Flow Meter Terminal Boxes

Transcription

1 Shutter Flow Meter Terminal Boxes Shutter Flow meter Terminal boxes

2 Shutter Valve DAROC Description and general specifications Production range and operating conditions Operation Installation, setting and putting in service

3 Description and general specifications. Transformer conservators are usually arranged in such a way that, even at minimum level, the oil is always above the highest point of the transformer lid. When a leak occurs in the tank, due for example to a broken bushing, the oil in the conservator pours out, thus considerably increasing the danger of fire and pollution. The automatic conservator oil shutters DAROC Series DS and EDS-R have been designed to prevent the oil contained in the conservator from flowing out when a leak occurs and, for Series EDS-R, to signal this by an electric contact. Main features of the DAROC shutters Series DS and EDS-R are: They are mounted on the pipe from tank to conservator, in series with the Buchholz relay, so they can be used both on conservators with free oil surface and on conservators with rubber bag; The operation is completely automatic. When, due to a leakage in the tank, the oil flow rate from conservator to tank exceeds a set value, the DAROC valve closes the pipe thus preventing the loss of the conservator oil; Should the DAROC valve trip unduly, because of a malfunction or of particular working conditions, a pre-set by-pass valve operates automatically and prevents the internal depression in the tank from becoming excessive; The DAROC shutter has to be reset manually after tripping; if requested an additional by-pass pipe allows to reset the valve from ground level. The shutting-off of the pipe between tank and conservator is always an abnormal operating condition; it is therefore preferable to choose the DAROC Series EDS-R shutter in order to have a warning by electric contact that the valve has tripped. Production Range and Operating Conditions. DAROC Series DS and EDS-R shutters can be fitted to pipelines of nominal diameter 50, 80 or 100 mm; The valves can be equipped with one or two electric contacts and can operate under following conditions: Oil and ambient temperature range : -25 C to C (standard version) Oil features ( standard version ) : Mineral oil Oil viscosity 30 cstk at 20 C Please note: with other oil viscosity the flow rates change according to the setting diagram Vibration resistance : 3 g on all axis Check resistance : 10 g on all axis Maximum operating pressure : 1,5 bars Maximum test pressure : 3 bars By-pass valve setting standard version 0,4 bars Degree of protection : IP 65 Casing : made of cast aluminium and has two flanges for mounting onto the pipeline which connects the tank to the conservator. One flange has threaded holes and a gasket groove so that the device can be fitted directly to the Buchholz relay. On casing two windows allow to visually check the operation of the device and two oil drain screws allow to empty the casing of oil if needed. The adjusting device and, if requested, the resetting by-pass pipe are also assembled on casing. The casing is closed by a cover which includes the terminal box for DAROC contacts equipped valves series EDS-R, a gas drain cock and the nameplate, which shows also the direction in which to mount the DAROC valve on the pipe, are attached to the head. 3

4 Operation. During the operation of an electric transformer several conditions may occur which cause an oil flow in the pipe between tank and conservator: During the heating phase an oil flow from tank to conservator is observed, due to oil expansion as the transformer heats up; the flow rate is usually <= 30 dm 3 /min; During the cooling phase an oil flow from conservator to tank is observed, due to oil shrinking as the transformer cools down; again the flow rate is usually <= 30 dm 3 /min; If a leakage from the tank occurs, for instance if a bushing breaks or a pressure relief valve pops up and doesn t close correctly, it is observed a flow from conservator to tank with a flow rate usually >> 30 dm 3 /min. The first two conditions occur in normal service and should not cause the shutter Series DS and EDS-R valve to trip. The shutter is designed to trip automatically when the third condition occurs, thus stopping the oil flow from conservator to tank and preventing the oil in the conservator from being lost and slowing down the rate at which the oil seeps out at the leak. The shutter doesn t operate when the oil flows from tank to conservator; it trips when the oil flow from conservator to tank exceeds a set value. To operate correctly, the valve has to be set so that the admitted oil flow from conservator to tank is the maximum that will occur during the cooling phase. So, when a leak in the tank causes the oil flow to exceed the maximum set the valve will close and prevent the oil in the conservator from being lost. Damping System To take into account peaks of flow speed caused by accidental occurrences such as start up of pumps, elasticity of the tank or of the radiators, the closing of the main valve is retarded by a hydraulic damping system, which stops the valve from closing for flow speed peaks. After tripping due to an oil leak from the tank, the main valve has to be reset manually, either by the adjusting device or by the optional by-pass pipe. If the valve trips during the cooling phase, not withstanding the damping system described above, the valve will open again automatically during the heating phase, when the oil will start to flow from tank to conservator. Overpressure Valve Operation The main valve may close even in absence of a leak in the tank, for example when the oil in the pipe is very cold and therefore has a viscosity much higher than expected, or if the initial regulation has not been correctly done. In this case, the shrinking of the oil due to the cooling will cause an increasing negative pressure in the tank, while the cooling phase lasts. To limit the value of this negative pressure an overpressure valve has been built into the DAROC shutter. Installation, Setting and Putting in Service. Installation The DAROC shutter must be fitted onto the pipe between tank and conservator. The flange has a gasket groove and threaded holes in order to be able to fit it directly to the Buchholz relay. The gasket is supplied with the valve. If DAROC Series EDS-R is chosen, the electrical connection to the terminals has to be made according to the wiring diagram attached inside of the cover of terminal box. Setting The DAROC shutter is supplied set to the maximum stroke of main valve. In fact, when there is a leak in the tank, the flow rate is usually considerable higher than the flow rate admitted by the valve at full stroke with oil of normal viscosity. 4

