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KB2VXA > INFO 18.07.02 13:13l 44 Lines 2090 Bytes #999 (0) @ WW
BID : 50438_WT3V
Read: DB0FHN GUEST
Subj: Re: GM7HUD > US MAINS VOLTAGE
Path: DB0FHN<DB0ZWI<DB0HDF<DB0ABL<DB0HOT<DB0MRW<OK0PKL<OK0PPL<RZ6HXA<SP7MGD<
SR3BGN<WB0TAX<N4ZKF<N0IA<N0IA<K1UOL<K1UOL<WA2SNA<KB2VLX<<WT3V
Sent: 020628/1855Z @:WT3V.#JS.NJ.USA.NOAM #:50438 [Lakehurst] $:50438_WT3V
From: KB2VXA@WT3V.#JS.NJ.USA.NOAM
To : INFO@WW
Hi Andy and all,
The US "standard" for mains voltage can be quite confusing! You refer to
residential "house current" primarily so I'll start with that. It used to
be 110, then 120, then 117 and now "they" seem to have settled at 115.
Under varying supply and load conditions it can vary from 110 to 120 so
when measuring at the wall outlet there can be no practical standard.
It's supposed to be 115 nominal + - 6% so when the system "browns out"
under peak load conditions to keep equipment from frying it usually is
110 volts. Residences are supplied normally with 230 volt, single phase
for heavy appliances and is divided at the service entrance panel into
two 115 volt legs for lighting and small appliances.
The exception is appartment complexes which are usually supplied by a 208
volt wye (as opposed to 230V grounded delta) 3 phase hookup which
supplies 208 single phase for heavy appliances and 115 single phase for
lighting and small appliances.
"Heavy duty industrial strength" current is suppled in older
installations by 230V grounded delta 3 phase which can be divided at the
panel into 230 single phase, 115 single phase and 170 single phase for
special lighting circuits. Newer installations are supplied with 208 wye
which is divided as above. Please note that 230V and 208V are almost
completely interchangable due to the 6% tolerance.
In bigger installations, the power is 440 3 phase wye and is divided by
transformers to preserve the ground configuration. Other voltages are 660
and 880 but these are seldom used.
In most cases the supply is from 4800 volt 600 amp 3 phase primaries.
Very large installations are supplied by even higher voltages from area
distribution feeders which can run into the hundreds of kilovolts.
*********************************
I'm a technician, not a magician!
*********************************
73 de Warren, KB2VXA
e-mail: kb2vxa@juno.com
Message timed: 18:55 on 28 Jun 02 UTC
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