Medium Power Substation Transformers Instructions Document 2.4.06, Revision 4 June 2013 Document 2.4.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers IMPORTANT SAFETY INFORMATION Read these instructions carefully before proceeding with installation, operation, or maintenance of this equipment. Medium power transformers contain extremely hazardous voltages. To prevent death, serious personal injury, or property damage, all information in these instructions should be read and observed.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers Table of contents IMPORTANT SAFETY INFORMATION................................................................................................................................................................... 2 IMPORTANT INFORMATION ABOUT THESE INSTRUCTIONS.............................................................................................................................. 2 Receiving Inspection............................
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers receiving inspection These instructions apply to medium power transformers manufactured by Howard Industries. It is important to read the safety information on Page 2 before attempting any installation, operation, or maintenance activities.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers Tank Pressure The tank vacuum/pressure gauge may indicate positive or negative when the transformer is received, depending on the relative fluid and ambient temperatures. This indicates that the transformer is sealed effectively. If the vacuum/pressure gauge reads zero, this may indicate the possibility of a tank leak, although a zero reading can occur occasionally with changing internal and external temperatures.
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Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers handling Lifting Lifting hooks are provided near the top of the transformer tank for lifting. All four lifting hooks must be used simultaneously. The transformer must not be lifted from any points other than the provided lifting hooks. It is recommended that spreader bars be used to keep the lifting cables nearly vertical, reducing the likelihood of tank deformation or damage to painted surfaces.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers storage Transformer Storage Transformers can be stored if properly prepared. It is recommended that stored transformers be completely assembled. Prior to storage, transformers should be pressure tested according to the instructions on Page 14 (Pre-energization Tests and Checklist). The gas space above insulating fluid should be pressurized with dry nitrogen to a pressure of between two to three PSIG.
Medium Power Substation Transformers Document 2.4.06, Revision 4 June 2013 Annual Inspection The annual inspection should include the following checks in addition to the quarterly inspection checks listed above. 1. Check paint finish and repair any damage. 2. Test insulating fluid for dielectric strength and moisture content. 3. Test insulation with a Megger test set. (Omit if bushings have not been installed.) 4. Check insulation power factor with a Doble or similar test set.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers installation Location and Mounting The transformer should be mounted on a level concrete foundation of sufficient strength to support the weight of the completely assembled transformer. If the transformer is not level, insulating fluid may not circulate properly through the cooling assembly, possibly causing overheating and reduced transformer life.
Medium Power Substation Transformers When internal work is being done on the transformer, dry air should be used to ventilate the inside of the tank. Dry air can be obtained in high-pressure cylinders or from desiccant-type air-drying equipment. When using dry air, the following precautions should be observed. 1. The temperature of dry air entering the transformer should equal to or greater than the temperature of the transformer fluid and at least 10°F higher than the dew point of the ambient air. 2.
Document 2.4.06, Revision 4 June 2013 Filling Installed Radiators with Fluid Follow the steps below to fill installed radiators with insulating fluid. DANGER: TRANSFORMER OIL SHOULD ALWAYS BE HANDLED AS A FLAMMABLE FLUID. SEALED TRANSFORMER TANKS MAY UNDER SOME CONDITIONS ACCUMULATE EXPLOSIVE GASES, AND HANDING OF TRANSFORMERS MAY GENERATE STATIC ELECTRICITY.
Medium Power Substation Transformers 6. Using the fish wire, carefully pull the draw-lead through the bushing, taking care not to damage the insulation on the lead. 7. Install the bushing mounting hardware and fully tighten by alternately tightening opposite corners. For bushings with porcelain flange and clamping flange, torque hardware to 8 ft-lbs. For bushings with metal flange, tighten until the bushing flange has contacted the bushing boss and lock washers are flattened. 8.
Document 2.4.06, Revision 4 June 2013 Installation of Surge Arresters Surge arresters should be installed according to the following instructions and the outline drawing. WARNING: FAILURE TO FOLLOW THESE INSTRUCTIONS COULD RESULT IN SEVERE PERSONAL INJURY, DEATH, OR EQUIPMENT DAMAGE. 1. Carefully unpack and inspect surge arresters for damage. 2. When installing arresters, all mounting feet must be flush with the mounting surface before tightening bolts. Use shims if necessary. 3.
Medium Power Substation Transformers Document 2.4.06, Revision 4 June 2013 8. Delta/Wye and Series/Multiple Switch Settings. Check delta/wye and series/multiple switch settings to make sure they are set correctly. If these connections are made using an internal terminal board, check to ensure that these connections are made properly according to the chart on the transformer nameplate.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers Components and accessories Refer to the outline drawing for a list of accessories furnished with the transformer. Transformer Nameplate A nameplate is supplied on each transformer according to ANSI standard C57.12.00. The nameplate provides certain physical and electrical information about the transformer. Control Cabinet Refer to the wiring diagram for a description of electrical circuits inside the control cabinet.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers WARNING: DO NOT ATTEMPT TO DISASSEMBLE A PRESSURE RELIEF DEVICE. TO DO SO COULD RESULT IN EQUIPMENT DAMAGE AND SEVERE PERSONAL INJURY. PRD’s can be supplied with an optional alarm/signal switch. Refer to the schematic wiring diagram furnished with the transformer. Fluid Level Gauge The fluid level gauge indicates the fluid level inside the tank.
Document 2.4.06, Revision 4 June 2013 Transformer Cooling Fans Optional cooling fans may be provided to increase the transformer load capability without overheating the transformer windings. Operation of the fans is controlled by a contact in the fluid temperature gauge or winding temperature gauge (when furnished) and by an “auto/manual” control switch. Controls for the fans are contained in a control cabinet mounted on the transformer.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers On-Load Tap Changer Some transformers are provided with an on-load tap changer that can change taps while under load, thereby regulating the output voltage. A user-programmable control unit automatically operates the on-load tap changer to maintain the selected output voltage. Refer to the manual provided with the on-load tap changer for warnings and for operating and maintenance instructions.
Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers MAINTENANCE DANGER: THE TRANSFORMER MUST BE DE-ENERGIZED BEFORE BEGINNING ANY MAINTENANCE WORK. FAILURE TO DO SO COULD RESULT IN SEVERE PERSONAL INJURY, DEATH, OR PROPERTY DAMAGE. It is the responsibility of the owner to inspect, maintain, and keep the transformer in proper operating condition. Report all failures during the warranty period to the Howard Substation Transformer Division.
Medium Power Substation Transformers Document 2.4.06, Revision 4 June 2013 Gaskets Visually check all gaskets for cracking or other signs of deterioration. Replace as necessary. When replacing a gasket carefully clean mating surfaces to remove any rust, dirt, transformer fluid, old gasket material, or other contamination that might prevent a good seal. Use an appropriate gasket cement when installing new gaskets. Do not reuse old gaskets.
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Document 2.4.06, Revision 4 June 2013 Medium Power Substation Transformers Instructions for Installation, Operation, and Maintenance of Medium Power Substation Transformers Document 2.4.06, Revision 4 (June 2013) Copyright © 2013, Howard Industries, Inc. Laurel, Mississippi Telephone: 601-425-3151 Fax: 601-649-8090 Web: howardtransformers.
