# OK To Leave The VFD Powered UP?



## Janderso (May 9, 2018)

Hi,
The only way I can power down my VFD for the Bridgeport is to turn off the breaker. Is it OK to leave powered up?
I have the lathe, the TIG and the BP all on the same 220 circuit. (I would never use more than one at a time).
Should I install a power/stop switch?
Thanks.
Jeff


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## Crank (May 9, 2018)

Jeff,
My TECO FM50 just like yours has been on since I wired the circuit 8 years ago. Still working fine. The principle is that electronics don't like heat cycling, that's why I never turn off my home computer either.

Mark


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## JimDawson (May 9, 2018)

Mine are powered up continuously.  Keeps them warm & dry.  No thermal cycling that way.


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## dlane (May 9, 2018)

I put a disconnect before my vfd and shut it down , but have heard leaving them on is ok , I don’t like the blinking LEDs
Also don’t want it to overheat, the shop gets hot


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## Janderso (May 9, 2018)

I will leave it on with confidence. Thanks!


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## Ray C (May 9, 2018)

If it has a cooling fan, that will go bad but, they are not difficult to replace.  Those small fans have a typical lifetime of 4-5 years, provided you keep them fairly clean.   The electrical components won't mind at all provided temperatures are maintained somewhere the middle range of the allowed values.

Ray


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## Cadillac (May 9, 2018)

Just my 2cents but I would think recommending to leave any piece of machinery ON unattended is the worst advice that can be given. First your powering electrical that consumes power that your wasting. Second and most importantly is safety. You should have access to complete shutdown within steps. What if you accidentally hit run while walking past with a flycutter installed and close to chuck or something sitting on chuck and shoots it. Or a child hits the green button and wham. lathe even worse with apron controls.
All for not adding a five dollar on /off switch


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## JimDawson (May 10, 2018)

Cadillac said:


> Just my 2cents but I would think recommending to leave any piece of machinery ON unattended is the worst advice that can be given. First your powering electrical that consumes power that your wasting.



I can't argue with that.  My shop has a continuous base load of about 240 watts, VFDs, battery chargers, computers, ect.   But given that my monthly power usage averages about 2.5 megawatt hours, the shop base load is pretty much in the noise.



> Second and most importantly is safety. You should have access to complete shutdown within steps. What if you accidentally hit run while walking past with a flycutter installed and close to chuck or something sitting on chuck and shoots it. Or a child hits the green button and wham. lathe even worse with apron controls.
> All for not adding a five dollar on /off switch



Can't argue with safety either.  That is what latching stop buttons are for.  They require that you twist and pull out before the green button is active.  On my mill, a child would require a step ladder to get to the spindle controls, then twist and pull out the stop button before pressing the green button.  On the lathe, it's a 3 step process to turn on the spindle.  Twist and pull out the stop button, press the green control power button, then shift the apron control lever.  Pretty hard to accidentally start either machine.

In addition no children are allowed in my shop without direct adult supervision.  If I did have children around all the time, the machines would have key locks, and the shop would be locked also.


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## Cadillac (May 10, 2018)

Wasting power isn't  a biggie. But the display is lite so that has a hour life. Who knows how the capacitors and what not are. To me electronics are kind of temperamental. I would rather shut it down and “save” the life of them.
Who know what could happen with a surge or something.
Most machine have a 2step process to start. Theirs a reason for that. Now I’m not a safety nazi but working around these machines is dangerous enough. When I wired my machines I thought about what it would be like if I sold it. And I wanted to challenge myself to duplicate what was “the right way” to wire control circuits and such. To each his own I just don’t like people getting hurt from stupidity.


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## Crank (May 10, 2018)

Okay, I'm going to pipe up on one thing. Stop and ask yourself one question!

"Do I have a disconnect switch on every powered device that has current applied when not in operation, but is running electronics for low level function ?"

This question applies to devices that lack a mechanical switch (vs. a relay), such as: microwave, alarm clock, television, refrigerator, washer/dryer, CPAP, cordless phone, garage door opener, thermostat, etc...

