Sizing TVSS (Transient Voltage Surge Suppression)

[SDV3]

Can someone give me advice with respect to sizing TVSS to my facility?? I have been told by some manufactures that fusing of TVSS product is a weak link others tell me its the only way to go. One manufacture explained that fusing has a direct relation to clamping voltages he explained that the each time a transient hits a fuse link that the clamping voltage continues to creep up he also stated that a TVSS unit should have repetitive abilities and that by having a fuse in place limits this ability, because once the fuse clears you are no longer protected.

Thanks for your time

 

[jbartos]

Suggestions:
1. Search this Forum for good postings on TVSS
2. My previous posting included:

http://www.itvss.com/techfaq.asp

http://www.itvss.com/subpage.asp?pageid=5

http://www.itvss.com/subpage.asp?pageid=26

http://www.gensemi.com/product/AppNotes/appnotes.htm

http://www.gensemi.com/appnotespdf/tvs_sche.pdf

http://www.gensemi.com/appnotespdf/quik102.pdf

http://www.gensemi.com/appnotespdf/auto_tvs.pdf

http://www.gensemi.com/appnotespdf/quik104.pdf

http://www.littelfuse.com/ASP/news/Detail.asp?id=137

etc. for more information
3. The TVSS is rated in Joules=Wattseconds. 160Joules=160Wattseconds. If your voltage spike produces Joules = Integral from 0 to t in seconds of (current x volts) x
dt of energy which is less than 160 Joules then the specified TVSS is adequate. Some design margin is prudent to incorporate depending on a repetition of spikes in time. E.g. Joules = 100 spikes x integral from 0 to 0.00002 seconds of (90 volts x 10 amps) dt = 1.8 Joules, which leaves good margin to 160Joules. However, if there happen to be 10000 spikes in succession, then resulting 180Joules will exceed the rating of your specified TVSS. This may end up in a thermal runaway. Therefore, one must have a good idea about number of spikes in the succession and TVSS ratings. Continuous spikes must then have a TVSS sufficiently sized so that the heat dissipation takes place. The above calculation is approximate, only for illustration. When a number of spikes is unpredictable, then the selected or estimated TVSS may burn, which happens.

 

[nongeek]

I have two questions regarding TVSS:

I would like to know wheher the effect of installing TVSSs across all branch panels can save energy?

Will a 380V motor and a 1000V motor, with other specs same and running a same period of time, consume same amount of power? Reall need help on this.

 

[cbarn24050]

A point about fusing, if the tvss fails due to overload they allmost allways short, then they explode if you don't cut off the current.

 

[dpc]

For nongeek:

TVSS devices do not save energy.

Equal size motors with equal efficiencies driving the same load will use the same amount of energy regardless of voltage.

 

[Traveller]

All right. Suppose the load dramaticlly inscreases due to frenquent surges and spikes and operating temperature goes up? Will that consume more energy compared to a smooth, trouble-free condition?

Can TVSS be used together with harmonic filters for better power quality?

Thanks.

 

[melone]

All a TVSS can do is eat voltage spikes. It sounds like you want some series inductance to minimize current spike and a TVSS to minimize voltage spikes.