Keeping VFD inverters powered up?

[bletchmonster]

Good morning.
I have recently gone down the vfd phase converter route big time to do away with my animal rotary phase converter.
I've changed 5 machines to vfd so far.
My question is what is the forum opinion on leaving vfd inverters powered up when not in use? obviously there's a small electricity use that has the benefit of keeping them warm and dry, but they are all in enclosures!
What I'm asking, is it detrimental for the capacitors etc to be constantly energised?
Cheers, Ed

 

[timgunn1962]

Leaving them powered doesn't cause any problems. At work, we have duty/standby machines where both VFDs are always powered, but only one runs at a time. Typically, they'll get changed over at 3-month intervals and we've had the VFDs (15 kW Telemecanique Altivar 31s) on since 2006 (when they replaced the previous Siemens MidiMasters, which had failed after about 7 years).
VFDs don't like not being powered for (very) long periods, as the capacitors break down, so make sure you power up at least annually.

 

[dave h 2]

???
I understood that machines powered from VFD should be switched before the VFD and then controlled from the pendant only. In other words the VFD is only powered when the machine is running.

 

[Agroshield]

I understood that machines powered from VFD should be switched before the VFD and then controlled from the pendant only. In other words the VFD is only powered when the machine is running.

If we replaced "VFD" in the original question with "TV", it is asking if it is OK to leave the TV on standby when not in use or if it should be switched off and unplugged at the wall.

In principle, standby uses more electricity than is strictly necessary, but the slight warmth from having it powered up will drive off any damp so could be a benefit in a workshop.

It is bad form to switch the mains-side input to the VFD when the output is active (high). So any switch before the VFD should only be used when its output is low. The pendant controls only the output side (same as a TV remote).

 

[Seadog]

???
I understood that machines powered from VFD should be switched before the VFD and then controlled from the pendant only. In other words the VFD is only powered when the machine is running.

The VFD has to be powered to run the machine, but then the machine doesn't have to be running until it's signalled to.

 

[bletchmonster]

That was what I asking really. Is it good or bad to leave vfd's in what is effectively standby mode.
Do should I knock them all off when I go home at night?

 

[minimutly]

If a little background usage doesn't bother you leave them on, they will love you for it.
Personally I switch mine off (when I remember).

 

[daleyd]

I turn mine off as there may be days/weeks between using them. If I’m in and out of the workshop through the day they stay on.

They shouldn’t use much electricity as just the electronics will be powered but every little helps I guess. In work as said above, some are powered for long periods before being run. But I’m not sure there’s much benefit if your not going to be using them for a long time.

 

[Anguz]

We have loads of vsd's at work.. from fractions of kW to several 100's of kw.
They do occasionally fail on switch on, don't seem to fail if just left on.
It's quite a thump from the mains if the dc bus has discharged

 

[timgunn1962]

A VFD has an input stage that takes the AC input, rectifies it to DC and smooths/stores it in a capacitor bank (aka the "DC bus"). This part is operating as long as the power is on

The control electronics are powered from the DC bus and will drive the output when the appropriate signals are present.

It doesn't take much power at all to maintain the DC bus and to power the control electronics while the drive is idle, but there are 8760 hours in a year, so it can add up. Even 5 Watts is around 44 kWhr/yr: around 12 quid at the recently-announced electricity price cap of 27.03p/kWhr.

 

[RichardM]

The only thing I would check - Is the place insured and if so what does your insurance policy say about unattended equipment.

 

[skotl]

The only thing I would check - Is the place insured and if so what does your insurance policy say about unattended equipment.

Not sure if a VFD would count as "unattended equipment" It is (almost) the same as a USB charger or doorbell transformer.

A running lathe or CNC machine - definitely unattended equipment, but VFDs, clocks, plugged-in-but-not-running microwaves & kettles, DAB radios etc. I'm not so sure.

 

[bletchmonster]

Thank you for the replies fellas.
It's
looking like I'll leave them powered up for the day after the first startup and just isolate them if it's looking like no further use for a lengthy period.
I've put a monster 15kw 220 to 380v on my radial arm drill. It's only a 5hp motor but a heavy start when using the pillar rise and fall.
The initial power up will trip the 32amp mcb, but reset the mcb and it's fine. Once that initial inrush is overcome the thing doesn't give the slightest flicker to the lights even on the heaviest starts. Incredible box of tricks!
I might try and ascertain what it's standby lecky consumption is and consider leaving it on.