I have heard of buy haven't payed to much attention to is that apparently if you want to get a 240V 50Hz chokes in the US you can use 277V 60Hz. Is this really possible? From what I have heard is that the extra voltage of 277 is enough to counter the 60Hz giving the coil less reactance than designed. What I really want to know however is that, are you able to do the same thing over here? Would it be possible that I could import a ballast from the US an use it here. I know I can use power converters but I'd like to find a drop in arrangement. Would it be possible if I put a full 180 on the method I said before, use 277V 60Hz ballast on 240V 50Hz? I will build myself a converter to do it properly and also an excuse to make something that is actually somewhat useful. I'm not expecting that it will work at all but if I don't ask I'll never know. Cheers guys!

I believe you can use the 277V tapping if there is one, but what we did is get a US 12V inverter which gives us 120V at 60Hz. It runs off a 40A 12V supply I already had for my amateur radio gear.

Info if you're interested:

Inverter

Power supply

Using 230V 50Hz ballasts at 277V 60Hz works with choke ballasts. For the higher voltage, the ballast must provide higher impedance to keep the same lamp current. The higher impedance, which happens to be spot on to what is actually needed, is achieved at the higher frequency

The requirement can be written as :

Voltage / Frequency = (approximately) constant

230V / 50Hz = 4.6
277V / 60Hz = 4.616

There is an underlying assumption here, that the voltage drop on the choke (which is vector difference of the line voltage, lamp arc voltage, and voltage drop on the ballast wire resistance) is on the same order as the full line voltage. This is a fair enough assumption for a wide range of FL chokes, probably coverying most lamps from F4T5 (where the choke voltage drop is nearly the full 230V) up to the higher power PL-C's and 58W T8 or so (where it is in the 200V area)

For a choke ballast the reverse (using 277V ballast at 230V) would also work, with one catch : If there is some tube with extremely high arc voltage (think 6ft+ tube), it might really need the 277Voc - It might not start or have hard starts at 240V, regardless of frequency



Low power factor lag autotransformer ballasts can be viewed to some extent as a combination of choke + step up transformer :

The choke behaves the same as a stand alone choke

The transformer conversion factor works normally (so the Voc will be proportional to the voltage). Using 230V ballast at 277V would not be a problem, but using 277V ballast at 230V could have unsufficient Voc for long tubes

The transformer magnetization also works like a choke, here - a choke connected directly across the line. We dont normally care about it since it doesn't matter to the tube, but in this case, we dont want it to saturate. The requirement is the same as for a choke, V/F (new) should not be higher than V/F (old). (The ballast design does account for high line voltage etc, so you dont have to satisfy this precisely, but just "not significantly higher"). With 220..240V 50 Hz vs 277V 60Hz this is satisfied



High power factor ballasts contain capacitors, which frequency response is opposite to that of chokes. And there we have a problem : The effects of the voltage and frequency dont compensate, but add up

Using 230V 50Hz ballast at 277V 60Hz will cause overcurrent : The current is higher first due to the voltage, and then some more due to the frequency

Using 277V 60Hz ballast at 230V 50Hz will cause undercurrent

Resonant circuit's behavior can be way off what's intended, depending on where the resonance frequency is vs. frequency applied

For example :

In lamp circuits with leading power factor, the capacitor impedance is dominant, i.e. it is higher than that of the choke. If the frequency goes up, the capacitor impedance goes down and choke impedance goes up. (As the overall impedance is subtraction of the two, it means that it goes down, double as fast). Resonance is defined as the frequency where the impedances cancel out completely

It is normally higher than either 50 or 60 Hz so e.g. an SRS ballast for 50Hz won't be quite at resonance at 60Hz, but the effect of the different frequency getting closer to the resonance point could have sufficient effect to make things work way off spec and could damage the lamps or the ballast



Some lag ballasts might have built in EMI suppression capacitors or Voc division capacitors. Such capacitors are of way too small value to matter from a current standpoint, but they have a max rated voltage that should not be exceeded. So there could be a concern when using a 230V ballast with built in small capacitor at 277V

