The following have been observed in your 5kVA, 100-440V Al stablizer:
(1) In cases of Al wound stablizers, the customers are not made aware that they are purchasing AVC made of of Al, whereas the customers always desire Cu wound stablizers since they are known more trustworthy than Al. wound AVC. Since they are not know of Al or Cu winding they are dealt on high prices on the market like that of Cu wound. The manufacturer should mark on the stablizer on the stablizer that whether it is Cu. or Al. made, and price not exceeding rupees.
(2) The above AVC is Al wound. To prove not less than Cu. wound its body has been made very heavy, so that, customer may get affected from its high weight and may think that it is Cu wound.
(3) The TF inside the body has been has been shuttered from both sides of the cores, due to which heat dissipation by means of air has been curtailed, i.e. making so shuttering has made heat dissipation of the TF very poor, resultatly the cores of the TF do not get cooled, it is always heated. The above is line AVC so it is always to run. Heat always makes poor day by day or destroys the quality of any product even of very high quality, so expectancy of life of the above AVC cannot be very long. Though on phone talked to your office, I have been told that it has a very good coating of some material, but I am of the opinion that continuous heat makes every thing very poor howsoever it may of the highest quality. These days when there is weather is cool, your TF are still hot.
(4) Though your AVC is technically is very good, but the WIRE USED IS VERY THIN WHEREAS GURU (BLUEBIRD) ALWAYS USE VERY HIGH GUAGE WIRE SAY ABOUT 11 or 12 swg, AS SUCH THEIR AVC DO NOT GET very minutely HEATED and as such their life is very high, say about 20 years or so. Such can never be think of your AVC.
(5) Since your TF inside always high heated so sufficient ventilatioon from the lower side to the upper side must have been made, but you have made very poor ventilation which are very very insufficient to cool your TF even slightly.
(6) DEFINITELY your AVC are technically very good and are ready to surpass other renowned brands on the market, if you would have used winding wire of minimum thickness. That too prferably of aluminium.
(7) Due to the above reasons I do not think that life of your above AVC is long. So I request you if you can supply me a unshuttered TF (or perforforated shuttered) TF made of Cu. wound to replace the present TF inside the above. The minimum possible price for the same may please be intimated.
(8) Whenever so happens, the consumer has no alternate but to bear with such product which he has obtained on high price.