5 Taking into service After installation and setting it is possible to put the device in service by filling it up with oil. Maintenance The DAROC shutter doesn t need any particular maintenance; it is however advisable to check the correct operation regularly. Resetting of main Valve If the main valve closes accidentally during the cooling phase of the transformer, it may be necessary to reset it without having to wait for the heating phase. This can be done either by the forced opening screw or by the re-setting by-pass. Finish In standard version, all cast parts are protected by one coat of two-pack epoxy primer and one coat of twopack polyurethane paint, final colour RAL 7031 and screws and washer are of stainless steel; the degree of mechanical protection is IP 65. Therefore the device is suitable for outdoor usage even in tropical climate and with high industrial pollution. Special versions are available for particularly severe climatic and/or aggressive atmospheric conditions. Performances of contacts Magnetically operated, normally open, normally closed or changeover contacts. Contacts material : gold Operating temperature : - 50 C C Breaking power : 150 W 400 VA Insulation : 2000V 50Hz between terminals and earth for a 60 seconds time. Maximum current : 2 A Minimum and maximum tension : V Contact resistance : 500 mù 5

6 Shutter DAROC Type: EDS-R 6

7 Oil Flow Meter for Power Transformers type: SCFR - 2 Description and general specifications Operating instructions

8 Description and general specifications. Characteristics The circulation indicators Series SCFR2 ( Oil Flow Indicators) are designed to check the circulation of dielectric fluids, normally mineral oils, into the cooling plants of electric power transformers. It is possible to use said indicators with other kind of fluids too. Only it is necessary to use the right materials which are compatible with the circulating fluid. The circulation is optically indicated by an indicating pointer that shows on a dial if the oil is circulating or not. The optical indication may be not proportional to the flow velocity. The indicator can be equipped with one or two contacts that operate alarms in case the flow speed inside of the pipeline is lower than a minimum acceptable value. The operation of the indicator Series SCFR2 is based on the dynamic thrust of the flowing oil on a detection paddle placed inside of the pipe; the dimensions of the paddle depend from the diameter of the pipe. An adjustment device allows the triggering point to be modified within certain limits, also after the indicator mounting on the pipeline, in order to adapt it to the real flow conditions. Field of use The circulation indicators Series SCFR2 may be used with the following characteristic values: pipeline diameter : from 80 to 400 mm flow speed : from 0,5 to 3,0 m/sec fluid : mineral oil pressure inside of the pipeline : from 0,0 to 5,0 bar working temperature from : - 20 C to C resistance to vibrations : up to 3g on all axes resistance to shock : up to 10g on all axes Special features Basing to the experience of the previous series, special features have been included in the design of the circulation indicators Series SCFR2, with the aim of simplifying the choice of the device, granting easy interchangeability and allowing the user to adapt the operating characteristics to the actual needs. The big dial diameter and the bright colors of the figures and of the pointer consent easy reading from distance too. The construction si made in two separable parts: mounting flange, with detection paddle and adjustment system, and indicator case with optical indication and alarm contacts. This construction allows the indicator case removing for repairing or substitution or during the shipment of the transformer. the transmission of the paddle movement is made by means of a magnetic transmission thus granting a complete seal. the adjustment system is simple and reliable; the adjustment can be made even after the device has been mounted on the pipeline. Operation instructions. Construction features, finish and accessories Case : aluminium alloy. Gray color painted In standard execution, all cast parts are protected by one coat of two-pack epoxy primer and one coat of twopack polyurethane paint, final colour RAL Screws and washer are in stainless steel Closing ring : aluminium. Gray color painted Lens : tempered glass Paddle : brass Degree of mechanical protection : case=ip 55 contacts =IP 67 Therefore the device is suitable for outdoor mounting even in tropical climate and with high industrial pollution. Special versions are available for particularly severe climatic and/or aggressive atmospheric conditions. 8

