INSTRUCTION MANUAL CRS Combined insulation bushing

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1 INSTRUCTION MANUAL CRS Combined insulation bushing 5COH CRS REV03

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5 1 SAFETY 1.1 Safety instruction Make sure that any personnel installing and operating the CRS: Are technically qualified and competent Fully comply with these assembling instructions Improper operations or misuse could cause danger to: Life and limb To the equipment and other assets of the operator To the proper function of the equipment Safety instructions in this manual are shown in three different forms to emphasize important information. WARNING This information indicates particular danger to life and health. Disregarding such a warning can lead to serious or fatal injury. CAUTION This information indicates particular danger to equipment or other property of the user. Serious or fatal injury cannot be excluded. NOTE This note gives important or specific information concerning the equipment. 1.2 Specified application These instructions are applicable to CRS combined insulation bushings with rated voltages from 24 kv to 72.5 kv and rated currents from 1250 A to 8000 A. These bushings are designed to operate with the upper part in air and the lower part immersed in the transformer oil. CRS insulation bushings have been designed and produced in conformity with the IEC standards. 1.3 Safety notes on the equipment operation Electrical installation is subject to the relevant national safety rules. CAUTION Installation and fitting the device may only be carried out by qualified personnel and only in accordance to this instruction manual. It is the responsibility of the user to make sure that the device is used for the specified application only. For safety matters, please avoid any unauthorized and improper usage. WARNING All relevant fire protection regulations must be strictly followed. 5

6 2 COMBINED INSULATION BUSHING 2.1 Overall dimensions The following drawings include the overall dimensions of the CRS family of bushings: Figure 1 6

7 Type A B C D D1 D2 D3 F G H Number of sheds Weight mm mm mm mm mm mm mm mm mm mm kg 24-36kV/1250A M30x2 Ø225 Ø225 Ø kV/2000A M42x3 Ø260 Ø240 Ø , kV/3150A M48x3 Ø260 Ø240 Ø ,2 52kV/1250A 65 M30x kV/2000A M42x3 Ø250 Ø240 Ø kV/3150A 85 M48x kV/1250A 65 M30x kV/2000A M42x3 Ø250 Ø240 Ø kV/3150A 85 M48x kV/1250A 65 M30x Ø300 Ø290 Ø kV/2000A 85 M42x kV/ A (1) Ø78 Ø280 Ø320 Ø (1) air side (washer on oil side) Table 1 Type D tank hole (mm) D1 (mm) D2 (mm) D3 (mm) M No. Of bolts 24-36kV / 1250A Ø102 Ø180-Ø M kV / A Ø115 Ø200-Ø M kV / A Ø Ø280 M kV / A Ø130 Ø200-Ø M kV / A Ø140 - Ø250 - M14 8 Table 2 Figure 2 7

8 IEC C/+120 * Standard 2.2 Technical features Rated voltage Rated current Lighting impulse Dry power frequency Partial discharges 1.5Um31/2 Creepage distance Arcing distance Lee protected line min. kv A kv kv pc mm mm mm Pollution P P P P P P P (1) P (1) P4 Operating Temp. load range N C * For -60 C we can deliver a special gasket upon request (1) Lower P.D. values are available upon request Table Operating conditions CRS insulation bushings can be used up to an altitude of 1000 m. For installation at higher altitudes please contact Comem. Ambient temperature of air: -40 C to 60 C (on demand unit -60 C) Transformer oil temperature for normal load: max 100 C daily average: 90 C Temporary over-voltages are allowed in accordance to the standard IEC

9 2.2.2 Capacitance and power factor The CRS bushing capacities are shown in figure 3 and table 4: A A: HIGH VOLTAGE CONDUCTOR C 1 C 3 B: VOLTAGE TAP B C C: MOUNTING FLANGE Figure 3 C 2 Rated Voltage Rated Current Capacity C1 Capacity C2 Capacity C3 kv A pf pf pf ±5 35 ± ±5 60 ±5 15 ± ±5 60 ±5 25 ± ±5 60 ±5 15 ± ±5 130 ±5 95 ± Table Tests Description Reference standard Description Reference standard Capacity measurement IEC Temperature rise IEC Tanδ delta measurement IEC Insulation capacity plug IEC Partial discharge measurement IEC Wet power frequency voltage withstand IEC Cantilever load withstand IEC Dry lighting impulse voltage withstand (BIL) IEC Dry power frequency voltage withstand IEC Tightness test on liquid filled IEC Table 5 9

