I was talking with a tech last week, and he was telling me that while he was working on a drive, a fault at the motor caused a fireball to shoot out of the vfd and pass right by his head.
hmy:
I have heard versions of this kind of story over and over again, they are generally myths or exaggerations fostered by the fact that most people do not understand what a VFD is, so they attribute all sort of magical thinking to them, including mysterious "fireballs" and such. Much more likely versions:
1) He witnessed an Arc Flash event having nothing whatsoever to do with it being a VFD, but because there
was a VFD in the box, it was automatically to blame in his mind.
2) Someone dropped a tool across the DC bus connections and the tool vaporized, causing the arc flash event to be
in the drive. I had a 25 year veteran drive technician killed by that once, very tragic.
3) He energized a VFD in sub-zero temperatures and the capacitors were frozen, which can sometimes cause them to rupture somewhat catastrophically. I have witnessed some very violent versions of this, it can scare the bejeebus out of someone who doesn't know what's happening. But there is no "fireball", just a loud popping sound and occasionally some goo coming out of the caps.
Back to the motor sizing: Motor HP is a relatively meaningless term in the chiller industry. Chiller mfrs rarely list a HP value, because the motor is custom made for the chiller and it is not a COTS motor. So the chiller mfr specifies a speed and torque requirement tailored to operate their chiller design, the motor mfrs respond to exactly what they need and the nameplate for the motor is created
after testing on the chiller to provide the necessary relevant information. That's why you don't see the term "FLA" on the nameplate, there is no operation at anything less than what it was designed for, or more than what it is designed for. So what you see is the RLA, LRA and MCA or MOCP.
Usually the only time you need a HP value is when you are using something like SKM software to calculate Arc Flash energy contributions, and in that software you apparently have to chose HP or KW for the entire study, you cannot mix them. If all of the other motors are HP and the chiller is only shown with kW, just use the formula to convert and plug the nearest HP value into the software, the tiny differences will have no real effect on the outcome. And if there is a VFD, it's a moot point anyway.