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Application Elymer Electromechanical Ferraris type electricity meters are suitable for measuring active energy (kWh). - in single phase for direct connection up to 100A. - in three-phase four-wire networks at balanced or unbalanced load for direct connection up to 120A. in three phase three or four wire networks for CT operated measurement at balanced or unbalanced load. Design Their up-to-date construction provides a wide measurement range of load current. The accuracy class of these meters is Class 1 or Class 2. Elymer meters are designed and manufactured to ensure:
Specifications All measuring and technical characteristics of electromechanical meters comply with requirements of IS:13010, IEC- 521 and BS 5685, with their latest amendments, and various other national specifications. Meter frame The electromagnetic drive system, the disc, brake system, cyclometer and the adjustments are mounted with spring loaded fasteners on a SiAl alloy die cast four point fixing robust meter frame, which ensures high physical strength and endurance. The design of frame ensures nil deformation over prolonged periods in installation. The modular unit components can be easily replaced (without disturbing any other) in the event of repair. All holes are drilled and tapped in one setting to ensure consistency. Single phase meters are also available with pressed steel frame of two mm thickness with all fixing holes punched in one setting. Drive system The voltage circuit has a double magnetic circuit, and characterized by its low watt-loss, assures excellent dielectric properties. It has negligible effect of auto heating caused by the power loss in the voltage coil and cause no effect on the meter characteristics. The voltage electromagnets are wound on a coil of thermoplastic material, encapsulated in a thick heat shrinking sleeve allowing high breakdown strength and making it dust and moisture proof. Each voltage circuit is provided with a disconnecting device, both inside and outside in the terminal block, accessible only on removal of meter cover or the terminal block cover for test purpose. The current electromagnets, made of laminated silicon steel sheets is of U form. Electromagnetic sheets of a corresponding initial permeability in current cores assures specified error curves with respect to the load, either at small loads or high overloads. Upper Bearing The upper bearing is an axial rotor guide, where a highly polished stainless steel pin slides in a polished brass or self lubricating thermoplastic bearing, capped on the rotor shaft. The pin is rounded to prevent any damage to the bearing surface. A brass sleeve with the pin is fastened to the meter frame. Double Jewel bearing The rotor bearing is standard version of meter is made of double jewel, consisting of a ball, free running in between two sapphire stones with ball shape halves. Its natural frequency is designed in such a way that the external noise does not effect it. No lubrication is necessary. Magnetic suspension bearing In meters with magnetic suspension bearing, the repelling field of two annular magnets is used to completely compensate the rotor weight. The upper part is pressed on the rotor shaft with moulded guide and the lower part is fixed to the meter frame together with a highly polished guiding pin. The bearing has negligible time-constant friction with assures a long life for the meter. Cyclometer Register The register is cyclometer type with five or six digit wheels moulded from self-lubricating acetal copolymer, dimensionally stable to wide temperature variations. The readings are shown in kWh with one decimal (or no decimal) and without using any multiplication factor. The periphery of the last drum is subdivided into 100 sections. The register shall not complete an entire cycle when submitted to full load for at least 1500 hours. The low friction register does not require any kind of lubrication. The register framework is fastened to the meter frame, with one screw duly guided for accurate placement, so that the worm and worm wheel is properly engaged even when the counter is replaced. The fictional torque of the register is negligible even at low loads and does not change with time. The digit size of 5x3mm is available with standard counters. Large digit size of 6.9x 3.7mm with jumping figure is also available optionally. Our standard meters are fitted with a reverse running stop device with hardly discernible friction, having no effect on meter accuracy. Unidirectional counter (optional) The Unidirectional cyclometer counter is a special mechanical design which registers energy consumption, irrespective of whether the rotor disc is moving in the forward direction or in the reverse direction. Meters are fitted with a reverse running stop device which prevents the reverse movement of rotor disc and de-registration of counter. However, in that case, if the meter is connected reverse, energy consumption continues without registration which is direct loss of revenue. With optional unidirectional counter instead, available for single phase meters, positive registration of energy consumption continues even if the rotor moves in the reverse direction. RR stop is unnecessary. Rotor Mechanism The rotor disc (two discs for three phase meters), made from high purity and high conductivity aluminum, is graduated in 100/200 divisions on its upper surface for accurate calibration and testing. Removal and reassembly of the rotor disc assembly is simple without involving any alteration to the original positioning. The worm on the rotor spindle and worm wheel connecting to the cyclometer is made self lubricating long life polymer. The direction of rotation is from left to right when viewed from the front of the meter. Terminal Block The terminal block is moulded from insulating non-hygroscopic flame retardant phenolic/polyester compound, highly resistant to creep current. It is fastened to the base, so that access to meter interior is not possible when the cover is on. The incoming and outgoing terminals are made of nickel plated solid brass, with two screws in each terminal to accept cables up to 25mm2 for and up to 40A and 50 mm2 for and up to 100A. Conically shaped holes enable easier insertion of conductors. The flashover and creep distances, between metal parts of individual circuits on one hand, and terminal and outside contact parts on the other, are large enough to assure high breakdown strength. The extended lower part of base protects terminal block against mechanical effects. Braking Element The high energy brake magnet functions independent of the position of the disk in the electromagnetic gap. It is made of four pole Alnico magnet with high coercivity die-cast in SiAl alloy, is securely fixed to meter frame, and is insensitive to external magnetic fields or an accidental short circuit. A wide range of rotor speed settings are possible by moving the whole magnet, or find speed setting is possible with micro-metric control. Adequate temperature compensation is provided. Accessible Adjustments All calibration facilities are capable fine adjustment with adequate range. - High load adjustment by shunting the flux of the four pole magnet, which is rigidly fixed to the frame, and changing the braking torque on the disc of the meter. - Low load adjustment that balances the effect of the voltage circuit flux. - Phase shift/Inductive load adjustment varying the resistance of current flux shunt on a resistance strip. Its rigidity assures high stability of the phase adjustment. In addition, the meters are also provided with accessible creep adjustment. In three phase meters, torque balancing of elements is also possible. Characteristic Curves of Electromechanical Meters Technical Details of Electromechanical Meters |
