Power Line Leakages Mar Radio Reception

Radio Record, Volume III, Issue 40, 17 April 1930, Page 3

Power Line Leakages Mar Radio Reception

Concerted efforts to minimise made by Pubiic Works, Power Boards and P. & T. Department

JOR the past year or sod, numerous ‘| letters complaining about power-line interference have been received with increasing regularity from listeners in every province in New Zealand. With the increase, both in the number of radio licenses issued and in the number of districts in which reticulation has been effected, the trouble has become so acute as to necessitate urgent concerted action by the various bodies in control of power supplies. lt is an undoubted fact that people possessing an up-to-date radio set will spend more evenings at home than those possessing no such means of

entertainment, and who consequently are forced to seek enjoyment outside the home, Granting this, it is obvious * that more power in the form of lighting, etc., will be consumed by the setowner. Hence, is it not in the direct interests of the Power Boards throughout .New Zealand to ¢radicate any cause for interference which would . prevent enjoyable rec? ption? Registering Complaints, "THE general opinion seems to exist among listeners that their complaints are totally ignored by the ee ee

¥aliOuUS aulLoricvies connected with reticulation. We can assure them that this is not so. ver since the inception of broadcasting in New Zealand, the serious nature of this type of interference has been realised, and every effort has been made to minimise it. That success has not attended every endeavour As due mainly to two factors: (a) the difficulty of locating a defect that does not reveal its pres‘tence by sparking or sizzling; (a) the indefinite nature of many of the complaints received. As all complaints are finally delivered into the hands of the local radio inspector,‘ our advice to listeners is to write directly to them, giving definite locations of faults. Great care should be taken, however, that the presence of interference can be proved-either by a detect-

ing receiver, by visible discharges, or the presence of corona effects. This latter condition is important, for should the engineer find the fault to lie with the set, or with anything but the power supply, then other complaints would probably be ignored. It is also an established fact that a batteryoperated receiver is occasionally quieter in operation than an all-electric set, because the great sensitivity of the latter, incorporating as it usually does, two or three stages of screengrid radio-frequency, enables it to pick up any interference existing for quite a distance around.

The Controlling Bodies. Most of the complaints received by us lay the responsibility for curing the trouble on the shoulders of three distinct . bodiesnamely, the Power Boards, the Public Works Department, and' the Radio Branch of the Post and Telegraph Department. Nothing definite seems to be known by the complainants regarding the relations and responsibilities of these departments. _ In order to obtain an official ruling on the matter, an interview was arranged between our representative and Mr. Miller, assistant electrical engineer of the Public Works Department. At the outset, Mr. Miller stated definitely that though his department has certain power over the Power Boards throughout New Zealand, it possesses no jurisdiction whatsoever to enforce power suppliers to overhaul their lines unless the latter are so defective as to be a menace to public safety. It appears that though overhead equipment may be faulty enough to cause interference with radio reception, yet it is still passed by the Public Works Department because human life is in no way endangered. Mr. Miller anticipated no trouble whatsoever with the various Power Boards, his experience in the matter being that they are usually only

too willing to rectify any trouble, provided it is located for them. In fact, the engineers of some Power Boards-Taranaki and Dannevirke for example-are already, and without pressure, using multi-valve sets to locate and rectify any interference. "However," concluded Mr. Miller"should any difficulty be experienced, the Public Works Department will be quite willing to make inquiries concerning a Power Board’s indifference to the matter. We cannot definitely promise that this will make any difference, because, as 1 mentioned before, we really have no power to enforce compliance with such a request," Power Board Engineer‘s ‘Views,

R. HOLLANDS, chief engineer and general manager of the Hutt Valley Power Board, supported Mr. Miller’s prediction that power suppliers throughout New Zealand would be anything but antagonistic in considering listeners’ complaints. A statement made by several listeners in their letters of complaintnamely, that Power Boards will not rectify any defects unless they are located for them-was found to be quite correct, and to a great extent justifiable. "Most power suppliers consider that the matter is not sufficiently 1

in their interests to rectify, ’° remarked Mr. Hollands, "and, indeed, if it were, the majority of Power Boards throughout New Zealand are not sufficiently on their feet as yet to justify the engagement of a specially trained engineer for the sole purpose of locating and curing defects. In the future it is highly probanle that such.a course will be adopted," he continued, "but for the present it behoves listeners tv locate any cause for interference themselves." Also, the expense of specially overhauling power lines which are, from our point of view, quite etiicient, would be prohibitive," he concluded. With regard to the cause of the trouble, Mr. Hollands remarked that the binding connecting the power line to the insulators is probably the .chief cause of offence. When the binding is completed and the surplus wire is snipped off, occasionally the tip is (Continued on page 2.)

if By providing amusement in the home, radio is a powerful influence to preserve family life, which modern civilization is threatening. But when reception is marred by interference, the good is offset, and radio loses its appeal. It is incumbent upon’ all to help minimise this nuisance.

DURING late years the radio receiver, as a trouble-free and muchappreciated means of home entertainment, has made rapid progress towards ultimate perfection. At the present time only two important factors capable of marring reception are left-namely, static and power interference. Of these, the latter is curable to some extent, and hence is obviously the next nuisance to eradicate. In many countries the problem has been recognised as being acute, and organised attacks have been made upon this type of interference, with the result that the trouble has, in general, been greatly minimised. Contrary to the opinions of many listeners, however, the problem of interference .is recognised by many New Zealand Power Boards as a serious one, and much time and expense has been devoted to eradicating it.

Public Works and P. and T. Departments * are willing to co-operate with Power — Boards and listeners to overcome or at least lessen interference from power lines. It is in the interests of every listener to -help. these public bodies by reporting promptly cases where interference is prevalent.

