Need of Energy Conservation in Transformer

Need of Energy Conservation in Transformer

Q. State the need of energy conservation in transformer. Explain the use of Epoxy Resin Cast/ Encapsulated dry type transformer from energy conservation point of view. 

Constructional/ Salient Features :

1. CRGO M – 4 or M – 3 grade toroidal cores are wound with secondary enameled copper wire, which is distributed uniformally on the periphery of the core to achieve minimum leakage reactance. Inter-layer insulation is provided to avoid secondary winding short-circuiting in times of fault in the system.
2. Primary winding consists of flexible rope of copper and has the required number of turns in one or more sections. Their ends are crimped and taken out through copper rectangular strips or rods as per customer requirement.
3. Insulation consists of high quality epoxy resin. Initially, the secondary wound cores are mounted and cast in the required mould ensuring minimum clearance as per the voltage requirements. Then the primary winding is cast along with the above in the required mould. Casting is done under vacuum in the epoxy resin cast plant specifically dedicated for the purpose. It has mixing and pouring chambers with controlled temperature and vacuum conditions . Procedure of casting is followed strictly by the resin manufacturer for the particular resin-mix.
4. Curing is done at 1000° C or at room temperature for the specified time depending upon the type of resin used. 
5. Each transformer undergoes all the routine tests before dispatch and is delivered safe at site duly packed. However, following precautions must be observed for its intended performance. Transformer is to be unpacked fully before carrying out side tests. Before energizing all the secondary terminals not in use are to be short circuited and grounded. Primary connection is to be tightened sufficiently to avoid hot connection.
6. As the transformer is fully encapsulated, routine maintenance is limited to clean the outer surface only. 

• The electric field company manufacture indoor type epoxy resin cast current and voltage transformers for stepping down the current and voltage to the measure value.
• The standard value of secondary current is 1 ampere or 5 ampere with different class of accuracy and burden.
• Similarly the standard voltages are 110 volts and 110 V/ √3 with different class of accuracy. The current and voltage transformer together known as instrument transformer.
• The high voltage range is on primary side for current and voltage transformer start from 11 kV, 22 kV and 33 kv. 
• The constructional feature of the current transformer is build with CRGO lamination in the shape of torodical core duly insulated seceondery wounded and wound with insulated sheet thick enough to meet the requirement of system voltage.
• After complete insulation with primary and secondary windings it is casted with epoxy resin in prefabricated mould as per shape, design required. The voltage transformer depending upon single phase one unit or 3-phase single unit are wound with insulated sheet of appropriate thickness as per system voltage requirement.
•  The voltage transformer coil primary and secondary epoxy resin casted in prefabricated mould without insertion of yoke of CRGO core.
• The entire curing of casting instrument transformers is done in HOT CURE SYSTEM with full vacuum before mixing and after drying.

Note : Various indoor models have been tested for fault level upto 31.5 kV for for 3 seconds.