Table of Contents
1. General
2. Drawings and Data
3. Scope
4. Design
5. Construction
6. Tests
1. General
1.1 Description
This specification covers the requirements for the design, manufacture and testing of single or three phase, hermetically sealed capacitor banks for installation in oil refineries, chemical plants, production facilities and other industrial installations.
Additional information for each individual case shall be given in the requisition.
1.2 Standards
Capacitors shall be in accordance with the national standards mentioned in the requisition, IEC Standard Publications, requirements of power supplier and the requirements laid down in the Company specification/requisition.
1.3 Site Conditions
Capacitors shall to suit the site conditions mentioned in the requirements and shall withstand a corrosive chemical and refinery environment, with ambient temperature of maximum 40°C and minimum -25°C and relative humidity of maximum 90%, unless otherwise specified in the requisition.
1.4 Conflicting Requirements
In case of conflicts between the above mentioned conditions and documents, or between them and the specification in hand the severest requirements will govern.
Purchaser will not be obliged to check vendor’s documents such as quotations, order confirmations, drawings etc. He will review them in principle only. It will remain vendor’s responsibility to manufacture the capacitors in accordance with this specification and above mentioned standards in a functional and workmanlike manner.
Deviations from this specification will only be acceptable in case vendor has specified in his quotation under the heading "deviations form specification” the requirements he cannot meet and Company has accepted these deviations in writing before order award or in the purchase order.
Noncompliance will be interpreted by purchaser as confirmation that manufacturer will comply with this specification and any subsequently resulting extra costs shall be borne by the manufacturer.
2. Drawings and Data
Manufacturer shall furnish drawings and other technical data specified in the Company data sheet “vendor furnished documents”
2.1 Drawings and Data to Be Furnished with the Quotation
In addition to the attached capacitor requisition, which shall be completed by vendor, he shall furnish following drawings and data:
2.1.1 Outline drawings showing overall dimensions and approximate total weight inclusive liquid filling, required space etc.
2.1.2 Drawings showing miscellaneous components and auxiliary connections including location of cable box(es), protection devices etc.
2.1.3 Manufacturer’s leaflets giving complete description of the applied accessories.
2.2 Drawings and Data to Be Sent after Order Award
Upon receipt of order, vendor shall submit the following drawings:
2.2.1 All drawings as per item 2.1, however, brought in line with purchaser’s certified requisition/specification and comments received during the bidding stage.
2.2.2 Detailed construction of cable box, exact location of insulators, earthing terminals, protection devices, connection boxes, etc.
2.2.3 The capacitor (bank) neutral point shall be brought out for possible protection purposes. Drawings shall show a detailed construction of this execution.
2.3 Drawings and Data to Be Sent for Construction
Within two weeks after the drawings and data as per item 2.2 have been returned to vendor, he shall resubmit to purchaser the same drawings corrected, where applicable.
2.4 Instructions
Normally, 4 weeks before the delivery date indicated in the order, vendor shall supply installation instructions.
2.5 Transport and Off-loading Facilities on Site
2.5.1 In general, cranes will be available on site, which vendor may use for his own account and under his own responsibility.
Availability of cranes and/or other necessary equipment shall be confirmed with construction superintendent or his representative on site at least one week before arrival of the equipment.
2.5.2 Transport from car, train or boat to the relevant station or building will be carried out:
a. By the equipment manufacturer or by his subcontractor
b. By others if specified in the requisition.
In all cases, the transport, storage and temporary protection of equipment or other handling procedures will take place under vendor’s responsibility and for vendor’s account.
Parts of equipment damaged during loading unloading and transport shall be replaced immediately free of charge and without delaying the final delivery time stated in the order.
Vendor shall remain responsible for transport, offloading and storage of his equipment till final qritten acceptance by field representative.
2.6 Expediting and Inspection
2.6.1 All capacitors and any associated equipment shall be subject to expediting and inspection by Company at manufacturer’s works.
3. Scope
Vendor shalll provide a complete power factor correction unit, free standing complete with all auxiliaries such as but not limited to:
- Rigid steel frame, capacitor units, discharge devices, fuses, audio frequency and harmonic blocking filters, protection relays, all connection strips, power connection and earthing facilities.
4. Design
4.1 Type
The housing of the capacitor units shall be of the welded, hermetically sealed type and, if possible, of the three phase type. Rated voltages of capacitors, whether HV or LV, as well as the other network parameters shall be as indicated in the requisition.Rated voltages up to and including 1000 V are LV above 1000 V are HV.
4.2 Reactors
The oil-immersed reactors applied for blocking or short-circuiting harmonics and/or ripples shall comply with IEC 76.
4.3 Service Conditions
Capacitors shall be located indoors or outdoors as specified in the requisition.
4.4 Enclosure
The capacitor banks shall be completely metal-enclosed and protected against accidental contact with all live and neutral parts. Enclosure shall be fully weather-protected, if capacitors are installed outdoors.
