How does dirty power / clean power affect equipment?

Have a lot of questions but I’ll start here. The way I understand dirty power is if there is static or bad interference in electricity? Is there some sort of filter if you are receiving dirty power or would the electricity be used the same but possibly cause more wear on breakers or contactors?

Breakers dont care. Only a few pieces of special equipment do.

Just think of noise in the sine wave like you drew it with a bad shake in your arm.

Things that don't seem to like it include: servo drives, and PCs, other board-level electronics

Things that don't seem to care: single or 3 phase motors, relays, heaters.

A VFD typically outputs a very noisy sine output. The spikes can breakdown winding insulation in "old" motors, newer motors seem to be better able to handle it.

I deal with this a fair amount bacause of automation

Dirty power is noise or I think what you are calling static carried on the power line .
This can be frequency fluctuations, dips, spikes....etc

Breakers don’t care, heaters don’t care, motors don’t care much
Electronics care


Is there a filter, yes it is called a power conditioner

Items with onboard computers don't like noisy power. Microwaves, stoves, dishwashers, refrigerators now all have computer boards and don't like bad power. I have seen stoves that oven controls would be screwed up on, broil on instead of bake etc. Dishwashers with all lights on and not working etc. All that was required to fix them was to turn them off in breaker box for 2-3 minutes and then back on and everything worked right. Had one subdivision that several new houses with same dishwasher would always have the controls locked up until power reset. All these locked up at the same time from voltage spikes/noise on the main line. Finally got power company to put line monitor on grid and repaired the problem--noisy was generated by a/c compressor control problem in new school down the street. Some controls a short blip in the power would reset the control so that you had to set clock again, other controls that blip would store and confuse the control until you reset the power. The power would have to be off long enough to require a clock reset before the control would reset and reboot and work correctly. Most people don't realize that most appliance control boards are on all the time not just when operating and lights are on. Same with TV's / anything with remote control. To read a remote control the unit's board must be on, and surges will store and mess them up eventually.

Kind of along the sames lines as this topic.

I have a small 110v Mig welder (I'm not a pro by any means).
If I plug it into one outlet in my garage I get a lot of splatter and welds were not flowing smoothly.

If I keep the exact same settings but plug it into another outlet it works great.

Don't know if there is "dirty" power or too much other stuff on that same circuit.

I deal with this sporadically since my job is renting and selling generators.

This issue was a lot more common when voltage was controlled mechanically as opposed to electronically. They used to advertise voltage fluctuation at +/- 3%, nowadays its advertised at +/-.5%.

I used to run into it at hospitals. They have fancy electronics that did not like much voltage fluctuation. Their stuff would shut off frequently or flat out not work when under generator power. Renting them a line conditioner would solve the problem.

I did run into it not long ago while renting a generator to a defense contractor. They had things (not sure what you call them) that tracked the drones as the flew around. Those things were not happy with the frequency that was coming out of the generator. adding a transformer to the mix solved the problem. I'm not an engineer and I'm not the one who solved the problem so I can't tell you why that solved the problem though.

I did blow out a s**tload of light ballasts at Union Station (big train station in downtown LA) not once but twice though.......I think that was a faulty voltage regulator as opposed to "dirty" power though.

matt_i said:

Just think of noise in the sine wave like you drew it with a bad shake in your arm.

Things that don't seem to like it include: servo drives, and PCs, other board-level electronics

Things that don't seem to care: single or 3 phase motors, relays, heaters.

A VFD typically outputs a very noisy sine output. The spikes can breakdown winding insulation in "old" motors, newer motors seem to be better able to handle it.

Click to expand...

Or, DC that isn't straight line. Auto techs don't use battery chargers when working on auto computers. They use power supplies that provide pure, straight line DC, or, they get to sell a new computer. Alternators are AC devices(generators) which gets rectified to dirty DC. The battery acts as a big sump/filter to even out the spikes. That's why new(er) vehicles will not run on alternator power, so they fail catastrophically when the battery goes dead, some times while running down the road.

I suppose it all depends on how you define "dirty power".