Barring those industrial level items that use 440V, all of the above work with 120-220VAC. Which will start a fire with just as much vigor as anything, in addition to being able to kill you dead if you mess with it in ways you shouldn't.

Stop and breathe, we live in a world where we are surrounded by electrons in a holding pattern waiting to do our bidding (Thank you Nikola Tesla!). Just because it is attached to a big hunk of iron does not inherently pose a greater risk than we unknowingly subject ourselves to in our homes. I fully agree that a master switch to kill main power to a given area is a wise thing, but the fact that a device has power present when in the OFF position is not grounds for fear.

Rant concluded...

now back to our normal HM programming.
Thanks

Mark


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## tcarrington (May 10, 2018)

I have installed, maintained, but seldom replaced VFDs. Most of the ones I have designed and installed are on large welding equipment 120-240-480 volts, 1 to 50 HP. They occupy shops that are frequently open to the outdoors. The shops are welding shops with all the grit and airborne debris you can imagine. I have been in those shops when it was 105 outside and below freezing with the doors open. The VFDs are all happy. Some customers leave them on all the time, some turn them off. Yet, the VFDs are all happy and vary the frequency and voltage just like new.


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## Cadillac (May 10, 2018)

Crank all your appliances are stationary devices. Yeah you can get electrocuted but hey what's the other option? That's why theirs codes that your builder followed so your house should be "safe". When people run extension cords as runs,or have stacks of cords plugged into a splitter overloading the circuit they're asking for their house to burn. 
 Your appliances and electrical goods are all ran through test and put to a UL standard at least American goods so they don't harm the user. Look for example when the lithium batteries were blowin up in the samsungs. They fixed. 
 Rotating machinery is a little different we can both agree right. Like said to each his own and I'm not a safety guy but if I can wire a simple on off switch to keep from accidents happening from a machine I'm not even wanting ON then I'm gonna. I just don't understand why one would leave any machine "ON" when they're not in the room expectially when it can harm someone just by turning it ON. 
 TCAR a friend and I were just having a conversation about if you can run welders of a vfd. I didn't have a answer for him other than if you have it set to 60 hz it looks like it would work. Guessing that you would have to spec the vfd amps to welder maximum amperage pull??? That's sounds pricey!


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## Crank (May 10, 2018)

Cadillac, 
Please understand that I am not trying to be argumentative. Unless your idea of rotating machinery means it spins around the room, they are stationary also.
You missed my point. I don't mean powered and operating systems, merely any device which has electric power available and is switched off. I was referring to devices that draw power to maintain memory or actuate a relay for when it is called upon to operate. Nothing more than that. 

The original question was would the unit be harmed by having power available to the unit. A number of us agreed it would be fine. Safety is the decision of the end user. I personally feel the risk is negligible with the power off. YMMV

Mark


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## Dave Paine (May 10, 2018)

I posted yesterday, but it seems the new server lost my post.

It seems I am the only person on the forum who does not have a reliable power supply, as in any day I can have a blip, more than one some days.   I am on the edge of the utility company supply.  These blips can and do create voltage spikes, similar to flipping a switch off, then on.   A friend had his young child do this on a power strip.   It broke his external storage device.

I disconnect my DRO's and any equipment with sensitive electronics which can potentially be damaged by power blips and voltage spikes.   For my computers and home stereo, I have UPS.


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## Crank (May 10, 2018)

Dave, 
Your point is very valid and would be an excellent reason to incorporate master switches.

Mark


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## JimDawson (May 10, 2018)

Dave Paine said:


> I posted yesterday, but it seems the new server lost my post.
> 
> It seems I am the only person on the forum who does not have a reliable power supply, as in any day I can have a blip, more than one some days.   I am on the edge of the utility company supply.  These blips can and do create voltage spikes, similar to flipping a switch off, then on.   A friend had his young child do this on a power strip.   It broke his external storage device.
> 
> I disconnect my DRO's and any equipment with sensitive electronics which can potentially be damaged by power blips and voltage spikes.   For my computers and home stereo, I have UPS.



