Investor Drive

[Smart Sparks]

Hi there,
I am a newby to the forum and was wondering if anyone could tell me how invertor drives actually work?.

 

[Knobhead]

Have a look on Google there's far more stuff there than could be put in a few posts here.

 

[silva.foxx]

Hi there,
I am a newby to the forum and was wondering if anyone could tell me how invertor drives actually work?.

Pardon me...but I have to assume you have Googled it and had zero hits...

other than that, read this...

View attachment Facts Worth Knowing.pdf

 

[snowhead]

In simplest terms;

The AC input to the drive is converted to D.C.

The drive uses the D.C to produce what looks like an A.C supply to the motor, but which is actually a pulsed D.C supply (mimicking a Sine Wave).

The advantage of using a D.C supply is you can then more easily alter and control the output.

Inverter drives (VSD) can control the initial start speed and increase in speed, the running speed as well as the rate of slowing down.
All this and be able to monitor and alert or alarm and cut the supply to the motor if it starts to run outside of its safe working parameters.

I love VSD's, I used to just press the overload to restart the motor.
Now I have to find the manual, check the fault parameter displayed, clear the fault, check the fault history, correct any settings that might be out of range then wait for the next minor power disrturbance and repeat.

.

 

[mechelec]

An investor drive is what banks do to get people to put money in savings.

 

[Knobhead]

I love VSD's, I used to just press the overload to restart the motor.
Now I have to find the manual, check the fault parameter displayed, clear the fault, check the fault history, correct any settings that might be out of range then wait for the next minor power disrturbance and repeat.

Don’t you just love the way they’ll find more ways to shut down than behave and run?

One of the last I fitted was to drive a set of rollers rotating a pipe. OK seemed a good idea at the time…. The pipes weighted 5.5 tonnes and could be oval in shape.
So first excuse to trip, overload trying to get the pipe up hill.
Second excuse, over speed as the pipe ran away down hill.
It wasn’t long before it was back on a DOL and O/L’s.

Told them it wouldn’t work but it was a “management” decision so had to be right!

 

[telectrix]

.don't you just love it when the suited know=alls are proven wrong.

 

[mikehopkins]

.don't you just love it when the suited know=alls are proven wrong.

yes yes

 

[snowhead]

I don't install, only replace when they fail.
But have suffered them being fitted on almost EVERY motor on every site I visit.

All in the interests of energy saving.
They get a bit carried away sometimes when we have to get AHU's running again, which are not required, just so the Energy Saving teams can fit VSD to save energy.

Wake up, they were switched off saving 100%, now they are back on with VSD control "saving " energy.

 

[Wazzajnr]

To be fair, a correctly sized and installed drive should almost never trip. let's not blame the drive but the engineer who has "guessed" the size of drive.
With regard to finding the fault when they do trip, i normally do a common trip code list for panels that i visit regularly. That said, most of the drives i work with are from one of 4 manufacturers so i'm quite clued up on the trip codes.

 

[snowhead]

Some of the ones I see have no guesswork, 22kw motor = 22kw drive.
They're the ones we have most trouble with, when they are on the limit.

 

[Wazzajnr]

Exactly, They would need to be a 22kw HD (Heavy duty) Rated inverter so that they can supply overcurrent for a specified time to cope with imbalanced loads etc.

 

[Smart Sparks]

Thanks for the detailed reply, It makes a lot more sense to me now.......appreciate your help.