UK-USA Mains Hz differences

[Shox Dr]

Another thread reminded me about a question that was asked last week, between a few of us.

Why is there a difference between the UK and the states in Hz. And does it have any effect on kit used on the different Frequency's (ies)

I've got a Bransonic Ultrasonic cleaner that I bought off US ebay, so it's 110v/60Hz, I had it for 10yrs, running it through a 110v/50Hz transformer and never had any problem with it. So what's the differences/pro's/cons

 

[tigler]

Depends on the equipment. Lower voltage means less shock hazard potential but higher operating currents, therefore larger conductor diameter required. Frequency wise, some stuff isn't bothered by the difference between 50 & 60 Hz, infact alot of thingsare happy on 50-400 Hz. Anything with an induction motor could have problems though as the operating speed of the motor will be higher on 60 than 50 Hz Anything that uses the mains frequency as a time reference standard will also be in trouble too. Like clocks, video's, etc. Why the difference in frequency between the States and the Uk is probably down to which organisation designed the original generators in each country.
Although, houses in the states do have a 220 volt supply in addition to 110 volts. 220 is for higher power consumption equipment.
Back in the day before the power grid in the UK, there were regional standards for voltage, and in fact some area's had DC mains, which remained in some instances into the 60's ! High voltage DC is really lethal stuff !

 

[rtbcomp]

The difference is because someone in the UK decided 50 Hz was the frequency to use, his counterpart in the US decided on 60.

AC motors will run faster on 60 Hz, I used to work on American equipment that had larger motor pullies fitted for use on 50Hz. Sometimes motors designed for 60 Hz would run too hot on 50Hz.

Transformers are more efficient at higher frequencies so on a given transformer you would get higher secondary voltages on 60Hz. This can be compensated for with tappings.

On electronic equipment the voltages regulators could compensate for voltage differences, so USA equipment would bo OK over here. Modern switch mode power supplies are better still.

In power distribution, transformers can be smaller, but there are greater losses due to capacitance on power lines.

 

[madkayaker]

Stuff from the us will work here but stuff from here will go bang on the higher frequency! high voltage DC is hellish stuff but apparently 50hZ is more damaging than 60hZ for us as it closer matches our internal frequency for heart etc.

 

[awemawson]

"Transformers are more efficient at higher frequencies so on a given transformer you would get higher secondary voltages on 60Hz."

Well yes transformers are able to handle more power at higher frequencies, but the voltage output is entirely set by the ratio of turns on the primary to the turns on the secondary. A transformer designed for 50hz to transform 240 to 115 will still give 115 out if the input is 60hz 240v and vice versa. The cross sectional area of the core determins the power rating of a transformer, and the higher the frequency the smaller core you can use. This is why inverter welders are so light. They rectify mains to DC then chop it at a high frequency allowing the use of smaller transformers (usually ferrite cored rather than steel laminations)

 

[Drains]

Japan has both systems - 115v/60hz in the South/West, and 240v/50hz in the North/East. To confuse.

 

[Robotstar5]

Japan has both systems - 115v/60hz in the South/West, and 240v/50hz in the North/East. To confuse.

I bet that makes shopping near the border a nightmare!

 

[the snooper]

infact alot of thingsare happy on 50-400 Hz

surley that must be a typo 400Hz
the power generation companys always maintain the frequency rather then the voltage.
and the rewind specialist i use go out to quite a few governor failures where the genny has gone over the 50Hz and fried motors and stuff.
i also have a mate that lives on a barge and his genny was playing up so he decided to give i a quick rev which resulted in his tv smoking, so i find it hard to believe that most stuff would run on 80Hz let alone 400, thats a huge increase

 

[shenion]

Most switching supplies (like used in a PC) will run 50-400Hz. They rectify to DC first, so the frequency really does not matter.

400Hz is used on aircraft and military equipment.

As for generators, ones like I had, have a zener that shorts the field. If the RPM goes up too high, the circuit will have to dissipate too much power. Others will generate too high a voltage if the frequency is hot close.

 

[tigler]

No typo, alot of stuff is designed to work on that frequency range because of adaptability with global markets and military supplies. If you look on mains adaptors supplied with small appliances it's not unusual to see this. Most modern test equipment is also compatible with such supplies.

 

[Drains]

surley that must be a typo 400Hz
the power generation companys always maintain the frequency rather then the voltage.

They do, but I'm not sure that the two are not linked in other circumstances (eg on an AC alternator) - I know that my old Honda genny would run under volts if it was running slow, and over volts if it were running fast. 50 Hz would match up with 240v.

 

[madkayaker]

We have 400hZ stuff at work. A 4kw motor is about the size of a coffee mug

 

[the snooper]

on a small genny 3000 rpm is 50Hz and voltage is regulated either by capacitor or by an AVR the commercial power companies do have a tolerance for frequency.

National Grid has statutory obligations to maintain the frequency within +/- 0.5Hz around this level. However, National Grid normally operates within more stringent 'operational limits' which are set at +/- 0.2Hz.

the above was taken from national grid website
the voltage regulation i think is less strict

 

[the snooper]

We have 400hZ stuff at work. A 4kw motor is about the size of a coffee mug

yes but they are a speciality you cant just plug into the national grid and run it at 400 Hz without its own special power supply

 

[madkayaker]

It gets worse the 200v 3ph!