Wikipedia:Reference desk/Archives/Science/2022 May 25

= May 25 =

When does Hz or voltage difference matter?
For what devices does it make a difference whether AC is 60 or 50 Hz, or has some voltage variation (say 127 instead of 120, or 240 instead of 220). --Bumptump (talk) 15:34, 25 May 2022 (UTC)


 * Some clocks rely on the utility frequency to keep time. So if a clock is 'expecting' a 60 Hz AC supply but only gets 59 Hz AC, then it will lose one minute every hour.
 * Synchronous motors turn at a rate that depends directly on the frequency of alternating current supplied to them, so appliances and equipment that use them will turn slower or faster in proportion to the change in line frequency (assuming they're being powered directly by line current). Other AC motors may also change speed in response to a change in line frequency, though the change won't necessarily be linear. For some equipment, changing from 50 to 60 Hz will increase the load on components, and may cause increased wear and tear (or outright failure). TenOfAllTrades(talk) 16:36, 25 May 2022 (UTC)
 * For most modern consumer equipment, the voltage doesn't matter within about 10%. Indeed the european 230Vac is 220Vac on the mainland and 240Vac in Britain - with the official tolerances trimmed a bit. Where the ac supply is driving a power supply, the frequency matters little within maybe 20%. But don't put 230Vac into a device rated for 110Vac, it mnay blow up. -- SGBailey (talk) 17:18, 25 May 2022 (UTC)
 * Using 50hz when a transformer expects 60hz can overload the transformer from magnetic saturation. Back when dc-dc conversion was harder, weight conscious environments like airplanes used 400 hz AC powered stuff in order to keep the transformers smaller.  2601:648:8202:350:0:0:0:738F (talk) 21:25, 26 May 2022 (UTC)