9 The device is supplied with its assembly gasket. A cable gland is supplied on request. Wiring diagrams and contact performance As mentioned above, the circulation indicators Series SCFR2 can be supplied with one or two electric contacts. Contacts Performances : 5A 250 VAC 0,25A 250 VDC 0,5A 125 VDC Special contacts for electronic circuits having low current (1 to 100 ma) and voltage (4 to 10 V) can also be supplied. Operation The circulation indicators Series SCFR2 operate as follows: the oil flowing in the pipeline hits the detection paddle, thus causing the shaft on which it is mounted to rotate by about 90 against the force of the return spring; the dimension of the paddle is chosen according to the diameter of the pipe and the oil flow that it should detect; the tension in the return spring is pre-set at the manufacturing workshop in the middle of the adjustment range set; the set point may however be further adjusted by turning the adjustment assembly after removing the fixing screws; this adjustment can be made with the flange mounted on the pipe; the magnetic joint transmits the rotation of the paddle to the indicating pointer and operates at the same time the switches. Mounting, adjustment and maintenance Mounting The device is mounted on a flanged stub pipe, welded directly to the pipeline; the dimensions of the stub pipe should be as indicated in drawing N To mount the device on the pipeline, separate the indicator head from the flange by removing the lateral screw and rotating the instrument by about 10 anticlockwise so as to free the screws from their holes; then attach the flange to the pipe by screws M8, with the assembly gasket in groove. After having attached the flange to the pipe, assemble the instrument's head on to the flange again and check that the optical display is operating correctly by starting up and stopping the circulation pump. If it is correctly working, make the cable layout according to the desired wiring diagram. If the optical or electrical indications are not correct, carry out the adjustment described later. In order to make sure the signal paddle is hit by the most uniform possible flow, avoid mounting the device immediately downstream of bends, necks or other parts which could cause turbulence in the flow. If this is impossible, the adjustment of the tension in the return spring, allows the indicator to be adapted to the real flow conditions. Adjustment The device is always supplied with the adjustment assembly set to position 3, so that it is possible to both increase and decrease the load of the return spring in order to set the device at a higher or lower flow rate. If the factory setting is not satisfactory adjust the setting as follows: remove the indicator head from flange as described above in order to get to the adjustment assembly fixed on the flange by four screws. remove the four screws; even if there is pressure in the pipe the adjustment assembly cannot come off the flange; furthermore a gasket continues to guarantee the seal; turn the adjustment block until the notch corresponds with one of the numbers on the flange, anticlockwise to increase the force of the spring and trigger the device at a higher flow rate, and clockwise to have the opposite effect; replace the 4 screws and re-assembly the indicator's head on the flange; then check that the adjustment made has the desired effect otherwise make a further adjustment. Maintenance 9

10 The circulation indicators Series SCFR2 do not need periodic maintenance; however it is advisable to check regularly that they are operating correctly by starting up and stopping the circulation pump and checking that the optical and electrical display takes place as normal. Order specifications When ordering it is necessary to indicate the type of device according to the table in drawing N , the diameter of the pipeline, the mounting position and the required wiring diagram. Standard cable entry thread is ¾.; should another thread be preferred and a cable gland be needed, this has to be mentioned in order. 10

