Transformer Bushings Type STARIP / STARIP -Si Mounting Operating and Maintenance Instructions Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 1 of 17
SAFETY INSTRUCTIONS These instructions are valid for mounting, operation and maintenance of transformer bushings type STARIP and STARIP -Si. Mounting, operation and maintenance works involve followings safety risks: - Perilous, electrical voltages - High voltage - Moving machines - Large weight - Handling of moving masses - Injuries caused by slipping, stumbling or falling Especially rules and instructions for these topics have to be obeyed when handling such equipment. Disregarding of these instructions can include severe injuries to persons, death, damages of products and materials or following industrial injury and/or consequential damages. In addition to these rules national and international safety rules have to be obeyed. In these instructions we have marked risks of injuries or persons and material with following signs near the texts and mounting steps: Personal injuries or fatal damages Industrial injury and/or consequential damages These operating and maintenance instructions are valid for the type range STARIP / STARIP -Si. This regulation is valid only for the respective execution of the bushing in connection with the respective execution specification which includes all technical data and the dimensional drawing. It is an integral part of the operation and maintenance instruction. Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 2 of 17
CONTENT 1 Description... 4 1.1 Design... 4 1.2 Design Head Type STARIP... 4 1.3 Design Head Type STARiP -Si... 4 1.4 Design Head Type STARIP -Si... 4 1.5 Design... 5 1.6 General Operating Conditions... 7 1.7 Mechanical Stress... 7 2 Montage... 8 2.1 Status of Dispatch... 8 2.2 Handling... 8 2.3 Lifting and Erection... 9 2.4 Preparation for Mounting... 9 2.4.1 STARIP Disassembly Draw Lead Bolt, detachable Conductor Bolt... 10 2.4.2 STARIP -Si Disassembly Draw Lead Bolt... 10 2.5 Mounting Draw Lead Bolt... 11 3 Installation Bushing on the Transformer... 11 3.1 Grounding of the Bushing Flange... 12 4 Putting into operation... 12 4.1 Air Release at the Bushing Flange Head... 12 4.2 Evacuation of the Transformer... 12 4.3 Recommended Checks before putting into Operation... 12 4.4 Electrical Measurements... 13 4.5 Test Tap... 13 5 Maintenance... 13 5.1 Recommended Maintenance and Checks... 13 5.2 STARIP -Si Cleaning of the Insulator Surface... 14 5.3 Electrical Measurements... 15 5.3.1 Measuring Procedures... 15 5.3.2 Equipment... 15 5.3.3 Limits... 15 5.4 Thermo-Control by Means of Thermovision... 16 6 Possibilities of repair... 16 7 Storage... 17 8 Disposal after end of operation... 17 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 3 of 17
1 Description 1.1 Design Connecting Terminal Clamping Armature Head Porcelain Housing Silicone Composite Housing Flange with test tap transformer ventilation threaded hole for lifting eyes Fig.1 RIP-Insulting body 1.2 Design Head Type STARIP Design for draw lead bolt or detachable conductor bolt Fig.2 1.3 Design Head Type STARiP -Si Design for draw lead bolt or detachable conductor bolt Fig.3 1.4 Design Head Type STARIP -Si Design for undetachable conductor bolt Fig.4 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 4 of 17
1.5 Design A = STARIP Condenser bushing transformer/outdoor porcelain insulator draw lead design B = STARIP -Si like A, but silicone composite insulator C = STARIP -Si or STARIP design with undetachable current conductor bolt D = like C, transformer side end Main insulation of the RIP transformer bushing STARIP /-Si is an insulating body (20). It is made of a special paper impregnated with epoxy resin under vacuum and wound onto a central tube (19) made of aluminium and coaxially placed grading layers (24) made of aluminium foil to provide uniform voltage distribution. On the transformer side end the inner diameter is increased to accommodate the draw lead insulation, it is screened by an integrated shield electrode (32). This insulating body is installed in a housing, which for type STARIP (A) is a porcelain housing (16) cemented into the bushing flange (29) by Portland cement (25) and sealed by O-rings (26). The head armature is pressed on by plate springs (12). For type STARIP -Si (B) the housing is made of fibre glass re-inforced epoxy resin tube (23) with sheds made of silicone elastomere vulcanized onto it. The bushing flange and the head are glued to the housing tube in a special process and the sheds are vulcanized onto the tube. This type does not have a spring bracing, because the head armature bears itself. The gap between the insulating housing and the insulating body is filled with a dry filler (15), a flexible PU-elastomere, which provides an adhesive joint between surfaces. Therefore these types cannot be disassembled. The flange made of weather-resistant aluminium alloy (29) is equipped with test tap (27), lifting eyes (28) and grounding screws (30). The threaded bores can be used for air release screws in case of glued sealing bearer. C B D 1 23 4 56 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 A Fig.5 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 5 of 17
