DIYbanter - View Single Post - Check your HVAC surge protector -- fail reports

bud--

On 10/26/2015 11:01 AM, wrote:
On Mon, 26 Oct 2015 06:52:48 -0700 (PDT), westom
wrote:

On Monday, October 26, 2015 at 12:19:21 AM UTC-4, Muggles wrote:
This is an interesting topic, for sure, and I'm just dipping my toe in
it when there's a whole ocean of information.

Unfortunately, protection is about earthing - not about oceans.

That is westom's apparently religious belief, immune from challenge.
Protection is about keeping the voltage between wires at a non-damaging
level, which may or may not directly use earthing.

Since plug-in protectors are not well earthed, westom believes they can
not possibly work. With minimal reading skills he could read in the IEEE
surge guide that they work primarily by limiting the voltage from all
wires to the ground at the protector, and that plug-in protectors are
effective. But westom just ignores conflicting ideas. He is the poster
child for cognitive dissonance.

If you have a large surge current to your house's earthing system, the
"ground" potential and the building power wiring may rise thousands of
volts above 'absolute' earth potential. That may be thousands of volts
from the cable/telephone/dish/... wiring, depending on how they are
protected. Keeping the voltage between all wires at a reasonable level
is more important than minimizing the voltage to 'absolute' earth potential.

The frequent lightning strikes to airplanes are much more extreme cases
where protection is by voltage limitation, and where an earth connection
is not even required (or possible).

Simple surge protection ( not talking ligtning) can also be simply
clamping the voltage line to neutral with no ground involvement.
Varistors do this quite effectively. A more accurate description of
the power anomoly we are talking about is a "transient" - and the
devices are often referred to as "transorbs"
They (the anomolies) can also be referred to a "pulses".

"Transient" is likely the same as "surge". "Pulse" is rather ambiguous.
Protection from surges caused by lightning is not rocket science.

MOV Transorbs can be connected line to line, line to neutral, or line
to ground.

Transorbs are not MOVs (metal oxide varistors). In transorbs the voltage
limitation occurs at a semiconductor junction. MOVs have the voltage
limitation at grain boundaries throughout the device, which spreads the
heat from limitation over a much larger volume. That is why MOVs can
operate at very large currents (for a very short time).

UL listed plug-in protectors will have MOVs from H-N, H-G, and N-G. If
signal wires go through them they will also have voltage-liming from
those wires to the device ground.