But the general answer of "Electronics are most impacted" is correct. That and any equipment that relies on Electro Magnetic Fields (think Radios) to operate as dirty power often creates a lot of Electro Magnetic Interference.

Ok. Gotcha. Thanks folks.

So is Vars basically equal to watts?

When we are talking about power factor what exactly does this mean? Does it mean the percentage of good power? I know you want to be on lag side of 1 but if you are on the positive side of 1 then what is exactly taking place? Does this mean I’m not selling all of the power?

vrinner said:

Kind of along the sames lines as this topic.

I have a small 110v Mig welder (I'm not a pro by any means).
If I plug it into one outlet in my garage I get a lot of splatter and welds were not flowing smoothly.

If I keep the exact same settings but plug it into another outlet it works great.

Don't know if there is "dirty" power or too much other stuff on that same circuit.

Click to expand...

You have a circuit that is overtaxed already for the welder to operate on.
I have always had a dedicated plug in my garage on its own breaker and never had a problem.
Before that I had to turn off and unplug my computer when using the welder or it would kill the power supply

I've found that motors, heaters, etc... don't care much about dirty power. I've found that a lot of electronic equipment (CNC machines, stuff with servos, some electronic lights, televisions, other "smart" equipment) absolutely hates dirty power, and will have all kinds of problems.

Oddly enough, I've found that desktop computers and laptops are basically immune to dirty power. They typically have beefy power supplies with large DC bus capacitors that basically soak up everything. I've had power glitches that have caused my lights to flick completely off for half a second, and my computer kept on running like nothing happened.

vrinner said:

Kind of along the sames lines as this topic.

I have a small 110v Mig welder (I'm not a pro by any means).
If I plug it into one outlet in my garage I get a lot of splatter and welds were not flowing smoothly.

If I keep the exact same settings but plug it into another outlet it works great.

Don't know if there is "dirty" power or too much other stuff on that same circuit.

Click to expand...

rsanter said:

You have a circuit that is overtaxed already for the welder to operate on.
I have always had a dedicated plug in my garage on its own breaker and never had a problem.
Before that I had to turn off and unplug my computer when using the welder or it would kill the power supply

Click to expand...

Check the voltage. If you're plugged in on a long run, or using along extension cord, or as he^^ said, too much draw, your welder won't behave.

Zeke said:

Check the voltage. If you're plugged in on a long run, or using along extension cord, or as he^^ said, too much draw, your welder won't behave.

Click to expand...

It is at the furthest end of my house from the electrical panel and I believe the same circuit that my garage lights and lord knows what else running off that circuit. Thanks!

NOPE!
Vars and Watts are not the same.
Too much capacitor load makes PF go higher than PF1 isn't typically encountered except possibly in a huge Server Installation.
Too much Inductive load makes PF go lower than PF1. This means you have too many motors running or transformer type welders.
You want a perfect world where the PF is 1 as it means you are paying for the Amps and Volts you are actually using. Which is why people state electric heat is the most efficient.
As far as the Military Installation, in the transformer the high frequency spikes do not go across the windings which solved your problem!
There are transformers that are also built with a grounded aluminum shield between the "H" windings and the "X" windings that cancels out the high frequency if you have really bad Harmonics.

honda1998civic said:

Ok. Gotcha. Thanks folks.

So is Vars basically equal to watts?

Click to expand...

No... not exactly. VAR = Volt Ampere Reactive which is an expression about the relationship between the voltage waveform and the current/ampere waveform. So if we look at Watts vs. VAR's:



When you have a perfectly resistive load, the voltage and current waveforms are in-phase:



Resistive loads are things like incandescent lights, or a heating element, etc...

Reactive loads are either inductive or capacitive in nature. Things like motors with big windings and magnetics are inductive, whereas things like computers and other electronics can be more capacitive. Inductive loads pull current up to 90 degrees out of phase in one direction (+), and capacitive loads pull current 90 degrees out of phase with voltage in the opposite direction. (-)



A good way to remember this is: ELI the ICE man, where:

E = Electromotive Force, or Voltage
I = Current or Amperes
L = Inductive
C = Capacitive

So when E is in front of I, it's an inductive load. (Voltage leads current.) When I is in front of E, it is a capacitive load. (Voltage lags current.)

