Polyphaser telco punch block surge arrestors

nmfire10 · Post by **nmfire10** » Mon Jun 13, 2005 6:30 pm

We have these little polyphaser surge arrestors on our telco punchdown blocks. They are the littel red thingie with bridge clips attached and a terminal that goes to a ground bus next to the block. I don't have one in front of me to read a model number, but I'm sure they are rather common. We have them on our radio RTPA circuits and our POTS circuits since they all come in right there.

Over the last few years, I've have two of them go bad on me. The result is the things send ring voltage to ground. This is a major PITA because obviously the phones won't ring. This happened once 2 years ago and I went out of my damn mind trying to figure it out. Finally myself and a tech from SBC were walking around baffled and we found it. It happened again last week. It had been so long, I forgot about the thing and once again went bonkers trying to find the problem. I remember eventually, but it was still a pain in the ass.

Is this common or should I not be using these on POTS lines??

tvsjr · Post by **tvsjr** » Mon Jun 13, 2005 9:09 pm

I don't know about their telco protection devices, but their coax surge arrestors have a limited service life. Maybe the telco devices are the same and you're reaching that limit?

nmfire10 · Post by **nmfire10** » Tue Jun 14, 2005 4:20 am

They can't be more than 4 years old.

k2hz · Post by **k2hz** » Tue Jun 14, 2005 4:35 am

It is normal for any type of terminal surge protector to "go bad" after it has taken some surge hits and provided its intended protection. The ground from the shorted protector will either cause a hum from unbalance or false ring trip as you have experienced.

This is how you know that the protector has done it's job and you replace it, being glad that you are not replacing a fried console or base station line interface card instead.

I don't know why the SBC tech should have been "baffled" because the protector is the first thing to check with that type of problem.

Jim202 · Post by **Jim202** » Tue Jun 14, 2005 5:05 am

As was said by others, be gratefull that the Polyphasers did short. They did their duty. Change them out and be thankfull.

You might also get the SBC tech to chage out his protectors on the cable coming into your facility. It has been a number of years since I have had to fight the telco side of the fence.

Go look at the main cable as it comes into the building. There should be a long probably gray block with a bunch of what looks like hex head nuts on the surface. These are the protectors the telco uses on their cable. They are probably all have red colored paint on the hex head of the nut. These should get changed to white. Unles I have my colors backwards. Anyway, the other color changes the protection from a carbon block protector to a gas tube protector.

The gas tube type protector works far better than the old carbon block protectors. The telco tech should have the new style protectors in his service truck. Bend his arm, buy him a donut or what ever it takes. Just get him to change out the protectors on your important circuits.

Jim

nmfire10 · Post by **nmfire10** » Tue Jun 14, 2005 6:13 am

OK. I wasn't aware this is a symptom of it having "done it's job" so I guess this is a good thing. I'll have to find a place to get a few more and replace them.

I don't recall seeing any protection blocks like that though. There is a cross-box there, perhaps it's in that.

kcbooboo · Post by **kcbooboo** » Tue Jun 14, 2005 8:42 am

You need to find the first cabinet that the SBC cable goes into on your property. It could be in a basement or even in a closet. There might even be some lead-cased splice enclosures nearby. All the individual pairs will run from here to the rest of the phone system in the building.

On residential service, this is usually mounted to the side of the house and should have a good ground wire running from it.

Bob M.

JohnWayne · Post by **JohnWayne** » Tue Jun 14, 2005 9:49 am

This is a shot in the dark, but here's something else to look at.

There are basically two types of the protectors: ones for digital circuits (like on a PBX or ISDN), and ones for analog circuits (like POTS). The operating voltage on the digital variety is designed for 48VDC lines, while the analog are designed for ring voltages up to 150VACish. If I remember correctly, the specs on the digital are like +/-80V, and the analog are like +/-200V.

If you have a digital protector designed for 80V MAX, and you send 150V down the line, then it isn't going to last a long time.

I vaguely remember the analog ones being red and the digital ones being black, but that was a few years ago when I was doing telecom for a living. Check yours out and see if they are the correct type.

Jeff

Jim202 · Post by **Jim202** » Tue Jun 14, 2005 5:36 pm

It must have late or thinking about something else on my last post. When i was talking about the telco surge protectors on a long gray block, this is the old style you will probably find on lead cable.