10 3 INSTALLATION CAUTION The operating and installation requirements described in this manual must be strictly followed. If not, the device can be damaged or a malfunction may occur. 3.1 Assembly on the transformer tank Make a hole with diameter D (see Table 2) in the transformer tank, ensuring there are no uneven surfaces that could cause problems for correct operation of the bushing. The stud bolts for securing the bushing (see Table 2) must be placed along a circumference of diameter D1-D2 coaxial with the hole made previously (Figure 4). Position the gasket provided (Figure 4). The bushing must be positioned as shown in Figure 5, apply a tightening torque of 30 Nm to fix the nuts on the flange. Figure 4 Figure 5 Connect a voltage tap of the CRS bushing to a stud bolt with the cable provided (Figure 6). The end of the cable with the cable terminal diameter 5.3 mm must be correctly secured to the voltage tap using the material provided. The other end of the ground wire must be secured to a stud bolt using a nut and washer. Before performing any operations check that there are no traces of paint on the contact surface. The ground wire must be installed to ensure an electrical contact with minimum resistance. Cable terminal with 13 mm hole, washer, nut Voltage tap Cable terminal with 5.3 mm hole, screw Ground wire Figure 6 10

11 3.1.1 Cable connection CAUTION Electrical connections may only be carried out by qualified, skilled personnel trained in the applicable health and safety regulations of the relevant country. Care must be taken over electrical connection to avoid ionization phenomena. Choose the section of the connections to be used and connect them applying the torque recommended in Table 6 as a function of the rated current of the CRS insulation bushing. Rated current (A) Recommended torque (Nm) /6300 Flag screw: 40 Table 6 CAUTION To disconnect the end nut, keep the other nut fixed to avoid any damage. 11

12 4 OPERATION AND MAINTENANCE 4.1 Packaging All CRS insulation bushings are shipped inside a cardboard box positioned on a pallet to facilitate transport and storage. 4.2 Acceptance Upon receiving the bushing, the Customer must carry out the following operations: examine the outer surface of the packaging to check that it is intact open the packing crate removing the lid check that the fastening elements are intact and well secured check that there are no breakages If damages are found, please contact Comem, providing the data on the shipping list and the serial number of the CRS bushing. 4.3 Rating plate data The rating plate data is indicated on the metal flange of each CRS bushing in accordance with the standard IEC 60137: name of manufacturer standard of reference IEC operating frequency fr rated voltage Um rated current Ir year of manufacture serial number of the CRS insulation bushing 4.4 Storage The CRS insulation bushing must be stored in the original packaging indoors. Permissible storage temperatures are in the range of -40 C to 60 C. 4.5 Lifting The CRS insulation bushing has sturdy packaging; nonetheless, some precautions must be taken during handling to prevent damaging the insulation bushing. Packaged insulation bushing: the CRS bushing must be handled using the pallet. Insulation bushings out of the crate: to remove the insulation bushing from the crate, screw an eyebolt tightly into the upper end of the conductor. The rope for lifting the bushing must be fastened to the eyebolt so that the bushing cannot be damaged during transport. The best position for transport out of the crate is vertical. A horizontal position is not recommended as the silicone sheds could be damaged. The bushing must not be handled using the sheds, as this could compromise correct operation. 4.6 Cleaning Cleaning of the sheds during periodic maintenance of the transformer is recommended. If the bushing has a high level of pollution due to the environment in which it is installed, we recommend cleaning by rubbing the entire surface with a soft sponge soaked in a solution of soap and water at 50 C. The bushing must then be rinsed thoroughly with tap water. Moreover, we recommend cleaning of the sheds at more frequent intervals. 12

13 4.7 Troubleshooting Fault Physical phenomenon Solutions Tighten the stud bolts to the recommended torque of 30 Nm. Oil loss from the flange of the bushing There are hissing noises at the flange There are hissing noises at the connection in air Electric discharge at the air end outside the bushing Abnormal distribution of temperatures in the bushing. Leakage Corona effect Corona effect Electric discharge Thermal effect Check correct positioning of the gasket. Check the surface of the tank to ensure no uneven parts or excessive roughness. The ground wire is not grounded. The ground wire is not connected correctly because the contact surfaces are insulated (i.e. check whether the contact surfaces are painted). Check whether the conductor connected to the bushing has any edges that cause increased electric field density. Check the connection at the air end of the bushing. Check the connections applying the torque recommended in Table 2. Check that the section of the conductors for connection to the bushing is correct If the problem is not mentioned in the cases above, please contact Comem (S.R. 11 Signolo, Montebello Vicentino (VI) - Italy Tel Table 7 13

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16 Strada Regionale 11, Signolo Montebello Vic.No (VI) - Italy Tel Fax