Entering Outdoor Substations, Part 5 of 8
Dave Smith has been an Industrial Maintenance Electrician since 1975. He has taught maintenance, troubleshooting and safety courses to thousands of electricians in mines, mills, refineries, factories, plants, power stations and offshore platforms throughout North America and the Middle East. Dave is a hands-on guy and teache...
T he first four articles in this series concentrated on outdoor substations. Now we move indoors. Moving from the outdoors to an indoor substation is like moving from one world to another; the same dangers exist, but they’re packaged differently. When you are walking toward the door of an outdoor substation building, look for damage to its exterior. Explosions split the corners of buildings, wind and storms wreak damage, workers could be on the roof... what you want to see is a building with no apparent damage or danger.
Look in the window and check to see if there is anything out of place, or whether workers are inside. Feel the door and the glass with the back of your hand to sense if there’s any heat.
When you grab the door handle, hang on carefully and tightly so you have control. There have been instances where substations have been brought down because, on a windy day, an uncontrolled door swung inward, hitting equipment hard enough to cause the electro-mechanical relays to trigger. This won’t happen when you’re inside a building, but outside—where it can be windy—this is just one more safe work practice.
Once you’re inside, stop! Don’t move. Use your senses! Smell for any burning smells caused by the overheating of insulation, dust, dirt, etc. Also smell for anything that can be described as extremely fresh air, similar to what occurs after thunderstorms. It is caused by corona that occurs at medium voltages and is extremely damaging to insulation. Corona also reveals itself as a very faint blue glow; inspecting your equipment through your viewing windows with your substation lights turned off may reveal it. It has to be pitch black, and it takes a few moments for your eyes to adjust, so be patient.
Corona also sends out a broad spectrum of ultrasonic sounds; these can be detected by hand-held instruments specifically designed for this and other purposes; one of these should be standard equipment in a substation.
If you are on a ‘beans-and-wieners’ budget, a portable transistor radio set off-station can also detect corona. A radio can be used to detect any electrical arcing, so the next time you are trying to find an intermittent short or open, grab a radio.
Intently listen for any sounds that may be abnormal, especially a sound like bacon sizzling; if it is steady, you have a major problem requiring immediate attention. If you hear a very short sizzle or a pop, it can be the advent of insulation failure and this will repeat many hours later; the time between discharges will get shorter and shorter as the problem worsens.
Many companies conduct infrared surveys assuming they are comprehensive tests but, in fact, they are specific to heat dissipation from poor connections. Corona-damaged insulation will not be detected with infrared surveys, and your detection will
be an explosion or, if you are lucky, your protective system shutting part or all of your facility down.
Every machine has a rhythm, and a substation is no different. Good mechanics and operators know the sounds of their machinery and buildings. Learn the sound signature of your substation. People say to me “Our substation is quiet as a church”. That may be, but there are still sounds of operation.
The truth is, our senses are deadened here in North America: our eyes are overwhelmed with too much to see; our ears tuned only to primary sounds while blocking chatter and other pollutants; our noses reserved for shallow breathing and fine motor skills refined by very few.
At this moment there is a native in the mountain forests of New Guinea standing stock still, centred within a 360º bubble, smelling upwind, listening in all directions, feeling the ground for vibrations and carefully watching; his entire radar system is focused on detecting every possible danger, patiently waiting until he is sure his next actions are safe.
Retiring uninjured is a challenging task for all of us, especially for industrial workers. Learn to move through your days patiently, using your senses as actively as every bushman throughout the world.
Until next time, be ready, be careful and be safe.©