The Isolated Ground

We get requests to install Isolated Ground outlets from time to time, especially with sensitive equipment. TELCO likes to have isolated grounds on their fiber MUX’s.  It can become an issue with branch circuits in split-phase or three-phase services that share the same ground and neutral conductor.  This can lead to a ground loop between neutral and ground, which will create all sorts of havoc in a broadcast facility.

20 amp, 120 volt Isolated Ground Outlet
20 amp, 120 volt, Isolated Ground Outlet

The National Electrical Code covers Isolated Grounds (IG) and sensitive equipment in several sections.  The first is section 250.146(D), which states that the installation of isolated ground receptacles is permitted.   The grounding conductor connected to such receptacles is permitted to pass through one or more panel boards, boxes, conduit bodies, etc without being bonded to them.  However, said panel boards, metallic boxes, conduit bodies, raceway, etc must also be grounded separately.  That means running two ground conductors, usually, the isolated ground conductor is green with a yellow stripe or spiral.

Studio electrical diagram isolated ground
Studio electrical diagram isolated ground

The second is section 640.9(A), which refers to separately derived power systems.  This section deals specifically with balanced power; 60 volts AC to ground.  In such cases, a separate ground conductor is allowed as outlined in section 250.146(D) and in 647.6(B), which states that the grounding buss should be connected to the grounded conductor on the line side of the separately derived systems disconnecting means.

Other sections of the NEC that may apply to broadcast radio and television facilities:

  • Article 455, Phase converters (rotary phase converters)
  • Article 480, Storage batteries (UPS)
  • Article 520, Theaters, Audience Areas of Motion picture and Television studios, Performance areas, and similar locations
  • Article 640, Audio signal processing, Amplification and Reproduction Equipment (Audio wiring)
  • Article 645, Information Technology Equipment (computer equipment and network wiring)
  • Article 647, Sensitive Electronics Equipment (balanced power 60 volts to ground)
  • Article 702, Optional Standby systems (generators)
  • Article 770, Fiber optic cables
  • Article 810, Radio and Television Equipment (antennas, towers, and grounding)
  • Article 820, Cable TV (CATV)
  • Article 830, Network-powered broadband communications systems (power over ethernet)

If interested, I can do articles on these sections as well.

Windows XP

WDST technical operation center
technical operation center

It is time to plan and upgrade those machines running Windows XP. After April 8, 2014, Microsoft will no longer be updating the software and/or patching security holes. Many in the IT industry believe that after that date, hackers will attempt to break the popular operating system which has been in use for twelve years.

Approximately one-third of all Windows operating systems in use today are XP.  Microsoft has already warned users that potential hackers could use security patches and updates for Windows 7/8 systems to scout for vulnerabilities in XP.  I know several radio clients have automation systems and office networks that run primarily Windows XP.  Microsoft may be overstating the risks of remaining on XP, then again, they may not be. This situation has been described in several trade magazines as “A ticking time bomb,” or equally dire:  “Microsoft urges customers up upgrade or face ruin.”

In radio station infrastructure, very few systems are as vital as the audio storage and automation system.  Without a functioning automation system, most stations would be dead in the water.  If an automation system were to hack and be ruined completely, I do not think there are enough people left on most stations’ payrolls to run an operation manually, even for a short period of time.   I, for one, do not want my phone to start ringing on April 9th with a bunch of panicky managers talking about how unacceptable the situation is.

Failed High Voltage Contactor

This contactor was used to replace the Furnas contactor installed as original equipment when the transmitter was manufactured in 1986.  Furnas is no longer in business, thus the ABB A145-30 was substituted. It was purchased directly from Broadcast Electronics for an FM35A transmitter:

ABB A145-30 contactor
ABB A145-30 contactor

It was installed about 18 months ago and has been in nearly continuous use since.  The broken white plastic housing surrounds the contactor coil and is responsible for pushing and holding down the contact fingers.

ABB A145-30 contactor coil cover
ABB A145-30 contactor coil cover

Looks like the coil is running too hot and damaging the plastic. This resulted in a failure of the contactor to make and no high voltage to the transmitter PA.  Obviously a problem.  I spoke to BE about this and they did not have a good answer.  Actually, what they said was “That contactor is rated for 220 amps,” which is true enough. The only thing that I can think of is the coil is rated for 208 volts and the transmitter is connected to a 240-volt delta service.