The head of the bushing type STARIP (A) consists of a cover (11) to close the porcelain housing and plate springs (12), which transmit their compressive force to the porcelain housing via the thrust ring (10) and the bracing nut (9) screwed to the end of the central tube. Cover and thrust ring are made of aluminium alloy, the bracing nut is made of brass. In the top the bracing nut has a slit and a clamp screw (3). This fixes the draw lead bolt (2). In this area the draw lead bolt has two shafts (5), into one of which the locking screw (4,13)) locks depending upon the position of the bolt. On the front side of the bolt there is a screw M12 (1) to pull through the bolt with soldered transformer lead. On the outer side of the locking nut there is an air release screw (8) for air release of the central tube. The head of type STARIP -Si (B) has the same construction in the area of the bolt clamping. The cover (18) is glued to the composite housing, therefore no spring bracing is required and the clamping element (14) for the draw lead bolt is screwed directly to the cover. To avoid corrosion a non-corrosive steel washer (17) is placed between cover and clamping element. As in the STARIP design the central air release screw is located on the outer side. C B 1 23 4 56 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 A In addition to the draw lead design (A and B) there is a design with solid conductor bolt, which is fixed in the bushing head in the same way as the draw lead bolt. Another design is the undetachable conductor bolt (C and D) which is impregnated directly into the core instead of the central tube. In this case no bolt clamping in the head is required. A thrust washer (6) serves as corrosion protection and also presses the upper bolt sealed tight. On the transformer side end the bolt has a fixed, undetachable O-ring sealing (31). D 27 28 29 30 31 32 All sealings are made of oil-resistant Perbunan, the bolt sealings (21) are designed as double radial sealings Fig.5 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 6 of 17
1.6 General Operating Conditions Application: Classification: Ambient temperature: Installation height: Rain level and humidity: Bushing for installation in transformers Epoxy resin impregnated paper, capacitive grading, Outdoor-transformer bushing Outdoor side: - 30 bis + 40 C ** corresponding to temperature class 2 acc.to IEC 60137 Transformer side: daily mean value + 90 C, max. value 100 C ** < 1000 m above sea level. 1-2 mm rain/min. vertical and horizontal acc. to IEC 60060 - I Pollution class : Corresponding to the specific creepage distance *** acc. to IEC 60815 Immersion medium: Oil level below bushing flange: max. oil pressure: Possibility to evacuate: Corrosion protection: Transformer oil of all common types acc. to standards max. 15 mm 200 kpa excess pressure No restrictions regarding level and time Armatures and fixing material made of corrosion-resistant materials Marking: Acc. to IEC 60137 Packing: Wooden case, ventilated, bushing protected by styro-foam cushions below the head and the flange, welded in plastic foil with inlaid dehydrating bags. ** Standard values, Deviations for special cases see corresponding bushing specification *** Standard min. 25 mm/kv for heavily polluted environment. Deviations see bushing specification 1.7 Mechanical Stress Test bending load: Standard acc. to IEC 60137 table 1, class II * Operating load: 50% of the values for test bending load * Standard values. Deviations for special cases see corresponding bushing specification Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 7 of 17