Inductive Load:



Capacitive Load:



So when we look at the loads, we will have a combination of these items typically. The inductive and capacitive loads will actually cancel each other out and it will look more like a resistive load in nature. So if we had an inductive load that was pulling the waveforms 30 degrees out of phase, and a capacitive load pulling it 10 degrees out of phase, the net result is 20 degrees out of phase.

So now that we know that we're talking about voltage and amperage, when we combine the two we have Wattage/Power. (Volts * Amps = Watts) When we have 1,000 watts, we call it 1 kilowatt, or 1kW. When we start accounting for the leading and lagging of the current waveforms, we start to see that we aren't really getting all of the power we are supposed to be getting. Here's why:

When volts and amps are in phase, they reach their highest peak at the same time. So if you have 20 volts and 10 amps, you have 200 watts.



But what happens when they are out of phase? We have to account for the phase angle between them, so when voltage is at it's peak, current isn't... so if we hit our 20 volt peak, we might only be at 7 amperes... and that's only 140 watts. As we drop down to 14 volts, we hit the peak of 10 amps... and again, that is only 140 watts.




So to express these values, we talk about Kilowatts (kW) Kilo Volt Amperes (kVA) and Kilo Volt Ampere Reactive. (kVAR) KW is 'real' power, KVA is apparent power, and KVAR is reactive power. The easiest way to understand this is a big, cold glass of beer.




kVARs are just foam... it's technically beer, but it's not worth anything. Our glass is kVA and is 'apparently' full, but the only thing we can really drink is the liquid beer.

When we are talking about power factor what exactly does this mean? Does it mean the percentage of good power? I know you want to be on lag side of 1 but if you are on the positive side of 1 then what is exactly taking place? Does this mean I’m not selling all of the power?

Click to expand...

Yes, that's pretty close. Power Factor is nothing more than a representation of the relationship between the phase angles between voltage and amperage, expressed as the kVA = kW vs. kVAR. When voltage and amperage are in-phase, Power Factor is 1. If we go either direction (inductive or capacitive) then that number is less than 1. So the more kVAR's we have (+ or -) then the more the number drops away from 1:



So if you had a +0.80 power factor, you would have a slightly inductive load. Your kW would be 80% of your kVA rating. If we use the example above, 125kVA * 0.80 = 100kW. If the number were negative, it would be a capacitive load.

Hope this helps.

Mark

Great explanation Mark. You've got a better handle on this than most ticketed electricians! Are you an engineer or perhaps an electrician who does a fair bit of commercial or industrial work?

matt_i said:

Things that don't seem to like it include: servo drives, and PCs, other board-level electronics

Click to expand...

On almost all of those items, the AC is converted to DC, with th most common method being switching power supply. All modern DC power supplies can take a wide range of voltages. Some can even accept 120V@60Hz or 240V@50V without having to flip a switch.

If you look at a "block diagram" of a switching power supply, the first thing that happens is the AC is rectified to DC. Then it is filter (somewhat) to take out sags and spikes. It is still not a "perfect" DC voltage. As long as that filtered DC voltage is high enough for the second stage, there is no issue.

Motors don't care much about small and short sags or spikes because rotational momentum will let it "ride" through.

rsanter said:

Breakers don’t care, heaters don’t care, motors don’t care much
Electronics care

Click to expand...

If you are seeing "noise" on your low voltage DC circuits, that noise is being "induced" from high voltage electric power.

Milton Shaw said:

Items with onboard computers don't like noisy power.

Click to expand...

But how much noise is too much ?

In a previous life I designed electronic fuel injection systems. You can put a lab 'scope probe on any trace in a onboard EFI system and see inductive "kick back" from every injector or ignition coil firing ! I might be less than 10mV, but it is there.

I still got problems with a 3 way.

conductors, resistors, capacitors, fuses and such can get fubared

sberry said:

I still got problems with a 3 way.

Click to expand...

Yep, women be crazy enough -- let alone dealing with 2