In practice there is no problem since it's mostly the US ballasts (277V) that contain such capacitors, so there is no problem to apply 230V to them. In the opposite case when using 230V parts at 277V - EMI capacitors normally have very significant voltage margins to withstand such abuse anyway, but in everyday use this may shorten their life



Inverter use :

Non pure sinewave inverters have significant harmonic components in their output. They will cause overcurrent in capacitive circuits, and very significant overcurrent in PFC capacitors (that are connected straight across the line)

Pure sine wave inverters have little harmonic components, but there may be significant high frequency (10's kHz) ripple in there. Such ripple may cause some overcurrent in PFC capacitors

With the pure sinewave inverters I wouldn' be affraid of the switching ripple that much. These components use to be rather low to start with, plus even few meters of xable add enough inductance (and damping resistance) to suppress the high frequency ripple current to a manageable level.
Definitely less stress than from a modified sinewave (MSW) ones.
Experience shows quite a lot of problems on MSW, but none on pure sinewave...

Thats interesting! I'd never thought that it would work both ways. I'm intending on trying to get some HID ballasts over. I thought I might check to see if it would work properly. I will still use something along the lines of a converter for if I can't find a 277V ballast. I knew that they sell step-down transformers but I knew that with mainly transformers you can go up in frequency but never down. How would it work if I were using a CWA ballast? Would it work as it should on 240 or undesirable effects with the capacitor?

what we did is get a US 12V inverter which gives us 120V at 60Hz. It runs off a 40A 12V supply I already had for my amateur radio gear.

I didn't want to go down that path as in my eyes it is really inefficient. First you have to convert it down to 12V then back up to 120V. I can understand that you are already running some kit off it and it makes sense using it. It could also work if you wanted it to work kind of like a UPS if you put a car battery or the kind of thing photon has in his cupboard

It's not all that inefficient. I ran a 100W H38 lamp on it and it drew 108W and about 8A on the 13.8V line. The PSU probably adds a few watts but not much and you know it's a genuine 60Hz supply.

The other use for the inverter is its intended use in the car. 120V is a lot safer than 240V outdoors and most kit works off 100-240V 50 or 60Hz now anyway.

I will still get a DC inverter for now but I'll still make a converter just as an excuse to make something.

I will still get a DC inverter for now but I'll still make a converter just as an excuse to make something.

Sounds like a plan, making stuff is good 

Ensure that any inverter you intend to run magnetic ballasts from is a pure sine wave one. The Wagan one I have is excellent and will run a 400W load all day.

I've considered building a similar setup to run my 240v 50Hz lights. I have a couple of spare 12v 30A power supplies that I could hook up to a 240v 50Hz pure sine wave inverter and get a proper 50Hz supply. Just need to source a affordable good quality 240v 50Hz inverter.

For long term use/higher current draw I would buy a proper frequency converter but they're rather expensive for testing low power lights. And most modern frequency converters are basically a rectifier combined with an inverter anyway, well unless you happen to buy a MA set.

Thats interesting! I'd never thought that it would work both ways. I'm intending on trying to get some HID ballasts over. I thought I might check to see if it would work properly. I will still use something along the lines of a converter for if I can't find a 277V ballast. I knew that they sell step-down transformers but I knew that with mainly transformers you can go up in frequency but never down. How would it work if I were using a CWA ballast? Would it work as it should on 240 or undesirable effects with the capacitor?