2 Montage 2.1 Status of Dispatch The bushing is dispatched in a ventilated wooden crate. It is supported by styro foam cushions, which are located in the porcelain area and at the bushing flange for the porcelain type and for the silicone type at the bushing head and at the flange. In case of bigger bushings the flange is supported by wooden cross beams. The whole bushing is sealed in plastic foil with desiccant bags added. (Fig.6) In this packaging the bushing can be stored in dry rooms covered by a roof for 12 months. When the bushing is packed in aluminium coated foil instead of plastic foil it can be stored for 24 months under the same conditions. Longterm storage, e.g. for spare parts, can only be made when the transformer side end of the bushing is covered by a metal protection tank with oil filling. The oil filling does not require any special maintenance measures apart from visual checks for leakages. (also see item 7.0) Fig. 6 2.2 Handling To remove the bushing from its crate the type STARIP can be lifted and put down at the flange and at the porcelain housing with plastic ropes or loops. The type STARIP -Si can be lifted and put down at the head and at the flange only, because lifting at the silicone insulator can lead to damages of the sheds, putting the bushing down at the insulator leads to a deformation of the sheds. Surface influenced by moisture The bushing must not be put down on the transformer side end. Even in case of a suitable upholstering there is the danger that in case of bumps cracks develop in the insulating material, which may be not visible, but jeopardize later operation of the bushing. When the transformer side end of the bushing is not protected, it can by handled outside for a short period of time during dry weather. Longer storage, e.g. during rain, is not permitted. The material RIP is hygroscope and absorbs moisture on the surface, which has a negative influence on the operating behavior on the transformer. Dry surface When bushings with clear traces of the influence of humidity are detected, contact the manufacturer. See comparative picture on the left hand side. (Fig.7) Fig. 7 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 8 of 17
2.3 Lifting and Erection Use the lifting eyes on the flange to lift the bushing. On the front side of the connecting bolt there is a screw M12. Into the thread of this screw a lifting eye can be fixed. This lifting eye serves as second lifting point. The bushing is lifted with the help of two lifting devices. This way any required inclined position can be achieved for the installation on the transformer (Fig. 8). Smaller bushings with a weight below 50 kgs can be lifted at the ring screw. The transformer side end of the bushing can be guided manually. Bigger bushings can also be lifted with only one lifting device. For this purpose the ropes or loops are led from the crane shackle to the bushing flange. Another lifting device, e.g. a pulley, is fixed in the same shackle and its ropes or loops are led to the bushing head. By pulling the pulley the lengths of both ropes or loops are adjusted in such a way that the crane shackle is located above the center of gravity of the bushing. The inclination is achieved by further pulling of the pulley. Caution: The lengths of both parts, i.e. rope and pulley have to be chosen in such a way, that the permitted diagonal pull at the eyes does not exceed the permitted angle! (60 from axis direction of the lifting eye) Fig.8 In no case the bushing must be put down with its lower insulating end for erection purposes. This may cause invisible cracks which jeopardize the operating behavior. 2.4 Preparation for Mounting After the bushing was removed from the packaging it has to be put down on bearing blocks at the flange and at the head. The plastic foil is removed do not use a knife for bushings of type STARIP -Si, because the silicone sheds may be damaged. The transformer side end of the bushing has to be thoroughly cleaned if necessary. Do not use heavily vaporizing solvents. Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 9 of 17
2.4.1 STARIP Disassembly Draw Lead Bolt, detachable Conductor Bolt Fig.9 At the head of the bushing type STARIP there are following parts: (Fig.12) 1 Thrust washer (Fig.5/10) 2 Air release screw central tube (Fig.5/8) 3 Locking screw (Fig.5/4,13) 4 Sealing draw lead bolt radial O-rings (Fig.5/5) 5 Clamping screw(fig.5/3) 6 Bracing nut with slit for bolt clamping (Fig.5/9) To disassemble the draw lead or conductor bolt first the clamping screw (5) and the locking screw (3) have to be loosened (Fig.9). After that the bolt is pushed into the bushing by slight beats with a mallet (Fig.10). This is necessary because the friction in the sealing of the draw lead bolt (4) has to be overcome. The draw lead bolt is pushed through the bottom end of the bushing (Fig.11) with the help of a rod (wood or similar) 2.4.2 STARIP -Si Disassembly Draw Lead Bolt The head of the bushing type STARIP-Si consists of following parts: (Fig.14) 7 Clamping element (Fig.5/14) 8 O-ring sealing side clamping element (Fig.5/17) 9 Draw lead bolt (Fig.5/2) 10 Disc (Fig.5/17) 11 O-ring sealing side cover (Fig.5/17) 12 Cover (Fig.5/18) 13 Fixing screws for (7) First