The new style termination "DEMARK" points are a light green box with covers. The protectors are of the long black plug in style about 2 inches long. They are about 3/4 inch square. They have like 5 or 6 pins on the end of them. The little grab handle is on the other end. You may see some of them red in color.

Talk with the telco service man and have him explain what the different styles that are available. The the poster before me said there is data voltages and there is regular POTS line voltages that need to withstand the ringing voltage.

Jim

nmfire10 · Post by **nmfire10** » Mon Jun 20, 2005 10:53 am

Well, this explains a lot. The existing and toasted ones are the MPT-75 model, which is the 75vdc operating voltage. I'm going to order a bunch of MPT-200 models which is the 200vdc operating voltage.

http://www.polyphaser.com/kommerce_prod ... IS-MPT-200

Jim202 · Post by **Jim202** » Mon Jun 20, 2005 1:52 pm

Be careful on the type of protectors your going to order. Make sure they match the type of service they are going into. Don't use the 200 volt type for data circuits or radio remote tone control circuits. They won't clamp the surges low enough.

Don't use the 75 volt units on regular telephone circuits. They won't allow the normal ringing voltage to ring the bell circuits on the phones.

If you happen to have a PBX, check what votage are being used. If you have a T1 data circuit for the PBX, it probably already has some surge protection at the data packs supplied by the phone company.

Jim

[quote="nmfire10"]Well, this explains a lot. The existing and toasted ones are the MPT-75 model, which is the 75vdc operating voltage. I'm going to order a bunch of MPT-200 models which is the 200vdc operating voltage.

http://www.polyphaser.com/kommerce_prod ... IS-MPT-200[/quote]

nmfire10 · Post by **nmfire10** » Mon Jun 20, 2005 4:25 pm

All the RTPA circuits have MPT-75's on them already and I'm not planning on changing them for that very reason. It's the POTS lines (3) that need the MPT-200's. I'm just going to order a bunch of each so I have some spares.

There are a total of (3) POTS lines and (3) RTPA lines. These are the only lines that *I* have equipment on and they do/will all have these things. Our PBX and all our data stuff is on the protected side of those lines.

The co-located //\\//\\ Police equipment (FDPA & Quantar) has nothing, but I don't make their decisions, as is obvious from the mess. I'm thinking it might not be a bad idea to advise them it is now a *requirement* in the building since I don't want their unprotected equipment blowing up my fire stuff due to close proximity. Hmm, if their stuff blows up because they didn't want to listen to me and my stuff stays on the air, that would make a great "I told ya so" opportunity!

Jim202 · Post by **Jim202** » Mon Jun 20, 2005 8:07 pm

You need to also look at the total grounding system when it comes to surge protection. Just the protectors on the telco lines by itself is not enough. You need to make sure you have a good ground system.

You notice I didn't say ground, but ground system. This includes a ground ring outside under the ground. There should be ground rods spaced about every 16 feet if your using 8 foot ground rods. There will not be any sharp bends in the ground ring. All ground connections will be "exothermically welded" to the ground wire and ground rods. The wire should be at a minimum of # 2 AWG, solid, tinned copper.

You should have a master ground bar inside the equipment shelter near where the coax cables, power and telco all come in. The telco should be grounded to this master ground bar. There should be a surge protector on the AC power that gets grounded to this master ground bar. Every radio rack and cable tray gets grounded to this master ground bar.

The outside ground ring should also have a ring around the tower. Each leg of the tower will be connected to this ground ring. The tower ground ring and the shelter ground ring will be tied together in at least 2 places. Both rings should be 24 to 30 inches below the surface. If you have a frost line in your area, then the ground ring will be below the frost line.

What this grounding system is called is a "Telecommunications Grounding System". If you talk to Motorola, they call it the "R56" grounding standard. Call it anything you want, no one part of it will do the job by itself. It takes the whole system to protect your communications system.

There are more details to the grounding system, but what I have talked about here covers most of the main points.

Jim

nmfire10 · Post by **nmfire10** » Mon Jun 20, 2005 8:11 pm

The entire site is exactly as you describe. This is all in one of those little pre-fab radio huts. The whole grounding system is there. The 66 block is the only part that is in need of attention right now.