I have the same problem, happens all the time around here.  Last month my high voltage was 370.24, don't know how long that lasted, but no equipment damaged.  High voltage this month so far is 247.30


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## d4xycrq (May 13, 2018)

If you have a Ham Radio operator for a neighbour, he'd very much appreciate if you turned that puppy off.  My VFD gives me "S9+10" on my HF rigs.  Any my broadcast AM radios as well.  QRM!


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## mksj (May 13, 2018)

Many machines and appliances use VFDs/motor controllers and they are left on/running 24/7. The baseline VFD energy draw is low (around 20-25W for a 2-3 Hp unit) and as long as the fan is programmed to turn on only when driving a motor or based on heat sink temperature, they are designed to run 15-25 years (MTBF). Actually one of the biggest failure modes of a VFD is lack of use (storage) causing capacitor failure.  If a VFD has not been powered up in 1+ years then there is a specific protocol to powering up the VFD. VFDs can also fail because of rapidly cycling them on/off more frequently at intervals under 5 minutes due to capacitor inrush (although most VFDs do address this by temporarily using some form of resistive  device). So from a general argument, a VFD is designed based on continuous operational use (staying on) for years. VFDs do have timers for component life, so the capacitors usually have an 8,000 hour rating. What is not clear if this is based on powered on or operational use, if the latter than the capacitors would be rated for 320 days. More expensive VFDs have modular construction so portions/individual components can be replaced.

Many newer motor controls for things like pool pumps, AC units, etc. that use VFD's or BLDC drives are designed to operate for extended 24/7 periods under some pretty harsh conditions for years/decades. Although the drive is the most common component to fail, and this is typically due to voltage spikes and ambient heat. RFI problems should only be an issue when the VFD is running a motor, statically there is no PWM output generated. The power supply is just a DC bus, but no pulse switching is occurring.  Heat generated/dissipated would be nominal in the static powered up state, this  may be advantageous if your shop is subject to freezing conditions in the winter. In the summer, heat kills components, in particular capacitors.

So what is the downside of leaving the VFD on 24/7, mostly safety and also line voltage fluctuations causing component failure. Line voltage fluctuations and spikes is becoming a significant problem these days, and often you will see failures of electrical equipment due to this. If you have a lightening strike nearby, or when the power comes back on you can see some pretty wild voltage spikes. This kills electronic components.  Electrical equipment often have some form of input surge protection, but these are usually MOVs which have a finite lifespan and cannot dissipate large voltage spikes. I use an industrial line surge suppressor at my service entrance, one at each sub-panel and RFI/EMI filters with surge protection going to my VFDs or at the sub panel feeding them. On a safety stand point of view, I like to disconnect the power when I am done using my equipment/tools.

It really comes down to your work environment and use of your equipment/machines, if you are using it daily then I see no reason/need to turn off a VFD based on a longevity use. Akin to if you leave your computer on 24/7 (going into sleep mode)  or turn it off at the end of the day.  If you use it less frequently then daily then I would turn off the VFD. Since I only use my VFD machines every couple of days, I turn mine off at the end of the day.  If there is any chance of kids or another person getting their hands on the machine controls (no matter how remote) then I would turn them off and push the E-Stop. I build a lot of redundancy in my control systems, because as remote a chance of something happening, it is not "0" and I would rather be safe than sorry. Another reason why I turn my machines off when not using them., and disconnect the power completely if I am servicing them.


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## Cadillac STS (May 13, 2018)

Crank said:


> Okay, I'm going to pipe up on one thing. Stop and ask yourself one question!
> 
> "Do I have a disconnect switch on every powered device that has current applied when not in operation, but is running electronics for low level function ?"
> 
> ...



One exception being the coffee maker. People always want to unplug that, other things can be kept plugged in.


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## Janderso (May 20, 2018)

Interesting, many of you brought up your inconsistent power supply. You all live in the United States near or in big cities.
Many view points, I am leaning to install a simple on-off switch. It has to be better than flipping the breaker every time I need/want to use my lathe or mill.
Thank you for the advice as always.


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