the four screws (11) for the clamping element (7) are loosened. Then the whole clamping element including draw lead bolt or conductor bolt can pulled out of the bushing (Fig.15). As clamping and sealing of the bolt have the same design as for the bushing type STARIP, after that - as described above - the locking screw (3) and the clamping screw (5) have to be loosened and the bolt has to be pushed out. Note: In case of a detachable conductor bolt this bolt has to be removed only, if it is required by the arrangement in the transformer. The connection to the transformer lead can now be made. The bore to solder the transformer lead has to be made according to the requirements, max. Ø30 and max. 70mm deep. 1 2 3 4 5 6 7 8 9 10 11 12 13 Fig.10 Fig.12 Fig.11 Fig.13 Fig.14 Fig.15 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 10 of 17
2.5 Mounting Draw Lead Bolt When the bushing is mounted on the transformer the draw lead bolt with soldered transformer lead is pulled upwards through the bushing with the help of a pulling wire or rod while the bushing is led down onto the transformer until the draw lead bolt comes out of the bushing head. (Example pulling wire see Fig.16). Make sure that the diameter of the pulling accessories including their fastening material does not exceed Ø30 mm to avoid a damage of the O-ring while pulling them through. Fig.16 The bold has a conical beginning. When the end of the cone with its big Ø is located flush with the clamping armature, the upper of the two shafts is at the same position as the locking screw (Fig.12/3) and this screw can be slightly fastened. After that the clamping screw is fastened (Fig.12/5) with a torque of 18 Nm. At an interval of 8 mm there is the second shaft. If for tolerance reasons the main lead has to be more tense, the second position can be chosen for the draw lead bolt. Finally the threaded bore at the front side of the bolt has to be shut with screw and sealing. 1 Fig.17 In case a solid, detachable conductor bolt has to be pulled through, we recommend to use a pulling rod (no through-going threaded rod, because the O-rings to seal the bolt may be damaged). screw torque(nm) torque(kpm) 3 Installation Bushing on the Transformer The bushing is mounted on the transformer following the handling instructions for the draw lead or detachable conductor bolt described in 2.3 in reverse sequence. When introducing to the transformer has to be paid attention that the core of the bushing not crash into the edge of the opening If available follow the instructions of the transformer manual. This also applies for sealing and fastening of the fastening screw. If no specifications are existing, the fastening screws have to be tighten for the bushing flange according to table (Fig.18) The given values are reference values and refer to bolted joints with stainless steel screws. Applicable only for flange joints with O-ring seal and metallic contact of the parts. If used with flat gaskets, adequate external brace support is required. Fig.18 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 11 of 17
3.1 Grounding of the Bushing Flange The bushing flange has grounding screws. The flange has to be connected to the transformer tank by grounding bands or cables. Apart from the observation of several national rules this guarantees faultless galvanic connection. It is possible to achieve grounding by a screw with tip. This screw (M12) has to be closed with a cap nut to protect it against torsion and corrosion. 4 Putting into operation 4.1 Air Release at the Bushing Flange Head Before putting the bushing into operation air has to be released from the central tube at the screw (1, Fig. 17) and air bubbles in the flange area with the screw (2, Fig.19). The screw (3, Fig.19) must not be opened, it is used to fill the bushing with dry filler. 3 2 4.2 Evacuation of the Transformer If the transformer has to be evacuated there are no restrictions regarding level and duration up to the operating temperature of the bushing. The material RIP is suitable for such treatment. Fig.19 4.3 Recommended Checks before putting into Operation Visual check of all visible parts of the bushing with respect to external damages, all screws being fixed and tight acc. to instructions, cover of the test tap being tightly closed A leakage check is possible only to a limited extend on the mounted bushing, because the transformer oil reaches up to the flange, but in case of vertically installed bushing not up to the head. The double sealings at the bolt guarantee reliable sealing. Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 12 of 17
