On Oct 19, 2005, at 1:13 PM, Tony King - W4ZT wrote:
> Seems a lot of folks have opinions and that is a good thing. Perhaps I
> am just a little more anal about keeping wires cool (yes, I HAVE had a
> house fire). Fortunately it wasn't caused by under sized electrical
> service.
>
The last house fire in this neighborhood was caused by rodents eating
the vinyl insulation on electrical wires. This happened after the new
owner of the house decided to get rid of all the cats living on his 2.5
acres.
> Gudguyham@aol.com wrote:
>>
>>> In a message dated 10/18/2005 8:22:50 PM Eastern Daylight Time,
>>> aa4lr@arrl.net writes:
>>
>>>> W4ZT wrote:
>>>> Now let's try 240 volts
>>>> which would give us 2944/240=12.3 amps. If your line voltage is
>>>> low and
>>>> you have 220 volts the current would be 2944/220=13.4 amps. From
>>>> this
>>>> example it is obvious you can't run a full legal limit amp on even
>>>> a 20 amp, #12 wire, 120 volt circuit much less any 120/240 volt, 15
>>>> amp #14 wire circuit.
>>>
>>> Seems to me that 12.3 A and 13.4 A are both less than 15 A. So a #14
>>> circuit seems adequate for your example.
>>
>> FYI....An Ameritron AL-1500 will do 2300 watts output with 100 watts
>> of
>> drive. (FACT)
>> The AL-1500 comes from the factory with a power cord with a 240V 15A
>> power plug and is fitted with 15A fuses. A 240V circuit run to this
>> amp using #12 wire will run this amp at 2300 watts out with no
>> problems
>> in SSB and CW modes. Surely a 15A circuit will suffice at legal
>> limit.
>> The important thing here is the length of the run from the service
>> panel
>> to the outlet for the amp. If your voltage is way low, the Ameritron
>> has a low voltage tap you can use which ups the secondary voltage so
>> that current again is not an issue. An amp such as an SB-220 can
>> easily
>> be run on a 240 line run with #14 wire.
>
> If we use your factual example of 2300 watts OUTPUT, then using 60%
> efficiency will give us 3833 watts input power, add a few amp pieces
> for
> another 100 watts for 3933 watts. Use 90% efficiency for the power
> supply and you've got 4370 watts. That's 18.21 amps at 240 volts. Add
> a
> blower at an amp and you're up to 19.21 amps. #14 wire on a 15 amp
> circuit wouldn't be the right choice for your example. Actually,
> neither
> would #12 on a 20 amp circuit. Drop the mains voltage, change the tap
> in
> your power supply to maintain your B+ and your mains current is even
> higher.
>
> This is why I went through the exercise in the first place. There are
> always a few hidden current consumers in the amp and if you then choose
> to power the transceiver or other things from half that circuit you're
> unbalanced and higher yet. I wasn't trying to start a high level
> debate
> just a practical example of why a little larger wire is better.
>
> Each of us has to decide how much risk we're willing to take.
>
> 73, Tony W4ZT
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|