Allen-Bradley 480VAC Motor Drives Conking Out

GA from me. I have nothing to add.

regards,

Vulcan

Well it's not exactly an AB ploy.

has to do with making the drives smaller & lighter. smaller heat sinks & caps. this leaves them more susceptible to damage from abuse.

Switchmans comments are very true. even on simple on/off applications, program in a little ramp up/down time if possible. Brown outs from neighboring loads

avoiding powering up & down: contactor controlling inverter is a bad plan

long runs of the output wiring=bad, the control is not as critical, mount a can as close to the motor as possible.

inverter duty motors=good

oversized drives=good, a 2 hp running a 1 hp motor, will fault out & keep running until the motor is totally fried.

Thanks everyone for replying with your helpful info . Although some of the stuff you talk about is a little over my head , you have given me some good ideas on how to rectify this problem . One question , how do the line reactors actually work ? I noticed in a different part of the building a drive cabinet is loaded with them . Always knew they were there , just didn't know exactly how they worked . Thanks again everyone for taking the time .

Tim

Reactors add impeadance to the AC line. Impeadance is used to reduce the rate of change of current.

Simply put- It filters the AC line; or if used on output of drive it will filter the current waveform 'seen' by the motor, and reduce harmonics that tend to be wasted power.

Adding impeadance is sometimes refered to as 'softening' the line. A stiff AC line will produce spikes for every disturbance on the line. (ie. switching loads)

Imagine a car without shock absorbers- It runs fine on a smooth road at any speed. Add bumps to the road, and you must slow down to keep control, or add shocks to absorb the bumps. A stiff AC line gets 'upset' for every bump, and these spikes 'wear out' the drive input filtering.

There is a whole science on AC line analysis-and it is very complicated, and very unecessary for most industrial troubleshooting concerns. However matching the drive to the ac supply is important-- Typically drives have a spec for max input supply KVA.

Also a big concern is large ratio step down transformers-- For instance a drive will work fine on a 460 to 240V xfmr; but the same drive will not work on a 2300 to 240V xfmr without adding additional filtering (swamping networks)

Hope this helps

Much more simply

motors are inductive loads

Capacitors are used to balance the load

if the load is inductive the voltage wave leads the current waveform

if the load is capacitive the current leads the voltage wave form

A simple way to remember is ELI E=voltage, L=inductor, I=current

ICE I=current, C=capacitive, E=Voltage

The more balanced the load the more efficent the transfer of energy.

if the balance is really off you will let all the smoke out of the drive or windings.

you would then need to contact KrisDel for replacement smoke [tongue firmly in cheek]

He was asking about reactors- Not capacitors.

Line reactors are not used for load balancing. I do agree with what you say regarding load balancing capacitors and power factor, but disagree with the "Much more simply" statement.

Er Uhh

Yeah actually reading woud be good......

I shall post a silly picture now to mask my embarassment

Mevel , thank you for the explaination on reactors , very well put and easy to understand . Garth , no need to be embarrased , even a "wrong" answer here is helpful in my gaining electrical knowledge . .....And the smoke comment , that's funny . Gonna have to remember that one !!! Thanks again .

Tim

Well no actual embarrassment

just my way of apologizing to mevel

another way to break the tension in those high stress moments of a breakdown during production or start-up, especially if something real expensive just quit. walk up to the boss with your best poker face & say

"there was an incident"

keeping your wits about you when the whole place is falling apart is a very important skill. Act like you know what you're doing, even when you don't have a clue. Production & mgt. need to be reassured, you're on it. Real hard to figure out the problem when there's 5 bosses looking over your shoulder & everyone's convinced the sky is falling.

AB touchscreens & PLC's are the conspiracy. Todays touchscreen won't work on a 5 year old system unless you have current software which can be a bit pricey and may require programer to fix the conflicts....

Sorry about being a bit behind the curve on this one but I finally found where I had stuck this link from Allen Bradley about reactors. Might not directly help but it's decent info.

http://www.ab.com/support/abdrives/documentation/techpapers/Line%20Reactors%20and%20AC%20Drives1.pdf

The same problem happened in my shop. The factory rep said to remove the internal board ground clip. this seems to have solved our problem. (This is on the left side of the drive) I have 10 of these drives in and around my plant. An input line reactor is a must for these drives.