Insane Instruction Manual?

You need a serious controller if you are running 34,000HP! (From Allen-Bradley site)

Drives

PowerFlex® 70 AC Drives

When you need a fully-featured, outstanding performance drive that connects seamlessly into your integrated architecture, you can count on PowerFlex Architecture Class AC drives, which offer an extensive range of power ratings 0.37 kW - 25.4 mW (0.5 Hp - 34000 Hp) and motor control technologies while offering seamless architecture connectivity.

It sounds like sales splurge. Ignore it.

Set the overcurrent protection device in the drive to the full load current of the motor downstream of it, and all the flowers in the garden will be lovely.

Yes, 120 megawatts is just crazy talk. The real max value is much less, a mere 25 megawatts.

Drives

PowerFlex® 70 AC Drives

When you need a fully-featured, outstanding performance drive that connects seamlessly into your integrated architecture, you can count on PowerFlex Architecture Class AC drives, which offer an extensive range of power ratings 0.37 kW - 25.4 mW (0.5 Hp - 34000 Hp) and motor control technologies while offering seamless architecture connectivity.

(From the website)

I think that may have something to do with the source impedance. Either that, or it's a misprint.

Having had some time to think about it, I believe Bill is right. At this point I think it is saying something about the mass of the power transformer core from which power is taken. I'm still trying to translate from "Geek" to English. I have detected other statements in this manual and in many of the other AB manuals written in pure "Geek". I suppose that is necessary in certain places, but it makes me think a lawyer was involved in creating the manual. As a lot of people point out, I will probably just ignore it unless there are problems.

One of the problems with manuals is that they are full of a lot of mundane stuff that has to be there for the uninitiated. The problem is that I sometimes have a hard time telling when the dialect has switched from ordinary English into "Geek". Once I have detected it, all I have to do is switch on my "Geek language" translator and suddenly I am enlightened!

GA, Paulus. I think you nailed it.

Paul is exactly correct. The unit is to be used with supply not capable of more than 200,000 A. This is the interrupting capacity of the supply. Attached to a 30 Amp 600v mains (small plant) no problem attach this unit to the main bus of a say Car Assembly Plant (upwards of 6000 A supply) and you may have a problem if the supply will not reliably interrupt. IC (Interrupting Capacity) ratings are more and more required on equipment. 100,000 A IC fuses, disconnects etc. and sometimes special calculations are required.

Maybe its just a reference to say that the drive has an integrated reactor to enure peak charging currents are OK on any supply to this capacity.

This means low source impedance or 'normal' supplies.

I suspect the smaller drives are fuseless, they normally are, and the IM specifies relevant fusing / circuit protection accordingly.

Historically, some VFD may specify that on certain supplies they recommend the use of reactors (presumably to protect diodes etc in the inrush circuit etc).

Some lower cost drives have minimum (or no) inrush crcuit relying on mains impedance and so would be vulnerable to a very strong supply by peak charging currents at starting and in operation.

The 600V relates to your drive selection, in this case choosing the 575V series, as obviously, 600V would cause the 200V and 400v series some problems! (Kaboooom!!!), again just stating they can handle supplies up to 600V.

The reason that the manual is badly written and difficult to understand is because its written by an engineer who is trying to prove how clever he is!

This happens lots of times and just proves that manuals need to be checked by someone who will be using the equipment.

Then they will be written in a way that makes sense!

Key words here are :

"UP TO A MAXIMUM of 200,000 rms symmetrical amperes, and a MAXIMUM of 600 volts."

Anything below those values is acceptable.Obviously, they are speaking of PowerFlex Drives in general, not a specific model of drive.

Obviously, your 2 hp motor is below these maximum values.You should be ok.

Now as far as fuses are concerned, they are rated a specified amperage, but also at a particular AIC(ampere interupting capacity), which must be sufficient to handle the short circuit current available from the supply feeding the load that is fused.

Hope this helps

HTRN

As others have pointed out, this is just a "weasel word" statement to protect themselves against someone doing something stupid, such as connecting this VFD to the output of a 500MVA transformer. The VFD will have been UL listed and given an "SCCR" (Short Circuit Current Rating) based on being protected by fuses, the manual will tell you the exact fuse sizes for each different size of drive. These fuses that they UL listed with have a maximum interrupt of 200kAIC, so all they are saying is that you cannot hook it up to anything that the fuses cannot safely interrupt. Don't read more into it that it says.

And the REASON it has to say things like this is, someone at some time probably did hook one up to a big ass transformer and the fuses blew but failed to interrupt the current, so someone got sued. That's how all of these manuals end up with this kind of crap. I know, I used to write manuals (for VFDs in particular).

NotUrOrdinaryJoe,

The electrical codes are based on a lot of experience; not just theory. When you short-circuit a source of input power, it can momentarily deliver a much higher current than its normal output rating. This current is generally limited by the source's internal impedance and its kVA size. There are many engineering fine points beyond this that show the delivered current to be lower, but they don't matter in this answer. Your equipment is designed to be able to safely handle a short circuit of the size given without blowing up and causing physical damage to adjacent equipment or people. If the available fault current is higher than the value given, then it is possible for a short-circuit in your equipment to cause significant damage or harm outside of its own enclosure. If the designs are tested by independent third-party laboratories or agencies, then the equipment will bear a label certifying its meeting these testing standards and the laboratory doing the work. Therefore, what you have been reading is a statement of safety, important to the engineer or designer doing your work. A rating of safety up to 200kA is pretty large, and (as others have noted) of concern only in or alongside some very large utility transformers.

--JMM