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is not just about what you know,but who you knowthem as each piece is placed allows for some play, reducinghassles during assembly.Radiators and headersAs the radiators are placed onto the tank, it is the assemblycrew’s responsibility to replace each gasket. As the rad isplaced, you might have a little trouble in getting the gasketsto stay inside their seat, but a smear of petroleum jelly willhelp immensely. Glue and contact cements should be avoided,as they tend to cause leaks after they dry (like placing apebble between the gasket seat and the gasket).Just like the conservator and supports, alignment pins andpatience may be the best tools for ensuring an efficient andproductive day.BushingsBushings are the most complicated and difficult pieces of thetransformer installation. The importance of a good installationand the complexities involved with bushings must becompletely understood by at least one experienced memberof the crew who, in turn, must pass the message down toeveryone involved in the process.A complete description of bushing installation is wellbeyond the scope of this article, but here are some tips thatwill lead to a good installation:• A double choker hold using nylon lifting slings is the bestbet for lifting the bushings. At no time should any metallifting device be used in the vicinity of the porcelain ofthe bushings.• Before it is lifted completely off the ground, a thoroughcleaning of the bushing (including the inner shaft) shouldbe performed to ensure no foreign substances will bedropped into the tank.• Don’t be afraid to set down and re-pick the bushing untilthe proper angle is found. It’s much less time consumingto readjust the slings than it is to force an improperlyangled bushing into the tank.• A steady stream of dry air must be flowing through thetank whenever it is opened.• Never attempt to install bushings in wet conditions. Thecore and coils should never be exposed to an outdoorhumidity greater than 80%, as insulation failures maydevelop.• Once the bushings are installed, it is good practice toleave a ground wire on the main conductor to preventthe build-up of potentially dangerous charges.Connections of leadsIf any of the bushings on the transformer are not of the drawleadtype, and must be connected internally, then safety must bethe first concern among workers. Oxygen levels must be monitoredwhenever any portion of a worker’s body is inside thetank. If the transformer was shipped with nitrogen rather thandry air, then a complete evacuation with a vacuum pump musttake place, and the tank refilled with dry air to ensure a properworking environment. Never enter a tank filled with nitrogen.Lead connections should not be made by inexperiencedworkers. The ramifications of dropping a bolt or washer intothe tank can be severe. Large projects have been held upfor over a week simply because the crew had to find, thenretrieve, a bolt that was accidentally dropped into the tank.Other accessories and piecesUnless specifically stated in the design process, it is extremelyrare to find transformers that contain the same configurationand accessories as other transformers you’ve workedon. Each new assembly must be planned beforehand bythe installation crew. This involves reviewing drawings,nameplate data, transformer application, etc. Also, keepingin close contact with the customer and manufacturerwill greatly help the assembly crew formulate a realistic andachievable plan.After assemblyAfter assembly, three more defined steps will occur before aload is placed on the transformer: oil filling and processing;testing and commissioning; and energization. The successof these steps depends directly on the quality of the installationprocess, and due diligence should be followed. Itshould be the responsibility of the crew foreman to stay incontact with both the customer and the crews performingthis work.Transformer assembly can be varied and complicated.There is no possible way to define a hard and fast set of rulesthat applies to each installation. Experience and thoroughattention to detail (particularly at the outset) are the twomajor criteria that will determine the quality of the projectbefore, during and after installation. For any installation, it isimportant that a crew meeting both requirements is selectedto do the work. A transformer’s lifespan is typically about 20years, but many are still in service after 40. A power transformercan be one of the best investments a corporation canmake, but this depends largely on the skill and diligence ofthe assembly crew.Adam Jaques is technical representative, neutral zone operations, withMagna Electric Corp. He got his B.Sc. in Electrical Engineering from theUniversity of Saskatchewan in 2005, and has taken numerous coursesin transformer assembly, design, testing and theory. His experiencein power transformer projects stretches across North America, andincludes supervision, planning and project management.www. mag.com • MARCH 2008 • 21