Happy New Year!

After a bit of reflection and a few good conversations over the New Year’s Holiday, I decided that I should continue my work on this blog.  I would like to thank all those that have stuck by and waited.  I have received numerous emails and messages off line, all of which have been read and appreciated.

Since the abrupt stoppage last July, which was absolutely necessary for me, many things have happened within the business.  Fortunately, during the hiatus, I was still taking pictures.  After sorting through them, here are a few interesting things that happened:

At one of our client’s AM transmitter sites in Albany, NY a 2.6 Million Watt solar system has been installed.

WROW-AM Steel mounting poles on antenna array field
WROW-AM Steel mounting poles on antenna array field

This project required many steel mounting posts be driven into the ground around the AM towers.  I don’t even know how many, but I would hazard a guess of over three hundred.  Each one of those mounting posts was hand dug down a depth of 6-10 inches to look for ground wires.  Where ever a ground wire was found, it was moved out of the way before the post was set.

WROW-AM ground wire moved out of way
WROW-AM ground wire moved out of way

Basically the solar array covers about 1/2 of the antenna array field.  All of the steel mounting hardware is tied into the ground system, making, what I am sure is a pretty large above ground counterpoise.

WROW-AM solar panel mounting hardware
WROW-AM solar panel mounting hardware

View from the south looking north:

Solar Array installed on WROW antenna array, Glenmont, NY
Solar Array installed on WROW antenna array, Glenmont, NY

View from the north, outside of the transmitter building, looking south:

Solar Array installed on WROW antenna array, Glenmont, NY

Power company interface and disconnect:

Solar Array utility company disconnect, Glenmont, NY
Solar Array utility company disconnect, Glenmont, NY

The utility company had to upgrade the transmission lines to the nearest substation to handle the additional power produced by the solar system. All in all, it was a fun project to watch happen.

At a certain studio building, which is over 150 years old, the roof needed to be replaced.  This required that the 3.2 meter satellite dish and non-penetrating roof mount be moved out of the way while that section of the roof was worked on.

3.2 meter satellite dish

Dish ready to move, all of the concrete ballast removed and taken down from roof.  The roofing contractors constructed a  caddy and the entire dish and mount was slid forward onto the area in front of it.  Since the front part of the roof was not reinforced to hold up the satellite dish, we did not reballast the mount and the XDS receivers ran off of the streaming audio for a couple of days until the dish was put back in its original position.

3.2 meter satellite dish ready to move
3.2 meter satellite dish ready to move

A couple of other studio projects have been underway in various places.  Pictures to follow…

One of our clients sold their radio stations to another one of our clients.

There has also been a bankruptcy of a major radio company here in the good ol’ US of A.  Something that was not unexpected, however, the ramifications of which are still being decided on in various board rooms.  One of the issues as contractors is whether or not we will get paid for our work.  All things considered, it could be much worse.

Learned a valuable lesson about mice chewed wires on generator battery chargers.  I noticed that the battery charger seemed to be dead, therefore, I reached down to make sure the AC plug was in all the way.  A loud pop and flash followed and this was the result:

Arc burns, right hand
Arc burns, right hand

My hand felt a bit warm for a while.  The fourth digit suffered some minor burns.  There is at least one guy I know that would be threatening a lawsuit right now.  Me, not so much…  All of the high voltage stuff we work on; power supplies that can go to 25 KV, and a simple 120 VAC plug is the thing that gets me.

The return of the rotary phase maker.

Rotary phase maker, Kay Industies T-10000-A

Mechanically derived 3rd phase used when the old tube type transmitter cannot be converted to single phase service.

Those are just a few of the things I have been working on.  I will generate some posts on current projects underway.  Those projects include a 2 KW FM transmitter installation, another studio project, repair work on a Harris Z16HD transmitter, etc

It is good to be back!

Out with the old, in with the new

Pictures of a backup power systems replacement evolution at one of our clients.  The old generator was a Katolight 45FGH4, circa 1990.  The new generator is a Cummins Power GGHE-1503557 60 KW 3 phase.  Unfortunately, when the Katolight generator was moved from the previous studio location in 1998, it was never installed correctly.  The 500 gallon propane tank was undersized, the gas tubing was undersized, etc.  We fixed those items, but the damage was done.  After running too lean under load a few times, the head gasket blew and there is oil in the antifreeze and antifreeze in the oil.  It is a Ford straight six engine, and sure, we could rebuild it, but why bother.  This is a major group of stations in a very lucrative market, it makes much more sense to replace the entire unit.

Katolight Genset hooked up to the crane, ready to move
Katolight Genset hooked up to the crane, ready to move
Generator lift
Generator lift

In addition to the head gasket problem, the load on the generator has increased. Since the old generator was installed in 1998, two more stations have been added to this facility. That means another air studio, another production studio, more computers, servers, air conditioning etc. Thus, the new generator is rated for 60 KW.