A new contactor was ordered and installed yesterday.

I will investigate the coil voltages further, but for now, the 27-year-old transmitter remains on the air.

Broadcast Electronics FM35A
Broadcast Electronics FM35A

New Broadcast Engineer

The new engineer
The new engineer (banana for scale)

Update and bump: The many great comments about the SBE certifications got me thinking about what a Broadcast Engineer actually does. I remember typing something about it quite some time ago, thus, I dredged up this old post originally from August 8, 2009 out of the archive.

Enjoy:

The other day, the NTR (Non-Traditional Revenue) person came to me and said “Great news!  We hired a new web guy, he knows all about engineering too!”

Really?

So I spoke to the new Web Master/Broadcast Engineer for a bit.  As it turns out, he knows how to do things like reboot the XDS satellite receiver, and reboot an Audiovault server, he has been to a transmitter site a few times to take meter readings.  I suppose these days, that is what counts as being a broadcast engineer.  Someone with this level of experience could get by for a bit until something really bad happened.

Sadly, I think (my former employer) upper management and ownership believe that this guy could do my (old) job.  To them, I am an employee number, with a salary and benefits package worth X.  If they can replace me with someone that makes <X, that would represent savings.  Plug that guy into this spot, everything will go on as it did before.

I don’t think they understand exactly what a Broadcast Engineer does.  On any given day, I may:

  • Program an automated computer
  • Change the battery on a backup generator
  • Change the battery bank in an 18 KVA UPS
  • Clean a transmitter
  • Aim a satellite dish
  • Troubleshoot a DS-1 Circuit
  • Troubleshoot a T-1 MUX
  • Repair a microwave transmitter or receiver
  • Take a set of monitor points
  • Repair a tower light flasher circuit
  • Install a console (analog, digital, IP routing, TDM routing)
  • Repair a CD player
  • Troubleshoot a transmitter RF module
  • PM a generator
  • Work with a tower crew to place an antenna on a tower
  • Install an RF connector on 3-inch transmission line
  • Wire an air conditioning unit at a transmitter site
  • Repair lightning-damaged ATU
  • Troubleshoot an AC unit
  • Aim an STL antenna
  • Repair an RPU transmitter
  • Design a computer network
  • Troubleshoot and repair an FM transmitter
  • Wire a new rack room
  • Coordinate a complex format change
  • Install a translator
  • Program and wire a new satellite receiver
  • Wire a transmitter remote control
  • Hike to a transmitter site after a natural disaster
  • Troubleshoot an audio hum
  • Pass an FCC inspection
  • Install and program an EAS unit
  • Wire a new studio
  • Design a tower light monitor circuit
  • Fix a studio phone system
  • Install an audio router
  • Match an AM transmitter to a new tower
  • Wire an ethernet patch panel
  • Program a wireless access point
  • Install an IP router
  • Manage a new tower project
  • Install a new transmitter
  • Re-install an old transmitter
  • Make NRSC measurements on an AM transmitter
  • Repair a corrupt OS
  • Replace a hard drive
  • Reboot a server
  • Fix a reel-to-reel machine
  • Install a computer program
  • Clean a console
  • Pass an inspection by the fire marshal

To name a few.  In other words, there are a lot of complex systems at a multi-station radio facility.  Some of this can be learned at various schools and colleges.  A lot of it is experience.  There is no substitute for an experienced veteran broadcaster who has seen almost everything and can think on his or her feet.

I have had this discussion with the market manager, and he gets it.  I know that he understands and knows more about the ins and outs of all of our studio and transmitter sites.  Things like, where is the water shutoff, the handle is broken off of the toilet on the second floor.  Of course, I know it is downstairs in the furnace room next to the fire sprinkler system.

I know where the skeletons are buried.  I have the inside numbers for the utility companies and the phone company.  I know the code enforcement officer for most of the municipalities where we own buildings and property.

Yet, the only thing they see is X.