The degree of protection of the capacitor banks in accordance with IEC 529 shall be at least IP 54 for outdoor and IP 40 for indoor installation. The degree of protection on the cable connection boxes shall be IP 55.
4.5 Cooling
Capacitor banks shall be of the naturally air-cooled type.
4.6 Connection
Connection to the switching element will be done by means of cable(s).
5. Construction
5.1 Container
Capacitor containers shall be of a rigid construction to prevent distortion and damage when the capacitor is lifted, jacked or transported. Each container shall be provided with at least one earthing terminal at the lower part of it, size M8 for LV and M12 for HV capacitors as a minimum.
The location of earthing terminals on different units of a bank shall be so that they can easily be interconnected by means of a straight copper strip.
5.2 Each capacitor unit shall consist of a number of flattened rolls of soft annealed aluminum foil between sheets of high quality thermoplastic and/or insulation paper, impregnated with nonflammable synthetic liquid or mineral oil.
A self-healing design is strongly preferred.
Capacitors shall have the lowest possible dieletric losses.
5.3 Discharge Devices
Each capacitor equipment shall be provided with a directly connected discharge device to reduce the residual voltage from the crest value of rated voltage to 50 V or less within 1 minimum for LV and 5 minimum for HV capacitors.
5.3.1 For LV capacitors built-in discharge resistors shall be used.
5.3.2 For HV capacitors, either built-in discharge resistors or phase unbalance transformers suitable to withstand the heat dissipation caused by the discharge current, shall be applied (see requisition).
5.3.3 There shall be no switch, fuse cutoff, etc., between the capacitor and its discharge device.
5.4 The insulation level of the capacitor units in the bank shall be equal to the insulation level of the bank. No extra insulation outside the units shall be required. Capacitor units shall not be mounted on isolator stacks.
5.5 The capacitors shall be suitable for operation at the highest ambient temperature specified in the requisition in sustained overvoltage conditions, mentioned under item 5.6.
5.6 Overvoltage and Overload Conditions
5.6.1 Capacitor units shall be suitable for continuous operation at 110% of their rated voltages, excluding transients.
5.6.2 Capacitor units shall be suitable for continuous operation at a line current equal to 130% of their rated currents, excluding transients.
5.6.3 The overvoltage and overcurrents mentioned under items 5.6.1 and 5.6.2, shall be 115% and 145%, respectively, for maximum six hours within daily load cycles.
5.7 The difference in the capacitance between all three phases of the capacitor bank shall not be more than 15%.
5.8 If specified in the requisition, the capacitor bank shall be provided with facilities such as resistance or impedance increased connection strips to limit the inrush current to a desired value.
5.9 If stated in the requisition that the capacitors shall be used in a system with audio frequency remote control, the capacitor bank shall be provided with proper blocking filters to prevent short-circuiting of the audio control frequency.
5.10 If the existance of harmonics will be stated in the requisition, or blocking filters shall be installed, the capacitors may be subject to extra overvoltage.
In this case the insulation level of capacitors shall be suitable for these overvoltages.
5.11 Capacitors, reactors, etc. shall be of the free-standing cubicle type.
However, LV capacitors may be of the frame mounted type if stated in the requisition. In the latter case the frames shall be of hot-dip galvanized steel, with the same color as the capacitors.
5.12 Protection
5.12.1 LV capacitors shall be protected against internal overpressures,the device shall interrupt the power supply to capacitor unit in the capacitor unit.
5.12.2 LV and HV capacitors shall have built-in fuses protecting the capacitor branches. Fuses shall preferably have an indicator “fuse blown”.
5.12.3 If specified in the requisition, unbalance protection shall be provided by means of three voltage transformers, connected between phases and star point together with a suitable relay with a potential free change-over contact to trip the switching element in the switchgear. The contact rating of the relay contact is given in the requisition. The phase unbalance protection transformers shall then be used for automatic discharges.
5.12.4 For the star-connected capacitor bank, the unbalance protection can be achieved by connecting a current transformer, with a matching protection relay, between the common star points of the capacitance balanced capacitor unit groups.
Insulation level of the current transformer shall be suitable for the full line voltage. Protection relays will be flush-mounted in the relevant switchgear.
Vendor shall provide the protection relays to the switchgear manufacturer in due time.
Note: Care shalll be taken when sizing CT’s with regard to the length of the cable from the transformer to the protection relay.
5.12.5 Each secondary wire from a potential transformer shall run completely in a separate flexible conduit (of isolating material) from the terminal up to the auxiliary connection box.
5.12.6 Secondary wires from current transformers shall run combined in a flexible conduit (of isolating material).
5.12.7 Wiring in the flexible conduit running in compartments with HT live parts shall be routed in a metal conduit or in a metal-enclosed wire way.
Wiring to the outside connection box shall be protected against mechanical damage.
5.12.8 The connection box for protection wiring/cables leave to mounted against the structure. All terminals shall be of the secured type, make Wieland or equal.
