We are getting ready to install some Computer network equipment purchased Stateside 120vac 60hz in a office in Hong Kong 220vac 50hz. How can we adapt this equipment to work there. Some of the devices have plugs with transformers on them?

Can we use the adapters sold in stores to do this?

If they're the "wall wart" type of plug-in power packs, then you can probably find suitable 220V replacements locally in Hong Kong quite cheaply. Just check for AC/DC output, correct voltage and regulation, current, and connector type/polarity, and you should be fine. Even if the existing power packs output AC which is rectified in the equipment, it's unlikely that the 50/60Hz difference will be of any importance.

If you have a whole bank of equipment or anything with a built-in 120V-only PSU, then it may be easier/cheaper to obtain a 220-to-120V transformer of suitable kVA rating and run some regular NEMA 5-15 outlets from it for your apparatus.

Just want to be sure because we are installing a Server I have seen some of the available step down transformer devices that go up to 2000 watts. Just wanted to be sure that the 50hz won't affet the operation of a Server. I appreciate your response.

If the equipment is so labeled to permit higher-voltage/lower-frequency power, [typical of a lot of switchmode stuff] can't you change IEC320(C13) cords from NEMA5-15P to whatever’s needed to fit the local-HK receptacles?


[This message has been edited by Bjarney (edited 06-22-2004).]

Advice:
Buy a decent step down transformer at Ap Liu Street(Sham Shui Po MTR,Exit C). Never buy the cheapo in neighbourhood shop.

I'd check to see if the server PSUs can be voltage switched.

Look for a slide switch near the power cord connector on the power supply. Usually marked "120-240", and is usually colored red. This switch is designed to require a screwdriver or similar tool to change, and not be easily changed by an unaided hand. It may be hidden behind some plastic trim on some computers or servers.

If the supply isn't the usual PC power supply, and you can take the cover off the server, the power supply might have a jumper wire to choose 120V or 240V operation.

The above switch or jumper just configures the supply from a voltage doubler to a bridge rectifier. This is to get around 300VDC that is then fed to a high frequency chopper, then high frequency transformer, and then rectifier circuits to get the 5VDC.

Switching power supplies don't care if it's 60Hz or 50Hz. And the server won't care either.

The server PSU will likely be switchable this way, but check the monitors. Some may be internally configurable for 120 or 220 operation, even though they seldom have a an accessible external selector.

Some of the latest monitors auto-adjust and will actually run on anything from 90 - 250V with no manual adjustment necessary.

Guys I appreciate the response we bought a 5kw voltage stabilizer / step down transformer to do the trick.

Also if you do not see the voltage selection switch take a look at the power supply label. Some power supplies are designed to be auto-range so they accept 90~135V or 180V~260V. They also adjust for frequency of 47~63Hz.