11 Terminal Boxes Series SM2 Description and general specifications Operating conditions Quality control tests

12 Description and general specifications. This specification concerns the function, the main features, the range of types, the assembly and operation of the terminal boxes Series SM2. Environmental and operating conditions depend generally from the compatibility of the materials and components and from the surface treatment. Function The measurement, control, check and data recording circuits for medium and high power, oilcooled, oil-insulated electric transformers require medium and low voltage and current signals to be brought outside of the tank. The terminal boxes Series SM2 are designed and constructed to face this need since they offer oil-tight conductors protected with a flanged casing and accessible through cable entries. Construction features The terminal boxes Series SM2 consist mainly of a flanged casing, closed by a cover, inside which are mounted the terminals. One end of the terminal is wired inside of the transformer tank while the other end is wired outside the tank through threaded cable entries. The following data apply only to the terminal boxes Series SM2 fitted with M6 terminals. General specifications Flanged casing with lowered bottom to prevent air pockets; the casing has one or more cable entries and it is closed by a cover; the mechanical protection degree is IP 65; identification labels inside and outside of the box allow identification of terminal box as well as of terminals; The cable entries are threaded to customer request and supplied on request either plugged by brass plugs or with brass cable glands with gasket; Terminal boxes are supplied with the number of terminals requested by customer; The standard terminal is one-piece conductor threaded M6 at both ends for connection of a Ø 6 mm cable terminal; oil-tightness is obtained by O-Ring gasket; The terminals are designed and mounted so that they cannot twist when the cable terminal is screwed on and have a Snap-On ring to prevent accidental loosening during transport, handling and mounting; they are evenly spaced so that they can be connected by connecting plates supplied on request; The terminals are supplied with copper washers; inside of the tank self-locking nuts are used to assure secure, vibration-proof wiring while the connection inside of the terminal box is assured with nut and counternut; Terminals are numbered on both sides to ease cabling and allow identification; Special M10 terminals are also available. Materials and finish Casing and cover of aluminium casting, painted with one coat of epoxy primer and one finishing coat of polyurethane paint, colour RAL 7031; the epoxy primer is compatible with mineral transformer oil at a temperature of up to 120 C, the paint passes the 500 hour salt fog test; Nylon insulated nickel plated brass terminals with copper washers and vibration-proof nuts; Terminal gaskets of fluor silicone rubber; External screws and washers of stainless steel; Cable entries are closed by plastic plug during shipment. Operating conditions. Environmental temperature with standard gaskets - 20 C to + 50 C Relative humidity 95% at 20 C; 80% at 40 C; 50% at 50 C Protection degree of box IP 65 Operating temperature (mineral oil) -20 C to +110 C Insulation to earth of terminal at 20 C > V Standard M6 terminal cross section 12 mm2 Special versions can be supplied for other environmental conditions 12

13 Quality control tests. Following tests and controls are performed on boxes before despatch : Insulation test of terminals towards box; test voltage 3.000V; Tightness test of mounted terminals by compressed air and immersion in water bath; test pressure 1 bar; Control of correct numbering of terminals. Range of types The terminal boxes Series SM2 are produced in 4 types as follows : Type SM2-X Dimensions to drawing N Number of terminals from 2 to 6 Number and dimensions of cable entries 1 to 2 - max ¾ or PG 21or Ø 35 mm Type SM2-S Dimensions to drawing N Number of terminals from 2 to 12 Number and dimensions of cable entries 1 to 3 - max 1 or PG 29 or Ø 40 mm Type SM2-L Dimensions to drawing N Number of terminals from 2 to 36 Number and dimensions of cable entries 1 to 3 - max 1 or PG 29 or Ø 40 mm Type SM2-XL Dimensions to drawing N Number of terminals from 2 to 47 Number and dimensions of cable entries 1 to 4 - max 11/2 or PG 42 or Ø 50 mm Drawings showing the construction of the terminals: Terminal M6 N Terminal M10 N Assembly and operation It is advisable to prepare a wiring diagram for each terminal box before assembling, showing the identification of the terminal box, which can be engraved on the terminal box identification plate, and the correspondence between the wire identification and the number of the terminal. Terminal boxes Series SM2 are then mounted on the transformer tank as follows : the wires inside of the tank are first connected to the terminals on the bottom of the terminal box in accordance with the wiring diagram; for easy wiring and record it is advised to write the wire identification number on the identification plate inside of the terminal box cover in correspondence to the number identifying the terminal; the terminal box is then bolted to the tank; the flange O-Ring gasket assures oil-tightness; the external wires are then led inside of the terminal box through the cable entries, there to be connected to the external part of the terminals; each wire has to be connected to the terminal following the numbering previously set up; if necessary one or more terminals can be connected by conducting plates that can be supplied separately; when the wiring is finished close the cover of the terminal box. 13

14 TERMINAL BOX SM2-X 14

15 TERMINAL BOX SM2-S 15

16 TERMINAL BOX SM2-L 16

17 TERMINAL BOX SM2-XL 17

18 18

19 19

20 Terman '90 S.r.l., Via Ghisalba, 13-20/21, Bollate (MI) Italy. Tel: , Fax: , E- Mail C.F./P. IVA IT C.C.I.A.A Trib. Milano Reg. Soc Cap. Soc