Power Interference (Continued from page 1.) not flattened and is left projecting. There is often a discharge from this point, which is quite capable of causing interference. The P.. and:'T. Department’s View. "THE problem according to the chief engineer of the Post and Tele graph Department is the inevitable ‘result of the rapid growth in the "number of radio sets, hence the appar+ ent sudden acuteness of the problem, When the districts were reticulated for electricity they were done so from a point of view of public safety a efficiency. There was no thought of radio. interference, and now the complete elimination of tramway and power interference would involve the replacement of thousands of pounds worth of equipment. In time this replacement will be effected, but the present equipment cannot "be sacriced. SOCEREUEERESAUERERTETERARERELEERERCEREREE SERRE EERE ERY

eT OES S OOS SESS EPS SS SES PSEC PSST SS SESESTS In America power interference assumes a different complexion from what it does in New Zealand, due no doubt to two factors-the greater development of rudio and the fact that electricity is suppliéd by power companies as different from State and ‘Power Board control. Competition is rife, and frequently power lines are duplicated, with the result that small factors (from the electrical. point of view) are often deciding. It has meant. the development of special organisations’ by Power Supply Companies for dealing with radio interference and thus retaining the goodwill of customers. The specific difficulty in the Hutt Valley is due to a fault that. seems ‘ to be difficult to eradicate, It appears that it might be the result.of potential difference between line ani other earth-connected bodies settiug up oscillations: This .would indicate that a possible solution might be found in’ replacing the insulators by

others of a specialised design-a, formidable task involving considerable outlay. Although these difficulties seem col" siderable, much has been and is being done to at least lessen the interference. Hvery complaint received is attended to. In some. instances the trouble is known to. the Department, who are already working on it. Listeners can do a great deal to help the Department and the. power, boards by observing for themselves, In many cases a trouble will suddenly develop and the listener can locate it.by examing the power — lines in his vicinity. Frequently the street lamp will develop a fault that makes itself ‘evident by. intermittent lighting or'a spark that may be seen from the ground, a switch or fuse or a transformer will break down and likewise may. cause a spark or siz#ling noise. By noting thesé. defects land communicating with the power bo@ds the trouble can soon be dealt with. Where the trouble is not apparent the correct’ person to make application to is the district radio inspector. Because a:transformer’ is nearby, many are inclined to blame it for the noise, but only in the cases already PESERERDECUERLETRLRETURESREGEETARELEETCLGRTLEERRTGR

cited does trouble arise from this source. Sometimes, owing to its #eld of supply and the network of Wh radiating from it, a transformer #ill introduce a trouble to an area that is some distance from the source of the trouble. This makes efforts at definitely locating the trouble difficult. There is no wonderful instrumént that can track down a fault mérely by putting it "on the scent." The only method apart from actual observation is by means of a portable set with a loop antenna. The area of greatest intensity can be obtained and then the directional properties of the loop give some. indication of the actual source. The difficulty is considerable when the loop indicates that the inter! ference is of an intermittent: character and is coming from one of the many poles, each with, say, twénty-four insulators and nothing can be seen, (Continued on page 32.)

— Power Interference © (Concluded from page 2.) In eases such as these the sledge hammer is brought into useful ‘commission. By striking the offending pole the noise is increased and then usually frequently located. As can be well imagined, this is a slow process, and the officers of the department who can be spared for this investigational work are necessarily limited. It is in the interest of all those anyway connected with radio to mutually help to reduce the interference. Cooperation between listener, dealer, power boards and Department is essential if the trouble is to be re duced. Listeners can help by making ‘observations, and if these reveal nothing they should communicate with the radio inspector, They are assured that all is being done to help them. Dealers can and have helped in tracing trouble inside the wireless set of the complaining listener. In the Wellington area, at least, there are dealers or their technical men in almost every locality who are willing to help combat the trouble. The listener who finds that the trouble he is experiencing is particular to himself, should communicate with his dealer, who will arrange for someone in his vicinity to listen in and check up. . If the trouble is not experienced by him or others the set is probably the offending link, and here the radio doctor, and not the Department, is the man to see. Between the Department and _ the power and tramway authorities there is close co-operation, and the’ chief engineer could not instance a_ single case where they would not co-operate in the interests of listeners. The Position As We Seo It. HE problem is grave, and the ultimate solution lies with the power boards. The radio receiver will never be entirely free from interference, but it can be very much lessened.

We urge that as reticulation of the country is far from complete the power boards take measures to make the lines not only free from defects that might imperil safety of lifethis they are now doing-but to make them free from radio troubles. This is, possible by the introduction of special equipment, and although no one can expect duplication of existing material, they do ask that steps be taken to obtain this equipment for future lines. — Every consumer of electricity is a potential listener, and as such will rely even more on the lines than before. By doing so he is entitled to service from radio and electrical viewpoint. When interference is noticed the listener should first make sure that the point of origin is not in the receiver itself. This can be verified by communication with the. dealer in his district or other listeners, then endeavouring to locate it himself and reporting to the power board if he is successful. If he cannot locate the fault he should communicate with the district radio inspector who will then give the case attention. But this in itself does not guarantee a cure. Some of the points of origin have been attacked for some considerable time without success. a conclusion, we would state that by no means all electrical interference is caused through power lines. On the contrary, any electric motor incorporating a commutator may cause bad’ interference. An effective cure utilising chokes and large value condensers has béen devised, but its practical application is limited to a certain | extent by the voltage output of the: motor. For example, the average elec-: trie motor as used by picture theatres would require a choke, which, when wound with the heavy guage wire necessary for the purpose, would be of an enormous size in order to secure the necessary inductance. Should any listener locate such a source of interference, however, he would be well advised to seek an expert’s advice on fitting a suitable filter circuit - eS ---