Terminals shall be arranged so that the connection of the wiring and cables is possible in a neat way.
Separation walls be provided between terminals for secondary potential transformer wiring.
Terminals for CT’s shall have short-circuit facilities.
5.13 If stated in the requisition that circuit breakers shall form the external protection of the capacitor banks, the cable connection boxes, terminals and all associated parts except the internal fuse protected capacitor branches shall withstand the conditions of through faults when connected to a network with short-circuit capacity stated in the requisition. Ability to withstand this fault for a clearing time of 0.25 seconds will be required.
5.14 Capacitor units and enclosure shall be provided with lifting facilities.
5.15 Capacitors shall be filled with liquid with a dielectric strength of at least 200 KV/cm.
5.16 Strainless steel nameplates and instruction plates shall be provided for the capacitor bank(s) and each capacitor unit; nameplates shall be durably fixed to structure and containers.
Nameplate shall show manufacturer’s data, all electric data , value of discharge resistors, weights etc.
Engraving in nameplate shall be black.
Durable warning signs “danger, high voltage” etc. according to the code of the country of destination shall be mounted durably to the capacitor bank(s).
5.17 Terminal Arrangements
5.17.1 Terminal stems and bushings shall be suitably leakproof sealed into the container, preferably by soldering or welding (in any case no rubber, cork, etc. shall be used). Stems shall be locked against rotation.
5.17.2 If two or more conductors shall be connected to one terminal, provisions shall be made to mount each cable lug individually.
5.17.3 Phase terminals and bushings shall be completely metal-enclosed by a protection compartment.
5.17.4 Terminals shall be marked clearly for phases and neutral (if to be brought out).
5.18 Main air distances for the live connections (including star point between capacitor units and capacitor units and cable terminals).
LV Capacitor Banks
Between live parts minimum 20 mm.
Between live parts and ground minimum 25 mm.
HV Capacitor Banks
Between live parts and live parts and ground.
|
Voltage (RMS) |
Distance in cm |
|
6060- 3600 |
7.5 |
|
3601- 7200 |
10 |
|
7201- 12000 |
12.5 |
5.19 Cable Connections
5.19.1 In principle multi-core conductor cables shall be used.
5.19.2 The cable shall be terminated in a suitable cable box mounted against the capacitor bank wall.
In case connection is made with two cables in parallel, two potheads/glands shall be supplied. Earthing facilities for the cable wires shall be provided inside the cable boxes.
5.19.3 Cable pothead shall be supplied complete with all necessary installation materials such as, but not limited to, solder cones, cable connectors, etc. All cable glands and cable potheads will be part of vendor’s scope of supply.
5.19.4 The copper connections between the cable box and the bushings shall form part of the supply.
5.20 Cable supports shall be provided welded to the capacitor bank frame for mounting the cables underneath the cable entry.
5.21 The Frame and the Enclosure over the Terminals
The frame on which the capacitor containers, reactors, metering transformers etc. are mounted shall be of the welded construction.
The frame on which the capacitor bank is mounted needs not to be used for housing the components during transport, except if vendor’s standard design provides for transport also.
Over all live parts a metal enclosure, (degree of protection IP54) shall be provided, encapsulating the phases and the star point connections, whilst the star point connections are separated from the phase connections by means of a complete metal separation. The transformers shall be housed in a metal enclosure.
The enclosure shall be supported on the frame and not on the capacitors etc.
Care shall be taken to avoid collection of condensate in the enclosures.
5.22 Finish
Capacitor containers, blocking choke, frame etc. shall be shot-blasted zinc sprayed (minimum thickness 60 micron) and painted with one layer of redoxyde primer (minimum thickness 30 micron) finished with two layers of coating each of a minium thickness of 30 micron, color: RAL 2004.
6. Tests
6.1 Capacitors shall be subjected to the following tests:
6.1.1 Measurement of capacitance and check on phase-balanced capacitances, calculation of output.
6.1.2 Measurement of losses.
6.1.3 High potential AC or DC voltage tests between terminals.
6.1.4 High potential AC voltage tests between terminals and container (dry test for indoor type capacitors and wet test for outdoor types).
6.1.5 Measurement of residual voltage against discharge time.
Note:Above mentioned tests shall be carried out in rated frequency unless otherwise specified in the requisition.
6.2 The following tests shall be carried out only if specified in the requisition:
6.2.1 Thermal stability test.
6.2.2 Ionization test.
6.2.3 Test on impedance and insulation level of reactors in accordance with IEC 76.
6.3 Tests shall be performed in the factory, however, high voltage tests shall be repeated at site.
6.4 Tests at factory shall be performed by vendor and for his account. All required equipment and tools for testing shall be provided by vendor. Purchaser or his representative may witness the tests. For this purpose, vendor shall inform the purchaser about the date of tests two weeks in advance.
6.5 Vendor shall prepare test reports and submit the required number of copies to purchaser.