Energy Savings

Behind-the-scenes savings: voltage regulator maintenance

PEC program you've never heard of is putting money back in your pocket

Unless you’re a chemist or technician, there’s a good chance you’ve never heard of dissolved gas analysis.

Three voltage regulators on a platform beneath electric poles and lines.
Voltage regulators outside Johnson City. These hardworking pieces of equipment operate 24 hours a day to maintain the voltage that powers your home or business.

But as part of our innovative voltage regulator program introduced in May 2016, this specialized process has increased reliability and potentially prevented outages to PEC members, not to mention time in the dark. And the savings only grow from there.

“It’s a very good cost-saving tool,” explained PEC Technical Services Manager Bryan Harbuck. “With this program, we catch the problem before it occurs.”

Our system utilizes about 420 voltage regulators: transformers that have the ability to raise or lower voltage in response to demand. When everyone gets home from work in the summer at 5 p.m. and turns on their air conditioner, voltage regulators make sure the right amount of electricity flows out to the lines without a service interruption. They’re vital, hard-working pieces of equipment, running 24 hours a day. They’re also expensive: each can cost the cooperative $5,000 to $30,000 when an issue occurs.

In the past, we relied on a time-based maintenance program to care for our regulators: each piece of equipment got pulled and replaced on a five-year cycle, regardless of its condition.

“There’s just no visual way to see what’s going on inside a regulator,” Harbuck said. “You cannot tell what’s going on from the outside.”

A new age

Our new voltage maintenance program, which combines visual and operating inspections with dissolved gas analysis, allows our crews to get a precise peek into the internal status of a regulator. Chemical analysis of a sample of the cooling oil within each individual piece of equipment can help determine its actual lifespan, and it’s translating into savings for our members.

“Instead of changing out a perfectly good piece of equipment every five years, we can use it for the full seven, eight, 10 years, making only minor fixes,” explained PEC Equipment Maintenance Supervisor Eric Bitzko. “We’re getting a better usage over the course of its lifespan.”

In addition to extending the lifespan of some equipment, the program has caught others right before critical breakdown. Since our technical services team started the program, Bitzko said, “I know we’ve caught 20 to 30 of them that were close to completely failing.”

None of those regulators were scheduled to be replaced this year. Without the program in place, crews would not have known to intervene before the equipment broke down: meaning that 20-30 outages, potentially affecting hundreds of members, have been prevented this year alone.

Three photos of a PEC lineworker testing a voltage regulator.
PEC Technical Services Manager Bryan Harbuck, center image, takes a sample of insulating oil from a voltage regulator. In the past, regulators had to be de-energized and physically removed every five years for a rebuild — a process that required substantial staff time. Now, we can take test samples of the cooling oil in a matter of minutes without removing the equipment from service. Harbuck will send this sample, right, to a lab, where analysts will burn the oil and analyze the gases released in the process. The gas levels provide a sneak peek into the equipment’s internal status.

DGA: the scientific approach

Dissolved gas analysis is a deceptively simple procedure, belying some exceedingly complex chemical reactions. Crews take a sample of the oil from a regulator and send the sample to the lab. It’s then run through a gas chromatograph: basically, the oil is burned and the gases released in the process tell analysts about the state of the equipment.

“The ratio of those gas levels to each other tells us what’s going on in the regulator,” Bitzko said.

For example, acetylene is created only at temperatures of 700 Celsius or higher. So if there’s a high ratio of acetylene to other gases in the oil sample, that’s a sign that something inside the regulator is getting very, very hot: an indicator that the regulator needs to be replaced, stat, to prevent outages.

Other gases, like ethylene, ethane, carbon monoxide and carbon dioxide, are produced at lower levels of heat. Their presence can indicate minor damage or friction within the machines, signaling that the regulators are operating inefficiently. That inefficiency gets ultimately transferred to line losses: electricity wasted before it gets used, a cost that is absorbed by PEC and its members.

In this way, decrypting the complex code of gases lets us see when equipment needs to be repaired and adjusted for peak efficiency. This generates savings we pass on to you.

Money in your pocket

“The biggest thing is, by doing this, we’re going to be more efficient at regulating voltage throughout our system, and that’s going to translate into cost savings for the membership,” Bitzko said. “Because we can be more efficient with our power delivery, we’re going to get cheaper rates, we’re going to be able to drop our overhead down, and we’re going to be able to transfer those savings back to the membership.

“I’m a member, too,” Bitzko said, laughing. “So, if I can do things at work that will help lower my bill, then not only does it help me, but it helps everybody else.”

Lower costs and higher reliability: now that’s the cooperative difference.