Same applies to HID chokes and HX, while all the more complicated considerations apply to the other types of ballasts

For chokes, the rule is that you dont want to saturate it. The flux (which if exceeds the designed value, leads to saturation) is related to the current. The current is proportional to voltage and inverse to frequency. So as long as V/F (new) is not higher than V/F (original), you are in the clear

Transformer can be viewed as a combination of 2 devices :

 - The "transformer itself" i.e. the voltage conversion according to number of turns. This works always regardless of anything else (as long as it is supplied with AC)

 - The magnetization of the core, which acts as a choke. This is, in fact, the choke which consists of the core and the primary winding of the transformer. The magnetization current is the current that goes in the primary winding when there is nothing connected to the secondary (which is, in fact, a choke - consisting of the transformer's primary and the core). This current is largely independent of the load on the secondary. (When the transformer is loaded, the current in the primary is sum of the magnetization current which remains the same + the current which is converted to the secondary)

In the case of choke (designed to act as a choke), the current through it directly affects the current through e.g. lamp, so we just want the current to be the same

In the case of transformer, it is designed to work at a certain magnetization level. If the magnetization will be too high, it will saturate. If lower than designed, it will be able to convert less power, but nothing bad happens

As the magnetization acts as a choke, the current through it is proportional to voltage and inverse to frequency. So, if V/F (new) = V/F (original), the magnetization current will be the same



CWA ballast have 2 components that behave different than a choke :

1. The core of the ballast
A CWA is a magnetic device with some interesting functionality. It is not "just a choke" like a choke or choke-derived ballast designs (HX)

The core of a CWA consists of a thin section of core in the magnetic path of the secondary, which is intended to saturate at a specific flux level. As the magnetic flux is converted back to electrical current on the secondary winding, this behaves as a constant current source (as in constant RMS value, not as in DC)

A gapped shunt between the primary and secondary windings then closes the magnetic circuit for the rest of the flux generated by the primary, which bypasses the secondary

2. The capacitor
As stated before, the capacitor behavior at different frequencies is opposite from a choke

Yeah proper frequency converters aren't cheap. The inverter I have was $99 plus shipping, and as I already had the 12V supply, which is capable of 32A continuous load with a peak of 40A, it was the obvious choice after I saw a guy on Youtube use one to run a vintage wire recorder.

I found a few schematics online for full sine inverters. One even went up to 96V ! I'll see if I can adapt it to work off 170V DC. I will see what I can do with that circuit, if all goes well I'll put it in a power box I want to make to output different standards. 240V In and will put that out for different standards: UK, German EU. I will also have 120V both 50Hz and 60Hz. I can buy a step down transformer and have the 50Hz and tap off that to go to an outlet and then rectify it and convert it to 60Hz. Its an elaborate idea but sounds like fun to make. I know exactly who you are referring to... Techmoan! I do remember watching his video of the wire recorder. I was talking to my dad (who's an electrician) if they made any devices that could do what I wanted and he kept suggesting that I use a step down xfmr but I kept saying that you can go up in frequency but not down and if I want to get any thing with a synchronous motor I can forget it .

That sounds incredibly complicated, best of luck 

The inverter was the cheapest and most practical method for me, as I already had the big DC power supply. Yes it was Techmoan, he's good, I love watching his stuff. It's pretty much the same inverter as mine, I think his is a slightly earlier version though, the one I have has a very slight difference in the design of the housing, there are a few other tweaks as well, I believe.

Ibe been running my British light collection prolly one of
Largest in the US.  60 Hz will run fine on 50hz but not the other way around in most cases.  The only problem I have is a capacitor in series with the chokes on my pop pack 8 foot fluorecent drawing 1. .25 A due to 60 Hz.  I have made correction by lowering from 7.2 uF to strong 5 uF cap 6 uF is ideal to run British 8 foot tubes on 60 hz
But i chose a 5 uF as it bring current down to 790 mA and
 Run philips and sylvania tubes by poping of the RDC caps and use it in my 8 foot pop pack. Now that light . with
Series cap is set for 60Hz operation at lower current running lamp at 108 watts,  and ballast is taking a retirement after a hard life over 40 years of service at reduce current.

 Now on 50 Hz this where I can see thing go wrong esp with magnetic rapid start and CWA ballast that current will go other way with those series to lamp cap set up.  So that means getting your current meter out adjusting your CWA cap to run your lamp correctly on 277 volt tapping
On hid ballast. Electronic ballast there rated 120 to 277 volt 50 / 60 hz.

Now and then on Ebay u can find 50 hz US made rapid start ballast.