TVSS Applications

[hogdawg]

I was wondering if anyone has had experience with application and ROI with these guys. The input I've received thus far is how did we ever get along without them! My application is shipboard.

Thanks

 

[Skogsgurra]

Tons of thin air there. Of course, transients can harm. But this is pure "sell by fear". And words, words, words. Some of them not very convincing. Like this snip from "What are surges?":

"Inductive coupling
Whenever electric current flows, a magnetic field is created. If this magnetic fields extends to a second wire, it will induce a voltage in that wire.......

Magnetic coupling
Wires that run adjacent to one another in a building can magnetically couple transients."

It is interesting to learn (after 30+ years as a transient-fighter) that there is a difference between magnetic coupling and inductive coupling. ;-)

There is nothing new in that site. And the presentation is not very convincing. Some marketing guys that are under too strong influence of a technical guy (the opposite is usual). As I said, too much words and very little new facts - if any.




Gunnar Englund

http://www.gke.org

 

[OperaHouse]

If you look at the literature closely for MOVs, you will see that they are all done with one inch leads. That doesn't reflect real world installations. They are nice for a lot of low level stuff like motors. Most equipment can take 6KV pulses easily. A while back the military noticed they were actually having more failures (MOVs themselves) in equipment and raised the voltage spec. I use them, but still the STP of the electrical world.

 

[itsmoked]

OperaHouse; Interesting analogy. I like it!

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[coconutalley]

In my other life, I designed surge protectors for computers, telephones, TV, and networks for a manufacturer that sold millions of units. Had experience evaluating returns of damaged surge protectors. Lightning generated surges are the most damaging.
Yes, I agree there is a lot of marketing hype out there but
equipment can be designed to be protected against transients. There are pros and cons just like anything else.
Is the ship electrical system isolated [floating wrt to the ship steel structure], or grounded via impedance to the structure?

 

[Comcokid]

In the old days most items were powered through a linear supply and the transformer provided a good deal of protection and the filter capacitors supressed any transient that got through. Power switches were just that - power switches that completely broke the incomming power.

Before the old days, the active devices were tubes, and the linear power supply even had a tube rectifier. Forget transients - these are even immune to EMP!

Nowdays, efficient swithing power supplies are used, and in most equipment the power switch is a "power request" to a always-on circuit. These are exposed to incomming transients even when you would think they are OFF, and there are plenty of semiconductor devices associated with the primary side of the supply.

Skogsgurra - Maybe the author of the article didn't know the difference between "Magnetic Coupling" and "Capacitive Coupling" !

Coconutalley - It's great when you can design everything in the equipment, but frequently you're forced to buy out-of-the-catalog power supplies, the the supply guys compete for the last penny frequently cutting corners on the voltage rating of parts down to just what's necessary to meet the approvals.

I did a lot of design of electronics for off-road industrial vehicles , and transient protection for a alternator-sourced voltage is a big issue. It would probably be easier powering from a lighting bolt! Magneto sourced supplies (ATVs, watercraft, etc) are even more fun! Glad I'n not doing that anymore.

 

[electricuwe]

Basicly you need to put in some means of Overvoltage protection to comply with EMC-standards (ESD, Surge, Burst).

TVSS are one of many devices available for that purposes. You have to choose according to the requirements of the standard. Since the standard does not specifiy the use of a certain device but the fulfilment of a requirement there is some engineering work to be done.