On 9/11/2012 3:55 PM, WD8ARZ wrote:
Most of the electronics in my home is protected by putting a UPS
(uninteruptable power supply) between them and the wall outlet.
Avoid the cheap low end low power units. They dont last long, fail
sooner, and can run hot.
Choose a size from a good vendor that has the capacity to run the items
it is powering for about 15 - 30 minutes with out AC power.
Those better models have excellent switching time, larger or multiple
batteries, run cool, and have excellent filters / suppression built in.
Plus many will adjust to provide the right voltage and 60 cycles needed
for more sensitive devices, especially computers.
When the UPS is going dead, it switches off giving a clean break to the
equipment.
So not only do you provide isolation and suppression of a lot of RFI
from switching power supplies, you also improve the survivability of
those switching supplies that are still powered on when the device they
run are off, thus making them vulnerable to power line transients.
Keep in mind that even though a lot of power supplies and electronics
have built in spike suppression from MOV's (metal oxide varisters),
those MOV's will no longer be working after several hits, even one large
event can disable them. Same for those external power strips with spike
protection built in. The better external power strips will have
suppression devices that include chokes / filter design, and not just
mov's.
Ups units are better choices as they have all the mov / filter / choke
designs in them, but also the battery that absorbs and isolates a lot of
problems, along with voltage / Hz adjustments.
Remember that these are no longer line conditioners. They neither
regulate, or filter the output voltage to the loads. They do have spike
suppression but they only use the battery to power the inverter inside
when the line voltage fails.
Line conditioners that generate a true sine wave, where the load
"always" runs off the battery which is continually charging from the
power line are available, but rare and very expensive compared to the UPS.
They will likely run about 3 times the cost of a top of the line 1500
watt UPS.
No, I cant say what UPS units to avoid or to get. That changes so much
in a short period of time as the models are changing all the time.
And it may depend on the model as well. I've used a range of APC models
typically in the 1500 VA range with no problems over quite a few years.
73
Roger (K8RI)
73 from Bill - WD8ARZ
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|