Your Complete Guide to Maintenance of Substation Equipment
We put an enormous strain on our power grid, and as such, it’s of the utmost importance that it stays in working order at all times. To do that, utility maintenance companies need to ensure the maintenance of substation equipment. In fact, service should ideally only be interrupted when there is scheduled downtime.
Unfortunately, many utility maintenance companies overlook the proper maintenance of substation equipment, doing only the minimum when it comes to inspections and regular cleaning. These are crucial steps to any preventative maintenance program.
When utility maintenance companies fail to keep up with the maintenance of substation equipment, they can wind up facing issues with power distribution and the transmission of it. The results are not just dissatisfied customers, but also expensive repairs and unplanned outages, labor, and overtime that all wind up being more expensive than the resources proactive maintenance would have required.
Why Is Maintenance of Substation Equipment Important?
As mentioned already, utility maintenance companies need to keep up substations to avoid service interruptions and prevent unanticipated costs. However, the importance of the maintenance of substation equipment for utility maintenance companies goes further than that.
Aging Infrastructure
Much of the infrastructure in place across the nation for electricity generation and distribution is not just old — it’s completely outdated. High-voltage insulation gets dirty and wears down, and many transformers still in use date back multiple decades, putting them at serious risk for corrosion. UtilityService.net points out that huge swaths of the national grid are actually more than half-a-century in age. The maintenance techniques for these parts are sometimes just as old.
Back then, there were widespread assumptions that modern steel wouldn't fail due to corrosion. However, this has proven to be demonstrably false. Utility maintenance companies simply can't keep doing the same maintenance of substation equipment that they've been repeating over and over for decades on end.
Pollution Is Taking a Toll
Pollution can take many forms, including:
Acid rain
Ash
Engine exhaust
Smog
Soot
Some of these are byproducts of the industry itself, but they can also come from many other sources. None of that matters, however, when these various forms of pollution float through the atmosphere and then land on insulators. Rain will wash a lot of it away, but the water can also mix with some of it to make things worse. Add in dust and blown soil, and utility maintenance companies can have their hands full keeping up with the maintenance of substation equipment in any part of the country.
Normal Weathering
Even without the impact of pollution, just normal weathering takes its toll on transformers. They sit there exposed to the full force of any and all weather that passes through, including but not limited to the following:
Blown dust abrasion
Precipitation
Thermal cycling
Ultraviolet light
Utility maintenance companies that don't focus enough on the maintenance of substation equipment will see the paint on transformers bear the early brunt of this constant beat-down, only to see the paint fail before transformers and other equipment follow suit internally.
Best Practices for the Maintenance of Substation Equipment
Even with aging and at-risk hardware, installations, and infrastructure, there are still many steps that utility maintenance companies can take towards the maintenance of substation equipment.
Inspection and Cleaning
High-voltage insulators need to be inspected on a routine basis. They are likely to need cleaning just as frequently.
When the surface of any high voltage insulator has any material settling on it, there will inevitably be a reduction in its insulating properties. Modeling and predicting this issue is very complicated, although you can count on two things happening sooner or later without cleaning:
Arcs will form
Or a flashover will happen
Either can result in possible damage to the equipment, service interruptions, and labor costs that utility maintenance companies simply didn't plan on. Consumers won't believe that the maintenance of substation equipment is happening in an orderly fashion if they weren't warned about the power outage first, so spinning this in a positive light might make public relations even worse.
When utility maintenance companies consistently make inspections and clean routine components as part of their maintenance of substation equipment, they can prevent the accumulation of all contaminants. Practices like these also reveal damage from many other sources. These can include manufacturing defects and corona effects.
Repainting Surfaces
In addition to regular inspections and cleaning, painting should be a regular activity. The moment someone notices rust on any transformer, the time has come to schedule a round of transformer painting. When a coating has failed at one spot, it's usually indicative of coatings close to failing on many other surfaces. This is especially true for transformers grouped at a location with similar ages and consistent exposure to wear and tear.
Repainting is an effective means to remove rust. When utility maintenance companies are able to prevent deep corrosion from happening because of their maintenance of substation equipment, they'll make sure their installations last a lot longer.
Good coatings also prevent the intrusion of water and moisture. While moisture-related failures account for a small percent of all transformer failures, the presence of water inside a transformer can shorten dielectric oil lifespan. This reduces efficiency and speeds up your intervals between refurbishments and overhauls.
Utility maintenance companies that do regular rust removal and painting as part of their maintenance of substation equipment will also keep their systems cooler. Rust is a known thermal insulator that impacts operating temperatures and pump loads. Cooling fins and pipes in the cooling systems will also suffer fewer leaks. This is actually a very common failure mode for transformer cooling systems.
Responding to Corrosion Penetration
Any structure or equipment made using steel has to be analyzed all the time for corrosion. Load-bearing structures of substantial size, including pylons and line supports, are especially susceptible to mechanical failure thanks to corrosion. These structures face dynamic loads where weather constantly shifts the loads across the whole structure. This lets rust penetrate deeper and faster into the components, much like what happens with bridges.
