Energy Conservation Techniques In Transformer

• The transformer is said to be in parallel operation when their primary windings are connected to a common voltage supply and the secondary windings are connected to a common load.
• The connection diagram of the parallel operation of a transformer is shown in Figure A.
•  The transformer capacity is a most important parameter when selecting transformer.
• If the transformer capacity is selected over large then the investment of transformer is increased as well as the transformer no-load loss.
• Mostly power transformer gives maximum efficiency at full load.
• If one runs number of transformers in parallel one can switch on only those transformers which will gives total demand by running nearer to its full-load rating for that time.
•  When load increases, one can switch on one by one other transformer connected in parallel to fulfill the total demand in this way, one can run the system with maximum efficiency.

(C) Isolating Techniques :

• Isolation is defined as cutting of electrical supply to the system in order to ensure the safety of thou working on the equipment by making dead those parts which are live in normal service.
• An isolator is a mechanical device which is operated manually and used to open or close a circuit off load. An isolator switch must be provided close to supply point, so that the transformer can be made sale maintenance.
• Devices which are suitable for isolation are isolation switches, fuse links circuit-breakers.
• On three phase LT supplies the triple pole switch with neutral link are provided at the time of isolation to switch should break only the live conductors and the solid link in the neutral should not be removed before opening the switch.
• When transformers are operating in parallel to share a particular load, it is necessary to remove and soul some transformers when load demand is less, so that other transformers will supply energy at maximum efficiency.
• At the time of removing the transformer from circuit first the secondary side load is removed by tripping circuit breaker by opening the load switches (CTP) having high rupturing capacity fuses.
• So that transformer will remain connected to bus, without sharing any load.
• Now the isolator switch on the primary side is opened as they operate on no load only, so that transformer removed from bus-bar completely.
• The isolator in this condition is locked and earthed so that no one else than the operator can use it.
• When it is required to reconnect the transformer again in parallel, earthing of isolator switch is removed first.
• Then the isolator is closed so that transformer is connected to primary side, then either the circuit breaker of load switch is closed so that the transformer will start sharing load in proportion to its kVA capacity.

(D) Replacement by Energy Efficient Transformer : 

• Energy efficient transformers are therefore an important means to reduce transmission and distribution loss. 
• With the improvement of silicon steel properties, the losses of a transformer can be reduced. 
• With new magnetic materials, it is possible to achieve even higher efficiency. 
• The amorphous metal transformer is a modern example of energy efficient transformer. 
• An energy-efficient transformer is very appealing giving its non-stop operation and 25 years service life. 
• These savings translate into reductions in peak loading, lower electricity bills and greater reliable of supply.
• Payback periods vary with the equipment and electricity costs and can be as short as one year or as long as six years or more.
• A transformer can be made more energy efficient by improving the materials of construction (e.g. better-quality core steel or winding material) and by modifying the geometric configuration of the core and winding assemblies.
• Making a transformer more energy efficient (i.e. reducing electrical losses) is then a trade off between more expensive, lower-loss materials and designs, and the value a customer attaches to those losses.
•  For a given efficiency level the no-load and load losses are generally inversely related reducing one usually increases the other. By using energy efficient transformer efficiency improves from 95% to 97% by using amorphous transformers efficiency improves from 97 % to 98.5%.
• By using epoxy resin cast / encapsulated dry type transformer efficiency improves from 93 % to 97%.

Advantages of energy efficiency transformers :