Cummins Power Generator delivery
Cummins Power Generator delivery
Cummins generator lift
Cummins generator lift

After the GENSET is placed, connections for remote start, battery charger, block heater and AC power output are made. We were able to reuse the existing conduit and cable, thankfully the electricians used 3/0 AWG cable for the AC power connections to the transfer switch.

Cummins Power generator in place
Cummins Power generator in place

It appears that they have dropped the Onan name, but not the color, completely.

Generators and mice

Never a good mix, unfortunately, it usually turns out bad for the mice and sometimes the equipment.  This is a Onan GGMA 20 KW propane generator installed in a rural area, not that the location matters that much.  Mice will find what they perceive as a safe secure spot to hold up for the winter.

Onan GGMA20 propane generator
Onan GGMA20 propane generator

Unfortunately, the mice decided that the generator cooling fan was a good place to make a nest.  It probably was until the generator started, then the mice had a quick lesson in centripetal force.

Mice and generator
Mice and generator

This will require some additional maintenance in the spring time when I change to oil.  By that time, the carcases should be mostly dried out and easier to deal with.

Onan generator mice
Onan generator mice

The mice are generally a nuisance, getting into ATU’s, transmitters, electrical panels, spare parts boxes, etc.  Once in place, they begin to bread and reproduce.  The gestational period for a mouse is 21 days, which means populations rapidly increase creating further problems. If left alone, mice will chew through electrical insulation, control wires, cardboard boxes, packing material and so on.  They tend to carry diseases like hantavirus and bubonic plague.

I don’t usually agree to using poison to get rid of pests, it tends to linger in the environment and accumulate up the food chain.  However, judicious use of some type of poison is usually the only way to effectively get rid of a mouse infestation.

Wherever possible, make sure that all openings and holes into equipment and buildings are sealed up.  Do not kill snakes and other predators, who will assist in keeping the mice in check.  Employ traps and wear gloves when removing dead mice and mouse parts.  Beware of fleas.

The Generator and the UPS

An issue I had to deal with recently; an unstable generator/UPS relationship.  When the generator was running under load, it surged repeatedly causing the UPS to drop out and not recharge.  Eventually, the UPS ran out of juice and shut down, killing the power to the Sine Systems remote control and telephone system.  Of the two, the remote control was the biggest pain to fix, as it lost it’s timed commands and would not reduce power at sun set for the associated class D AM station.

What went wrong?  This is a chart of typical problems with generators operating UPS loads:

Symptom Potential Problem
Fail to “lock on” to generator power Improper generator frequency or voltage
Poor generator regulation
Unrealistic performance requirements
Instability of generator Voltage regulator sensitivity
Control loop compatibility
Filter/control interaction
Governor or AVR problem
Fail to sync bypass Frequency or voltage out of range
Poor frequency stability
Unrealistic performance requirements
Changes to total load on the system
Generator output voltage distortion
Instability at specific load levels Control loop compatibility
Instability at load changes Control loop compatibility
Metring errors Generator output voltage distortion
Loss of voltage control Excess capacitance in filters vs. load

Table courtesy of Cummins Power Generation.

Generator excitation methods can be the culprit in many of these situations.  Generators often use one of three types of excitation for their field coils:

  • Shunt excited SCR (silicon controlled recifier)
  • Shunt excited PWM (pulse width modulation)
  • PGM (permanent magnet generator)

Of the three, permanent magnet generator is the most stable since the AVR (automatic voltage regulator) is powered by a separate small generator which is unaffected by the load on the main generator output.  SCR and PWM both use the generator output windings, which makes them susceptible to load inducted voltage distortion brought on by non-linear loads.  Therefore, in locations where large UPSs are known to be part of the load, PGM excited generators are the best choice.

PMG generator diagram
PMG generator diagram

Sometimes, the generator is already in use before the UPS is installed.  In that case, there are some remedial steps that can be taken.  The speed which the voltage regulator reacts to changes in the load is often the culprit in many of these situations.  It may seem counter intuitive, however, the faster the AVR reacts, the more fluctuations there will be in the voltage and frequency.  A UPS can operate under a wide range of voltages and frequency, provided they do not rapidly change.

Depending on other loads, it may be necessary to dampen the gain on the AVR to slow it’s reactions down.  This will work if there are not large intermittent starting loads on the generator such as air conditioning compressors.

Another method would be to delay the UPS transfer to generator power until after all the other loads have been satisfied.  This will ensure that the generator voltage and current fluctuations are damped by the existing load.

The generator’s size needs to account for the equipment attached to the UPS and the battery charging load. With a larger UPS, the battery charging load can be significant. Generators that are improperly sized will not be made to work under any circumstances, hence the “unrealistic performance requirements” noted in the chart above.

You can read the entire Cummins Power white paper on generators powering UPS loads here.