Re: surge protection for cart


"G. John Garrett, C.A.S" <jg@xxxxxxxxxxxxxxxxxxx> wrote in message
news:dI6dnRPSa8EgxBnanZ2dnUVZ_rignZ2d@xxxxxxxxxxxxxx
w_tom wrote:
On Jan 7, 12:17 am, "Richard Lightstone,C.A.S." <aut...@xxxxxxxxxxxxx>
wrote:
A line conditioner will monitor the incoming line voltage and prevent
a severe voltage spike from damaging your expensive gear.
You're lucky that the Powermax was the only piece of gear damaged.

The cited Furman is properly identified by others as gobbldygook.

Based on what? From my experience its a decent power conditioner and has
made a dramatic difference in my application. There are MOVs, lowpass
filtering, overvoltage protection and separate surge protection devices.


John

Power conditioning for consumer equipment is a different application. A MOV
based device provides some protection. Nevertheless, this is not a wave
tracking unit. It has pass-through.
The problem with buying buzzwords is similar to self-medication. It misses a
lot of engineering level detail. Here's one:

There are two types of surges: normal mode, and common mode. Normal mode
raises the voltage on line, but not neutral. When the MOV on that branch
conducts, it causes the power wiring to the point to act as a voltage
divider. Let's get specific. Suppose the incoming surge is 1600 volts. The
MOV clamps the difference between hot and neutral to 330 volts, BUT the
voltage at either HOT or NEUTRAL, with respect to GROUND, is 800 volts,
which would be clamped by the the other two MOVs to 330V if the GROUND had
no resistance. But it does. Thus even a normal mode surge "lights up" the
ground at the equipment, raising it to a voltage determined by the gauge and
inductance of the ground wire, INDEPENDENT of the clamping voltage of the
MOVs.

If the equipment is connected by a cable run to other equipment, which is
either not grounded, or grounded at a different point, the surge impresses a
large spike on that cable run. Under some conditions, it can be dangerous,
but it certainly is an equipment destroyer. And it's even worse in the case
of common mode strike.

It can be dangerous if you are operating 3-wire connected equipment with
metal chassis parts, and you are simultaneously grounded to a different
point, such as damp concrete, or somebody else's equipment, etc. This
danger exists in the absence of a lightning strike.

All MOV and Transzorb based surge protectors light up the ground, because
they are shunt-based systems. A consumer entertainment system is usually
plugged in and grounded at a single point. In professional applications,
this is not always the case.

Wave-tracking systems are not shunt-based. They do not light up the ground.
A number of recomendations have been made in this thread regarding
manufacturers of these systems.

Bob Morein
(310) 237-6511





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Relevant Pages

  • Re: Does a MOV shunt current or equalize voltage?
    ... A MOV across a relay coil shunts nothing to ground and protects entirely by voltage limitation, absorbing the energy stored in the relay coil. ... For a service panel suppressor, with a MOV from hot to neutral/ground/earthing-electrode-, say a 10,000A surge arrives on a hot service wire. ...
    (sci.electronics.design)
  • Re: whacked by asploding transformer, part deux
    ... finally tore down my dishwasher today after getting sick of doing ... stuff in my house (a surge strip, an electrostatic air filter, and my ... Am I correct in assuming that this is a MOV? ... when the voltage returns to normal. ...
    (alt.home.repair)
  • Re: whacked by asploding transformer, part deux
    ... finally tore down my dishwasher today after getting sick of doing dishes ... replaced the surge strip and the TVSS breaker that was in my main panel ... MOV, is value important, or simply "bigger is better?" ... The mov is basically an open circuit and shorts out when a voltage higher ...
    (alt.home.repair)
  • Re: Help With a MOV (Varistor?)
    ... They will prove that the power line is at fault, ... I realize that the MOV won't give great ... > protection for the equipment, but I like 'em to be in there anyways. ... >> trust a surge suppressor power strip to protect your equipment. ...
    (sci.electronics.components)
  • Re: belkin power conditioner for my Samsung LCD - is it worth it???
    ... The rise time is lowered by | the impedance of the source wires. ... Plug-in suppressors handle any mode surge. ... The MOVs protecting between line and neutral will not see much voltage ... across them because in common mode, both of those wires will have the ...
    (alt.tv.tech.hdtv)