4.4 Electrical Measurements The bushings are certified suitable for operation by the routine tests carried out before delivery. It is useful and therefore recommended to carry out a reference measurement on site. This guarantees that is case of later control measurements the measuring conditions are the same and comparable results are achieved. For some transformers these measurements are carried out before the transformer is delivered. In this case comparative data is available already. Measurements include the bushing capacitance as main capacitance C1 and the dielectric loss factor tan delta. Measurement of the capacitance between the last grading layer C2 and the flange is possible, but it does not provide any information about the main insulation. It only shows the condition in the area of the test tap. Description of the procedure see item 5.3.1 1 2 3 4 5 4.5 Test Tap The last layer of the capacitive grading is led out insulated at the bushing flange via a small auxiliary bushing Fig. 20 (2). The contact pin (1) is suitable for the connection of test plugs with a Ø of 4mm. The cover (3) has a contact socket (5) into which the contact pin locks when the cap is closed and provides a reliable grounding of the grading. The cover is protected against penetration of moisture by an O-ring sealing (4). Circuit diagram of the test tap arrangement see Fig. 21 Fig.20 The test taps are not self-grounding! Therefore during operation the cap has to be closed always! 5 Maintenance 5.1 Recommended Maintenance and Checks The bushing is free of maintenance. Check and maintenance refer specifically to the insulator and its condition and the armatures and their condition regarding corrosion. This type of check should be carried out once per year or together with transformer revision. We recommend to carry out electrical measurements of the bushing after the first 5 years of operation, after that depending upon the measurement results every 3 years or in shorter intervals. (see item 5.3.3) Fig.21 C1 main capacitane C2 flange capacitane 1 capacitive grading 2 flange 3 test tap Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 13 of 17
5.2 STARIP -Si Cleaning of the Insulator Surface The silicone compound insulator should not be cleaned regularly. It s good features regarding pollution are heavily influenced temporarily by cleaning, because on the surface there is a water-repellent coating which is removed by cleaning. Cleaning is performed with cloths free of fluffs and soaked with cleaning liquid. As the sheds are flexible do not apply heavy force, but rub more frequently with less force. Cleaning liquid: Wacker E10 from Wacker Chemie, lot size 25 ltr. container, consumption 1 ltr. for approx. 3 5 m 2 of surface. After cleaning the features return to their original condition after approx. 1-2 days. An approximate statement about the condition of this socalled hydrophobicity is made by the HC-classification shown on the left hand side.(fig.22) For testing purposes during wind-still, dry weather sufficiently spray an area of the size of a hand with water from a spray bottle from a distance of approx. 30 cm and compare the image of the drops with the HC-table.(Fig.22) Up to class HC 3 it can be assumed that the features are still sufficient for the operation behavior. It is only a roughly comparing procedure the result of which is no guarantee for the operation behavior. In addition the insulator should be checked for possible discharge traces. Such traces must not occur, because they damage the surface of the insulator in this area regarding its hydrophobicity. In such a case the cause for the discharges has to be investigated. Damages of the sheds or on the body, i.e. shearings, cannot be repaired on site. In case of smaller faults repair in the factory may be possible and have to be agreed upon with the manufacturer. Possible larger remainders of paint can be pulled off after they have hardened do not use solvents! Fig.22 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 14 of 17
5.3 Electrical Measurements Measurements on bushings require experience with measuring. equipment, test set up and the interpretation of the measurement results. This is for some part due to the relatively small capacitance values, which are corrupted by ambient influence of the environment alone. This measurement of the dielectric dissipation factor can be influenced by humidity, weather etc. 5.3.1 Measuring Procedures Mainly the measuring procedures differ by the coupling of the measuring signal. In case of so-called not grounded measurements the test voltage is applied to the conductor of the bushing and the measuring signal is taken at the test tap of the bushing. The grounded measuring procedure is applied, if the bushing which has to