AEDC Power Control workers stay busy 24/7

Published May 9, 2012
By Philip Lorenz III
AEDC/PA

ARNOLD AIR FORCE BASE, Tenn. -- To say that electrical power at AEDC is a big deal is an understatement.

When Joe Migliaccio, ATA lead test engineer at the Large Rocket Test Facility J6, flipped the switch to fire a CASTOR rocket motor for a well-attended test at AEDC, he had a lot on his mind, including whether there would be power.

"Since rocket testing is short duration - about one or two minutes - the probability of a power loss during that time frame seems small, but then again, with solid rockets we only get one chance to get the data," he said. "You can't fire it twice."

Despite his concerns, Migliaccio is able to focus on the mission because of people like Mark Trybe, one of five power control dispatchers and operators on base who are on the job 24/7, 365 days a year.

They operate the high-voltage electrical distribution system in support of test and base support facilities at AEDC. They also coordinate with TVA to balance the supply of power required for test and support missions and record a power usage based on meter readings or estimate.

Think that sounds mundane or routine? Just ask those at AEDC who depend on a safe and reliable source of power.

"The ability to safely provide a massive amount of electrical power is critical to our unique engine altitude test capability," said Col. Brent Peavy, AEDC's Turbine Engine Ground Test Complex director. "The decision to locate Arnold in middle Tennessee was heavily weighted by the availability of power from TVA.

"It is my understanding that when we bring the ASTF (Aeropropulsion Systems Test Facility) online we are one of the largest 'cities' on TVA's grids, and thus one of the largest cities in the Southeast. The fact that we can achieve this safely every day for 16 hours or more is quite an accomplishment. The power guys have no margin for error."

Tom Wiley, ATA's electrical operations supervisor, said AEDC has two central facility transformers in the main substation and multiple substations for the other major test plants.

"All power for this base comes through the power control main substation here, which the dispatchers control," he said. "It goes to eight major substations which in turn distributes [power] out to all of the facilities at AEDC."

Asked what can go wrong with the power supplied to base, Wiley said, "If we lost an incoming line, most people here at AEDC would not know. Losing all incoming lines is unlikely unless it was some kind of major thing, then we're looking at maybe 30 minutes [before] getting people back online.

"There are five dispatchers and five operators, they work 24/7," Wiley said. "We have one dispatcher on duty per shift, through the second and third shifts. Sometimes we have a spare dispatcher which we call a relief who takes care of the outage work, the writing of the switching orders and the hold orders, where we do configuration control for safe maintenance.

"The dispatcher is responsible for the power coming into the base, the distribution, the load control on the feeder circuits, anything that comes up during his shift - switching, outages, anybody entering a substation, any work that's going to go on a high voltage piece of equipment - they have to come through this dispatcher."

To maintain safety, the dispatchers are the only ones who control power on base.

"We lock all of our systems that we have to keep online," Wiley explained. "We lock them in a configuration where we're the only ones who can change those. On a facility this size, we cannot allow for somebody to just arbitrarily open this one here and do it this way. That would cause a lot of havoc on this base."

Wiley added, "These folks are dedicated to what they do. And they have a good understanding of what the priority is here, safety being number one, mission being number two, safeguarding of the equipment and in general just taking care of business."

Mark Trybe, an ATA dispatcher at Power Control, is a 30-year journeyman electrician with a background in high voltage and protective relaying. He worked at NASA's Langley Research Center, Va., before joining AEDC's workforce six years ago.

Trybe said vigilance is the only way to keep on top of the situation regarding power distribution on base. He said if there is a lightning strike at a substation, the response is routine at first, but could soon get complicated.

"We would get alarms, but we would have an operator go out and visually inspect and give us a report over the radio of what he sees at the scene," Trybe said. "If there is equipment on fire or damaged, we would probably have a main breaker trip, so we would know something happened, but the operator is our eyes and ears."

Whatever the size and severity of an event, whether it is an accident, severe weather or terror event, Trybe said the dispatchers and operators are prepared to act quickly and safely.

"If you had ASTF, PWT (Propulsion Wind Tunnel Facility) and ETF (Engine Test Facility) - if you had all the big boys going, you want to stay attentive to what their load is, because we don't want to charge them for a load they're not using," he said. "Every 30 minutes we'd take a contact with everybody in the control rooms, calling us as they're coming off and on, because we have to contact TVA and let TVA know. TVA has to match generation to AEDC use.

"The worst thing we want to do is have ASTF come up 150 megawatts and then TVA, let's say in the middle of the summer, and they're in a really heavy load condition. We don't want to have TVA get penalties due to generation and use imbalance. We want to keep the test cells attentive to do what Power Control is coordinating with TVA and the same thing coming down; we don't want to suddenly drop a big load."

Max Andolsek, a Power Control operator who has been at AEDC for 21 years, said people in his position must have a strong background in electrical operations with an emphasis on high-voltage electricity.

"[We] perform equipment checks on electrical equipment, high voltage switching configurations, repair de-energized circuits and monitor circuit power demands," he said. "I [also] ensure that voltage is discharged for maintenance in a safe way, with double and triple checking, to ensure lock-out tag-out procedures are being performed as required.

"You have to work well with your dispatcher on proper high voltage switching configuration to protect Air Force resources and personnel."

For Mark Smith, ATA project manager at AEDC's high-enthalpy arc-heated facilities, electrical power is the life blood of testing.

"We receive excellent support from the power control group, and we really appreciate their expertise," he said. "It is absolutely 'mission-essential' for us.

"The power supply is an essential component of all arc jet tests at AEDC. Since the arcs use large amounts of power, the power feed must be coordinated with TVA through the Power Control group. In addition, Power Control also ensures that there are no inherent conflicts in HTL (High Temperature Laboratory) power usage with other facilities, such as the adjacent PWT wind tunnels, primarily 16T and 4T."

Smith doesn't like to think about a power surge or an outage.

"In the AEDC arc jets, large amounts - up to 70 megawatts - of electrical power are converted to thermal energy in the arc heater," he said. "This in turn provides the necessary aerothermal test conditions for our customers."

He said power input to the arc heater is carefully monitored by the facility instrumentation and computers throughout each run. Any deviation in arc current or voltage outside of the preset limits will result in immediate termination of the run.

Smith added, "If this happens, it will often result in data loss to a customer test article if the test article is under test at the time of the shutdown. Since these are typically expensive test articles, such a data loss would be significant to any test program."

The bottom line is the test customers have good reason to trust that they will have power delivered reliably, efficiently and safely whenever needed, 365 days a year, 24/7.