Warren and Redsy, I respect your opinion and affection with AB drives… I used to use nothing but AB and GE Fuji a few years ago, I’ve just developed a unique perspective on this subject over the last year, which I would like to share.
I look at drives under 100 hp as Pop (can you tell I’m from Cleveland, Ohio.) The differences between Coke, Pepsi, RC cola, and the Sam’s club stuff (generic.) I’m getting smirks now…. seriously.
I deal with troubleshooting drives everyday, I handle our brand (Hitachi) and the interfacing of everyone else’s with our controls. I’ve dealt with just about every drive in North America…. even a few odd ones in South Africa and the UK.
The technology is converging…. A Coke is similar to Pepsi in the fact that it is a Cola, it’s just different. Here is what I mean:
1. My system voltage is 500 vac; I have a highly volatile blower that has to vary speed fast and often. I wouldn’t use a Japanese drive of any make…they are historically voltage intolerant. Unless I used a bucking transformer to 460vac and used dynamic braking to filter the dc bus from regenerative trips.
2. I may use ABB’s direct torque control on a lathe that had to have decent speed control with no ability to use an encoder for vector control. If I had a greater range of variation, most sensorless vector control drives would do as well.
3. Would I buy an AB or Square D drive with a NEMA 12 case? Sure, if it was in a location where I couldn’t fit another drive (most are NEMA 1) in a NEMA 12 enclosure and save at least half the cost overall.
Problems arise from misapplication and improper set-up and installation. Most manufacturers have very low failure rates (if all procedures were followed.) There are legitimate component level failures…you will find that the figures are low when you speak to EMA, Perfection servo, or any drive repair group. Here are a few recent examples of missapp/set-up issues that I’ve ran across:
1. I want to run a vfd with an open frame motor from 1970.
2. My motor is 1000 ft away from the drive and I have existing rag wire.
3. I have 15 plugging circuits on the same distribution bus; do I need a line reactor on the power side of the drive?
I may like Coke over Pepsi, but if Coke was $3 a can versus Pepsi at $1 dollar a can, and I’m a technically savvy guy who has done my homework, then I’m buying the Pepsi.
Carl