be measured does not have a test tap. This is not applicable for the bushings of the type range STARIP and STARIP -Si. The devices required for the measurement are usually equipped specifically for the measurement of bushings. The measurement methods are described in comprehensive manuals. Example of a mobile measuring equipment 5.3.2 Equipment Measuring equipment is available from several manufacturers. Data can be found in the internet or enquired at HSP. (Fig.23) Fig.23 5.3.3 Limits For the measurement the influence of the ambient temperature has to be taken into consideration. In the diagram shown on the left side for C and tan delta the variations through temperature are shown. (Fig. 24) For the material RIP, resin impregnated paper, there are limit values for the deviation of the capacitance and the dielectric dissipation factor with relation the new value. This value is reliably deducted from the reference measurement described under 4.4. In case the deviances are larger than mentioned in the table below, HSP has to be contacted in any case. When there are very large deviations the bushing may have to be taken out of operation. Voltage Level C Deviation < 123 kv 10 % 123 kv 5 % Guide value tan delta 0.004 0.006 Fig.24 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 15 of 17
5.4 Thermo-Control by Means of Thermovision If as a routine thermovision controls are carried out in the installations following items have to be taken into account for the bushings: An increase of temperature by up to 40 K can as a rule be detected at the external contact point, i.e. the lead clamp and is not unusual. Higher temperatures or excess temperatures during low load should lead to a check of the contacts. Irregularities in the temperatures along the outdoor insulator length, though may be caused by hotspots and have to be investigated more closely, if necessary contact the manufacturer. (Fig.25) Fig.25 6 Possibilities of repair Repair is restricted to the parts accessible from outside, because due to the construction disassembly of the composite housing is not possible. These operating and maintenance instructions are valid for the type STARIP /STARIP -Si, therefore in case of a repair sectional drawings and parts lists for explanation are necessary. If the case occurs the documents can be ordered from HSP by quoting the serial number and the specification number and will be transmitted immediately. (Example of a sectional drawing and a parts list (Fig. 26). Above that depending upon repair requirements corresponding short instructions can be given. In case of internal failure the composite insulator has to be destroyed to allow access to the inner construction parts. We recommend to return the bushing to the manufacturer, who has suitable means and measures and professional investigation methods. Fig.26 Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 16 of 17
7 Storage In its original packaging the bushing can be stored in dry rooms up to 12 months. If the bushing is packed in aluminium coated foil with inlaid dehydrating bags, storage time is 24 months. Longterm storage, e.g. of spare bushings, is possible only with protection tank on the transformer side. The material RIP is hygroscope and can absorb humidity, especially in case of long periods of storage. The protection tank is made of spray-galvanized steel and is screwed with sealings to the bushing flange. The tank has a screw through which it is filled with insulating oil, 7% less than the total volume as compensation volume in case of temperature variations. This type of longterm storage has the advantage that checks are limited to visual checks for leakages.(fig.27) Protection tanks 8 Disposal after end of operation The bushing does not contain any liquids, the parts are neither toxic, self-inflamable nor physically burdening. All parts can be disposed of as industrial waste. Fig.27 Following components: - Porcelain (STARIP ), - Silicone elastomere (STARIP -Si) - Fibre-glass re-inforced epoxy resin (STARIP-Si) - Polyurethane Elastomere (dry filling) - Epoxy resin impregnated special paper with aluminium foils as layers - Central tube and armatures made of aluminium alloys - Draw lead or conductor bolt made of E-Cu - Fastening elements, test tap, screws etc. made of stainless steel, aluminium alloy or brass As the insulating body is undetachably fixed to the composite housing by the dry filler it is recommended to cut the bushing above and underneath the flange and the head several time for easy disposal. For type STARIP the porcelain housing has to be destroyed(caution: Danger of chipping!) Service Instructions BAL STARIP /STARIP -Si/02e Visum 01/14 T/gue Page 17 of 17