1,845 Comments Posted by JOE
In any powerplant, you never just walk up and touch any controls. You assume all circuits are live and all equipment can move or start unless you see that it has been locked/tagged out and electrical equipment and conductors have to have grounding cables hung. If you are in someone else;'s plant, unless you have some specific work to do, you touch nothing short of maybe doorknobs and perhaps the water cooler or a cup of coffee. Just because some piece of equipment looks dead, in a running plant, there is a chance of induced voltages, so you treat everything as if it were "live".
I know when I go into the control room at our plant, following an overhaul, to "give back the unit" (release it for return to service), I stand at attention and shake the senior operator's hand. It's a kind of tradition that when an engineer "gives back the unit", you stand at attention and shake hands with the operators and thank them. You "release" your clearance (the formal lock out /tag out), go over the record of all the grounds , and all other records of the clearance. The grounds are cables temporarily place on the electrical equipment and out in the switchyard to groudn things so no stray currents or induced voltages can find their way into the equipment while people are working on it or literally in it. When you and the senior operator are done with that last verification, you have "given back the unit". The senior stands up and shakes your hand and thanks you for a good overhaul. You go "down below" to the crew and tell them you've released your clearance and you thank them- they thank you as well. When you are an engineer in a hydro plant and you are assigned to "hold a clearance", you are responsible for the lives and safety of anyone working on the equipment within your clearance. You rely on the senior operator and he sends out operators from the control room to do the switiching and tag things out. You check each tag and you check with the senior operator steadily. Usually, an overhaul finishes late at night, when the senior can get permission to bring a unit into the grid for testing. It seems like you've finished a journey when you walk into the control room to "give back the unit". You feel a little lost, as for the past period of time, your whole work has been the overhaul and the clearance and it had taken on a life of it's own. When you go to the control to give back the unit, no matter how many times you've done it, it carries a nice weight to it. Seeing this old control room makes me realize power plant people are a strict and proud lot, bound by a sense of responsibility that touches people at the furthest reaches of the grid.
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
Hydro turbines, with large generators turn very slowly compared to steam turbines. It's all a function of how many poles ("magnets") the generator has. The hard and fast number is 3600, which is 60 Hz current x 60 seconds/minute. RPM x number of poles on the generator must = 3600. Big machinery has to turn slow due to centrifugal force, but the rim speeds are up there. Hydro turbines are built custom for each application based on head of water (height), type of flows, and the turbine runner ("water wheel") determines the horspeower and rpm . Oncet hat is in hand, the generator design follows. A hydro turbine turns slower, so a bigger generator with more poles is needed. I've worked on older units that run at 90 rpm. You stand in the turbine pit and look up and can damned near count the poles on the generator rotor. Steam turbines usually run at 3600 rpm, and the combustion "gas" turbines (derived from aviation turbines) turn faster yet. Hydro turbines are friendly, massive machines. Smooth running and generally quiet at openating speed with a nice "60 cycle hum" from the generators and a little dull background roar of the water.
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
black start" itself. If the grid power fails, a hydroelectric plant can be "black started" with no outside power. The older plants like this one could be started by the crew using manual means. A modern plant like a "fossil fueled" (oil, coal or natural gas) generating plant or nuke uses tremendous amounts of power to black start. A hydro plant is most often what jump starts the other powerplants. A hydro plant has big, slow turning machinery and it is kept spit shined and well maintained. A well aligned and maintained hydro unit with bearings properly adjusted will run so smoothly you can balance a nickel on edge up on the generator housing, even when the unit is tripped off line. Been there and done that.
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
This is a little guy as generators and turbines go. I work at a plant where the generator rotor alone weighs 500 tons and turns at 257 rpm.
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
The governor is an extremely sensitive and incredible piece of work. Very fine machine work needede build a governor. To maintain a ballhead hydraulic governor took the finest mechanics. Each unit had its own governor. Without a governor, there is no controlling a turbine's speed so it 's generator could be synchronized into the grid.
- Location: Toronto Power Company Generating Station (view comments)
- Gallery: On the Side of Caution
- Location: Krankenhaus Staacken (view comments)
- Gallery: Climbing Around
- Location: Krankenhaus Staacken (view comments)
- Gallery: Climbing Around
- Location: Krankenhaus Staacken (view comments)
- Gallery: Climbing Around
- Location: Krankenhaus Staacken (view comments)
- Gallery: Climbing Around
The flat box wrenches laying on the plastic sheet are "slugging wrenches". they are the most basic powerplant wrench out there. Slugging wrenches are box wrenches specifically made to be struck with a sledge hammer (AKA "Beater"). Once a nut or bolt is run up tight using plain muscle power on the wrench, it often has to be "slugged up". This is where the slugging happens. The slug wrench has a softer portion of the body designed to take the blow of a steel sledge. At least a 16 lb sledge is used, sometimes a 25 lb.
Three people often are required to slug: one places the wrench on the nut or bolt head and may jam it there with the sole of their boot or with a hunk of wood. The next person has a rope tied thru a hole in the hammer handle, and pulls hard on the rope. These two people have to keep the wrench hard against the bolt or nut and "take the bounce out". When they have the wrench "solid", the third person wales it with the beater.
There are two criteria for how much slugging is needed. If it is possible, an engineer (such as myself), will calculate the "stretch" of the studbolt to produce a given clamping force. Measurements are taken with micrometers or dial indicators once the bolt is snugged. Then, it is slugged and measurements taken again until the required "stretch" is had. The other method is "ring of the wrench", how the wrench rings and how the hammer feels.
Nowadays, slugging and using heavy "cheaters" (pipe extensions) on wrench handles is vanishing. Hydraulic wrenching systems make "breaking" or "making up" big bolting an easy and consistent proposition. I've worked many tubine overhauls where we slugged, and it wore out even the strongest people. We used to rotate the three people, so each took a turn holding the rope while the next person took a turn swinging the sledge. I've seen mechanics and millwrights of all shapes and sizes take their turn slugging. On one turbine overhaul, we had millwrights whose average age was over 65. I was in my 40's at the time. As engineer running the job, I was not supposed to handle the tools. I saw the older men wearing themselves out, so I used to take a turn slugging to give them a rest.
Turbine work is special- the parts are huge, but the degree of accuracy is quite tight. Even those old units would be built to tolerances down in the thousandths of an inch. A human hair is about 0.0015", paper is about 0.,004", so big as those parts are, that is how accurate the work is. A misplace blow of the sledgte can do untold harm when you are working on the turbine or generator, massive as they may be.
You've seen some of the wrenches, but you've not seen the "rigging" to take a unit apart and put it together. The cable slings and shackles even for these smaller old units are bigger than what most people might be used to. Makes the wire rope and hook on a tow truck winch look like a light fishing line.