Meltdown

After one of our clients had an FM station go off the air over the weekend, I investigated and found this:

Transformer melt down
Transformer melt down

Looks like something one might find in the reactor room at Chernobyl or Fukushima.

Transformer melted down
Transformer melted down

This is at one of those sites with three phase open delta power.  Needless to say, the transformer is toast, perhaps the entire transmitter too.  This will be another fun transmitter scrapping project.  I was thinking about this; over the last five years, I have scrapped at least ten to fifteen old tube transmitters.  The old tube types are going away fast, as are those that can still work on them.

Good only in Europe

And some parts of Asia:

Equipment rack outlet with 220 Volts to ground.
Equipment rack outlet with 220 Volts to ground.

It seems the power company has some work to do. The other leg measures 28 volts to ground, which to me means the Neutral has been lost somewhere. Fortunately, the transmitter was running on 240, which looks normal on the voltmeter. Everything in the rack; the remote control, exciter, STL, etc has been damaged or destroyed.

Then of course, there is this:

Utility line
Utility line

That is the power and phone line in those trees, as it leaves the road and travels approximately 1,700 feet through the woods.  It is a private line and the utility will not do any work until the trees are cleared away.  In all fairness to the current owners, who have owned the station for not quite a year, this situation has been like this for a long time.

The rotary phase maker

I alluded to this in an earlier post: Open Delta three phase service.  Some transmitter sites are fairly remote and three phase power is not available.  Occasionally, with lower powered radio stations, this is acceptable because those transmitters can be configured to run on single phase power.  However, almost any transmitter above five kilowatts or so will require three phase power.  This is the case at the WQBJ transmitter site in Palatine Bridge, NY.  The site is located in the middle of farm land and only has single phase service.  The nearest three phase service is several miles away and the utility company wants several hundred thousand dollars to upgrade the line.

WQBJ transmitter site electrical service
WQBJ transmitter site electrical service

The station is a class B FM with a six bay full wave spaced antenna.  Even so, the TPO is 17 KW, which makes some type of three phase service a requirement.

WQBJ six bay Shively 6810 antenna
WQBJ six bay Shively 6810 antenna

The main transmitter is a Broadcast Electronics FM30B, which is now 25 years old.

WQBJ main transmitter, Broadcast Electronics FM30B
WQBJ main transmitter, Broadcast Electronics FM30B

The backup transmitter is a CSI FM20T, which is almost forty years old.

WQBJ backup transmitter, CSI FM20T
WQBJ backup transmitter, CSI FM20T

Rather than do an open delta service, which is not desirable for several reasons, both transmitters have their own rotary phase makers.  From a reliability and redundancy standpoint, this is the right way to equip this site.  The rotary phase makers are essentially a motor generator combination which takes the split phase power and generates a third phase.

WQBJ phasemaster, backup three phase converter
WQBJ Phasemaster type T, backup three phase converter
Phasemaster parallel connection diagram
Phasemaster parallel connection diagram

The phasemaster is is a 40 KVA unit and is connected to the backup CSI transmitter

WQBJ Roto Phase, main three phase rotary converter
WQBJ ARCO Roto Phase, main three phase rotary converter

The Roto Phase unit for the main transmitter is actually two 40 KVA units connected in parallel through dry core isolation transformers.  Incidentally, the Roto Phase units need to have their bearings changed every ten years or so.  This requires the units be disconnected, placed up on their end.  To get the old bearing out, the housing has to be cooled with liquid CO2.  Both units are due for new bearings soon, which should be a pleasant job indeed.