I've been interested in learning about the older and more obscure power systems used in history. About a year or two ago when researching 25 cycle (Hertz) power I learned that there were in fact special 25 cycle lamps, let alone ballasts. Has anyone had a 25 cycle lamp or even a 25 cycle ballast in their collection? The 25 cycle lamps will work on 60 cycles (and vice versa) as the 25 cycle lamps had a guard over the cathode ends to stop the light from being emitted from the cathode end to reduce the visible flicker from the lamp as the ends would flicker very badly on 25 cycles.

I think these systems had to be rare as Buffalo went to 60 cycles in the 50s, but they had 25 cycles in Arizona until the 70s I think. Remember there was even flicker on incandescent lamps at such a frequency.

There was a plant that my aunt took me to for a tour went i was a kid,  it had 25 cycle electricity the fluorescent do indeed flicker badly but people worked
There hardly notice, it would drive me nuts as on 3 phase. 25 hz the lights look like a xmas chaser set on
The celing. There are a few places that still used 25 Hz
Power as i know of a alum ore processing plant
Cause they use a lot of power for burning off the alum oxide in the process to make aluminum.

Yes, many places still use 25 cycle power for machinery, but the frequency is converted on site, it is very unlikely that it is used for lighting anymore. Amtrak also maintains a 25 cycle system for trains in the northeast corridor, but the last public utility system was discontinued in 2006 as the customers did not want to pay for repairs and part of the 25 cycle tariff required the customers to chip in for any repair exceeding a million dollars.

I'm wondering if anyone has a 25 cycle ballast or lamp in their collection.

Anyone who lived in Fort Erie, ON in Canada and closeby who used to be on the Canadian Niagara Power Company (now FortisOntario) grid, would have been on 25 Hz power until 2002.  Power was generated at the Rankine Generating Station just upstream of Niagara Falls on the Canadian side.

Wow, pretty much everything except incandescent lamps, heating appliances, and maybe universal motors had to be made specially for 25Hz.  It would be interesting to see any kind of lighting or any other appliance designed for 25Hz.  My Dad's old Skil saw (circa 1970) is rated for 25-60 Hz.  I think the New York City subway's AC power distribution system (before step down and conversion to 600VDC) is 25Hz, but that's a closed system that doesn't need to work with general household appliances.

Matt

Hi it might interest you to know that here in the UK we had different frequency's between 20 and 100 cycles gradually standardized by the mid 60s at 50 c/s voltages were between 190 and 250 single phase I've seen old Florry lamps with tapped chokes to cater for this
T

Very interesting to know! Never heard of them myself!

Wow, pretty much everything except incandescent lamps, heating appliances, and maybe universal motors had to be made specially for 25Hz.  It would be interesting to see any kind of lighting or any other appliance designed for 25Hz.  My Dad's old Skil saw (circa 1970) is rated for 25-60 Hz.  I think the New York City subway's AC power distribution system (before step down and conversion to 600VDC) is 25Hz, but that's a closed system that doesn't need to work with general household appliances.

Matt

The NYC subway was actually a mix of 25 and 60 cycle current, but they ripped out the old 25 cycle rotary converters and replaced them with more modern rectifiers and converted the entire subway to 60 cycle current. Many subway stations ran their lights on the 25 cycle current.

London underground used to run some of the fluorescents in the stations from the traction DC supply this resulted in mercury migration to the anode end of those tube so every six months or so the electrician would turn all the DC tubes round to get the mercury back again. Im not sure how you would run a 250 volt light fitting from 630VDC but obviously they new a way

They probably had a 630V to 230V step-down transformer for the lighting. I wonder if some relays with an automatic timer could have switched the current direction periodically instead of paying electricians to reverse lamps in the sockets. This reversal could have been programmed for every day and the result would have been less mercury migration and probably more light.

On the other hand, 25Hz lighting would have had very pronounced flicker at 50Hz instead of using standard 50Hz mains with flicker at 100Hz.

The DC ballasts were just a resistor and inductor common for few lamps in series and an electromagnetic starting contact separate for each lamp (in fact forming a preheat circuit).

Otherwise quite common methods were rotary converters

But connecting the station lighting to a traction power seems quite strange to me: The traction power is subject to dips and fluctuations caused by the high current draw of the train motors, so the lighting connected there would be quite flickery. Plus with any small accident you have to shut down the traction power for the section and that would mean loosing the lights as well...

@sol: Just a transformer won't work on DC...

London underground used to run some of the fluorescents in the stations from the traction DC supply this resulted in mercury migration to the anode end of those tube so every six months or so the electrician would turn all the DC tubes round to get the mercury back again. Im not sure how you would run a 250 volt light fitting from 630VDC but obviously they new a way

The rules for DC operation were quite well known, but in this case not followed exactly. GE stated that every lamp over a certain length (24 inches IIRC) required a switch that alternated polarity at every switch on to prevent mercury migration.

The lamps on the stations were mostly run from the normal 240 volt 50c/s mains just a few were run from the traction DC it was done so that which ever system had a fault the other lights kept going.

A universal or even some compound wound DC motors will run fine from 16-25 Hz AC current.This is why that sort of power was chosen for electric locomotive use.You can transmit and transform it as AC-but its a low enough frequency so DC motors can run off it without rectifiers.Thought ALL of the 16-25 Hz power was discontinued at this time.Modern electric locomotives can run off multiple voltages and power.They now operate from 60 Hz or DC.New locomotives have this capability-or they can run from 16-25Hz if it is still used.A RR magazine I used to subscribe to say the 16-25 current was discontinued and the equipment and conversion gear removed and the electric railroads now run off 60Hz.No more 16-25 equipment to maintain.The new locomotives have VFD drives for their AC traction motors.-So the incoming power used in them is rectified anyway for the motor invertors.

The motors can operate at the 25Hz, but that supply was used only (as far as I know) on main train lines (to allow the use of higher voltages, like 10..25kV, because it was possible to convert by a transformer; having a motor running directly on such high voltage is not possible due to commutator arcing, so the voltage had to be always converted to something not more than 3kV), not in the city systems.

Most city systems use just DC as the main traction power. The reason is, the efficiency of the series/compound motors at 25Hz is way lower than at DC, while the distances and power levels won't justify the use of an onboard transformer anyway (it's mass would mean extra power demand to carry it's mass, so that could be viewed as additional extra losses), compare to the plain DC power system.

On the main railway the 25Hz (and most of the others low frequency) systems start to disappear, once the lightweight rectifiers for onboard use become available - then the 50Hz transformer becomes lighter and the rectified power was DC, so efficient motors. Plus no conversion from the normal mains (except again a transformer), so less losses there, all that mean the sub-mains frequency systems are just an old legacy.

Of course today the motors itself are again AC, but need the upstream variable frequency inverter, so the inverter + motor compound should be viewed as single unit and that unit is again powered mainly by DC anyway...