TVSS

[steve66]

Can a TVSS be connected with a tap conductor? I have a fire pump with a 600A breaker that is wired with #1 conductors. Can I land a set of #2 conductors on the 600A breaker and feed a surge suppressor without another breaker? The suppressor will only accept wire as large as #2.

Also, does anyone understand:
1. Can suppressors be installed on the line side of the service disconnect?
2. What is meant by "power frequency voltage" in 280.4?
3. How do I know what the AIC rating is for a paticular surge suppressor? (per 285.6). I don't see that in any specs.
4. I don't understand 285.21? It looks like this prevents me from installing the device on a sub-panel? It says it has to go on the main disconnect?
5. How do I nkow if article 280 or 285 applies to my device?

Thanks:
Steve

 

[dereckbc]

Re: TVSS

Q. Can a TVSS be connected with a tap conductor?
A. Yes, provided you have a TVSS with built-in disconnect and OCPD.

Q. Can I land a set of #2 conductors on the 600A breaker and feed a surge suppressor without another breaker?
A. Yes, if the TVSS has built in disconnect and OCPD.

Q. Can suppressors be installed on the line side of the service disconnect?
A. Yes, with OCPD.

Q. What is meant by "power frequency voltage" in 280.4?
A. The continuous voltage between DC-to-400 Hz.

Q. How do I know what the AIC rating is for a particular surge suppressor? (per 285.6). I don't see that in any specs.
A. By the specs, and face plate. If it is not listed or marked, it is not compliant. Not all TVSS devices are compliant.

Q I don't understand 285.21? It looks like this prevents me from installing the device on a sub-panel? It says it has to go on the main disconnect?
A.It just means it has to be on the load side of the service disconnect over current device. To verify read 285.6, it refers to TVSS receptacles.

Q How do I know if article 280 or 285 applies to my device?
A. By which side of the service it is on. Line or Load. Surge Arrestors (280) are line side. TVSS (285) load side unless listed as both Surge and TVSS

[ June 10, 2004, 08:31 PM: Message edited by: dereckbc ]

 

[snjeza]

Re: TVSS

If you contact Liebert corporation they will help you.
I have some Liebert broshure on TVSS and The Emerald Book: IEEE Recommended Practice for TVSS - just one page... if you want post your email and I will forward you.

 

[hbendillo]

Re: TVSS

1. Yes, if they are rated for such use. It may require more than just an OCPD. Check with your manufacturer.

2. Don't know.

3. Some manufacturers provide the info in the specs but can certainly tell you if asked. You will probably find the units are rated very high to match the application for which they are generally used. There are Category A, B and C ratings for suppressors that are related to where they are installed in the distribution system. You will probably find the AIC rating to be on the high side of what is typical for those points in the distribtuion system.

4. You can install TVSS's throughout your distribution system, not just at the main. I think they are emphasizing that it should be installed on the load side of the main breaker if installed at the main panel. However, as stated above, it is permissable to install one on the line side if it is rated for such use and has an OCPD.

5. A surge arrestor is a different type of device and is installed in a different manner on different parts of the distribution system. A surge arrestor is primarily designed to reduce effects of large surges due to lightning strikes. A TVSS can be designed to handle many other types of anomalies in the power sytem.

 

[steve66]

Re: TVSS

Thanks for all the replies. It is starting to get a little clearer. Now I see the units I am specifing do have a 200KAIC rating. They also have 200KAIC Surge Rated Fuses.

I still am not sure if I can do the #2 tap and feed this device without adding another breaker? Are the fuses in the device enough to protect the tap wire? Couldn't the 600A breaker serve as the disconnect?

STeve

 

[ron]

Re: TVSS

The TVSS requires OCPD either within itself or upstream. Most require a 60A or less of protection.

 

[steve66]

Re: TVSS

Thanks Ron. I specified a breaker for OCP. The device didn't say what the rating of the internal fuses were.

Steve