If you add a single reactor (line or load), the enclosure size will not change. But if you try to add both it has to be engineered. They might both physically fit in the box, but the fan size may increase. it depends on what else is in there.

If you are not going to have an output reactor _*and *_the motor is not made for inverter operation, I think it's a bit risky but at least turn on Parameter 40, bit 5, which is a Reflected Wave Voltage Reduction output algorithm option to keep it at a minimum.


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## tates1882 (Sep 3, 2010)

micromind said:


> I'll be installing a 753 VFD in a couple of weeks, it's in a NEMA 12 enclosure and feeds a 250HP vertical hollowshaft motor.
> 
> The actual wire length from the VFD terminals to the motor terminals is about 16' so even though the motor is not spike-resistant, I don't think I'll need load reactor.
> 
> ...


AB has thermal management freeware that you can enter wattloss, exposed surfaces, ambient temp, paint color etc. and it will give a recommended enclosure size. Its windows based software.


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## micromind (Aug 11, 2007)

The VFD is in a factory-built enclosure. 

There is no cooling fan in the enclosure, the transistor heatsink in behind the enclosure. The only thing inside is the control boards. If I remember, there's a very small fan that blows air across the boards but no outside vents. 

It will be installed in a climate-controlled room that's pretty clean. It runs about 60º in the summer, cooler in the winter. 

I suppose I could cut a 3 or 4" muffin fan in one top corner and a vent in the opposite bottom corner. I'd lose the NEMA 12 rating but considering the environment, I doubt it'd matter.


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## frenchelectrican (Mar 15, 2007)

micromind said:


> The VFD is in a factory-built enclosure.
> 
> There is no cooling fan in the enclosure, the transistor heatsink in behind the enclosure. The only thing inside is the control boards. If I remember, there's a very small fan that blows air across the boards but no outside vents.
> 
> ...


Rob.,

The muffin fan that will work pretty well with it and you can get it somehow in 3R rating if you make a mini hood for muffin fan. But being in climate controled room that is a big plus for it.

Heatsink behind the enclosure ?? that ls little odd place but as long you have a gap in back you should be ok but some of the heatsink I am not too crazy in the back due sometime hard to clean it out.


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## tates1882 (Sep 3, 2010)

micromind said:


> The VFD is in a factory-built enclosure.
> 
> There is no cooling fan in the enclosure, the transistor heatsink in behind the enclosure. The only thing inside is the control boards. If I remember, there's a very small fan that blows air across the boards but no outside vents.
> 
> ...


If you know the details of the enclosure and vfd you could calculate the thermal load with the freeware. Then you'd know for sure if you need a fan or not if you installed the line reactor. 
Technically if you got a 4x,3r or 12 rated fan you could have an overall rating of type 5 at min which should fit your needs. You'll need to observe the min clearance from a arcing part to opening or install barriers. Is this a 12x drive or a type1 in an enclosure?


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## micromind (Aug 11, 2007)

It's a factory built NEMA 12. 

Metal enclosure with door gaskets and no ventilation. 

The freeware sounds like a good idea but I'll need to find someone who runs Windows. Should be easy though.


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## frenchelectrican (Mar 15, 2007)

micromind said:


> It's a factory built NEMA 12.
> 
> Metal enclosure with door gaskets and no ventilation.
> 
> The freeware sounds like a good idea but I'll need to find someone who runs Windows. Should be easy though.


Thanks for clear it up.,

I do have windows but I havent download that apps yet.


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## tates1882 (Sep 3, 2010)

I had it on a virtual windows machine on my MacBook but when I added a second virtual machine to run my power quality analyzer the first vm now crashes the entire MacBook. I think it was called TIA client, it had a bunch a programs inside a overall package of tools. I found it while searching for micrologix freeware years ago.


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## splatz (May 23, 2015)

There are plenty of online calculators that will figure out how much cooling you need. 

For example: 

https://coolingtool.pentairprotect.com/index.html 

I thought automationdirect had a calculator too but can't find it at the moment. 

There are also lots of reference documents out there from the makers of the enclosures and cooling products that show you how to do the calculations, it's not that hard to do if you know the wattage of all the components in the box.


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## MDShunk (Jan 7, 2007)

I have found the 753's to be very robust and tolerant of heat. Since it's an engineered panel, I wouldn't give extra ventilation a moment's thought. 

The 4's and 40's, on the other hand (what I call Allen-Bradley's disposable class drives), I find to be very intolerant of heat and require even more airflow than the manufacturer's documentation suggests.


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## Helmut (May 7, 2014)

I would of thought all engineered cabinets with VFD's and reactors would all have external cooling or external pressure fans to pressurize the cabinets, to get more HP out of the drives, and make them last longer.

I suppose that ain't the case....


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## MDShunk (Jan 7, 2007)

Helmut said:


> I would of thought all engineered cabinets with VFD's and reactors would all have external cooling or external pressure fans to pressurize the cabinets, to get more HP out of the drives, and make them last longer.
> 
> I suppose that ain't the case....


Allen Bradley does a funny thing with their drives. They give them a "normal duty" rating and a "heavy duty" rating. I size them to the "heavy duty" rating always because my past experience tells me to do that. Most also have built in fans on the drive itself. You can put fans on a NEMA 12 cabinet, but it's a god-awful looking externally baffled affair. A vortex cooler, like an Exair or a cabinet a/c pack is an option I like better if there are a good many drives in the same cabinet, such as you might have for a conveyor line control panel. Drives that are pre built in Centerline MCC buckets can have from 2-12 muffin fans factory installed.


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## Helmut (May 7, 2014)

MDShunk said:


> Allen Bradley does a funny thing with their drives. They give them a "normal duty" rating and a "heavy duty" rating. I size them to the "heavy duty" rating always because my past experience tells me to do that. Most also have built in fans on the drive itself. You can put fans on a NEMA 12 cabinet, but it's a god-awful looking externally baffled affair. A vortex cooler, like an Exair or a cabinet a/c pack is an option I like better if there are a good many drives in the same cabinet, such as you might have for a conveyor line control panel. Drives that are pre built in Centerline MCC buckets can have from 2-12 muffin fans factory installed.


Many days ago, I installed external fans on cabinets with drives in them. What a task that was. I think we used dayton blower fans from grainger. I ended up having to fabricate a cage for the input air, for a filter. All the fan did, like you say, was blow crap in the cabinet without the filter . Once the filter was done, it was just part of the weekly PM's to go blow off the filters.
It makes you stop and think about the quality of air in the place, that you're breathing all day. 

Anyway, the drives lasted longer. Remember the little KB drives? Cabinet was full of them. I don't know if they even make them still.


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## MDShunk (Jan 7, 2007)

KB remains among the most respected and most popular of DC drives. Yes, they still make them. 

My favorite, most bullet proof, AC drives remain TB Woods and Seco.


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