Instrumentation transformers also suffer greatly from penetrating corrosion. Moisture contamination even through the smallest of leaks can result in:
Rust
Thermal failure
Service outages
Local circuit damage
Adjacent circuit damage
Primary and Secondary Testing
SMC advocates for testing, both primary and secondary. Let’s break down these two different categories.
Primary Testing
Utility maintenance companies should consider the cost and failure effect of circuit breakers and power transformers. Many older versions are still in use, and their aging requires routine maintenance.
Circuit breaker testing is a best practice in the maintenance of substation equipment. Routine analysis of both electrical and physical parameters can help utility maintenance companies predict abnormal operations in advance. Check these parameters frequently:
Coil conditions
Contact resistance
DC battery status
Motion analysis
Open/close timing
Poles synchronism
In addition to testing individual components, make sure that the entire protection circuit is tested periodically, especially following any modifications to the system. The overall circuit integrity must be maintained at all times.
Secondary Testing
Secondary testing is necessary to make sure a protection scheme still offers sufficient performance even years after the initial installation. Secondary injection tests should be conducted at appropriate intervals in order to check wiring, protection panels, and relays for satisfactory performance levels.
Secure the Perimeter
The experts at Substation Safety are big believers in minimizing potential threats from outside the substation environment. Unwanted visitors and traffic, be it human or animal, can result in damage and deterioration to the installation.
A robust security program should include the following:
Fencing: Whether metallic or otherwise, perimeter fencing reduces stray animals, children, scaling, and trespassing. In many part of the country, such fencing has to be at least 7 feet in height with barbed wire permissible.
Avoiding Visitors: Visitation might not be something you can totally prevent, but when necessary, they need to be accompanied by industry personnel and only using PPE and the appropriate safety precautions.
Preventing Equipment Storage: It's tempting to store equipment at substations. They also get used as material depots at times. However, this leads to multiple potential risks. For starters, it reduces free space for technicians. Second, it can make a substation an alluring target for material thieves, especially if they're already on the hunt for pricey electrical components. Third, substation technicians might not know the dangers of any foreign equipment, materials, or supplies stored in a substation.
Regulating Vehicle Traffic: Vehicles need to be monitored at the least. At best, they should be guided. Drivers should have clearance to enter the facility, and vehicles need physical clearance from any substation components that might be hanging overhead.
Secure Battery Stores: Rooms for battery storage have many chemical hazards. Secure them to the point of only authorized access.
Things Utility Maintenance Companies Should Avoid
While there are a great many best practices that utility maintenance companies should follow, there are also things that they should avoid. Here, we’ll detail a few of the most common pitfalls when it comes to the maintenance of substation equipment.
Employee Complacency
EC&M warns against substation technicians getting lazy or sloppy. Anyone just going through the motions of their assigned duty shifts and responsibilities might be risking injury to themselves and others. If human lives are at risk, then the equipment in a substation is certainly at risk as well.
Neglecting Battery Maintenance
Batteries can be the necessary backup power when blackouts happen, but they may not take care of anyone when the power is out if they weren't cared for when the power was on. Corrosion and deterioration must be monitored at all times through visual inspections, qualification tests, and performance measurements. Batteries require proper ventilation and storage temperature. Many utility maintenance companies keep their batteries at a consistent 77 degrees, knowing that battery life goes down with any temperature increase past that.
Ignoring Manufacturer Specifications
When testing individual components, don't just test for assumed standards. Also test compared to manufacturer specifications. This is particularly true for voltage. Make any and all adjustments necessary to stay in alignment with manufacturer standards. This can seem like a pain if those standards are actually more stringent or in excess of normal standards, but staying as close to them as possible makes the equipment run better and longer.
Ignoring One-Line Diagrams
At some point, every technician in a substation will rely on these configuration diagrams to learn the layout of substation components. They should be able to see both normal and also abnormal conditions in a glance, knowing which parts require isolation and grounding. Diagrams need to be updated as frequently as possible so they're useful to technicians coming in alone at odd hours when there are problems.
Training Matters
Anyone working in substations needs to have gone through appropriate training and certification before ever entering the facility for the first time. Training should include ongoing education to keep even veteran professionals up-to-date with current industry and equipment standards.
Professionals working in substations need to know how to conduct themselves safely in a substation for many reasons, including:
Protecting themselves
Protecting the equipment and installation
Maintaining the hardware
Identifying issues
Dealing with those issues proactively
Avoiding wasted time, resources, or outages
Service interruptions might not always be avoidable, but the frequency and severity of them are both preventable. It's worth spending the time and money to prevent wasting far more time and money. Your clients might never know what you did to keep the power running, but your bottom line will.
In Summary
It's the responsibility of utility maintenance companies to see to the maintenance of substation equipment. Whether they own and operate the substations or are hired to care for them, they need to follow best practices, remember why it's important, and always be mindful of the things to avoid.
Clients, residential and commercial alike, are always in need of reliable electrical service. Minimizing service interruptions means that utility maintenance companies need to be assertive in their maintenance of substation equipment. Repainting, cleaning, inspections, and keeping current are all ways to avoid the costly repairs that might happen otherwise.
