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ilp archive : journals

public lighting no. 44 vol. 12
January-March 1947

Editorial p11
Light - Symbolizing Progress p11
"If there are quiet sermons in stones, there are undeniably tremendous messages for the for the future in light - a word which symbolizes almost all the progress that men have ever made. I have always felt that there was a particular satisfaction in being associated with the business of putting more light in the world. We cannot forsee a poiont at which the quality and efficiency of light sources cannot be improved." - C. E. Wilson, President of the G. E. Company. Putting more light into the world is right. Unfortunately, as far as street lighting is concerned, a retrograde step has been taken in recent months, by causing less light to shine in the world. It is necessary, to reiterate what has been stated already - for goodness sake, for safety's sake, for the sake of all road users, let more light be visible for street lighting.
The fear of some in authority is that brighter lighted streets would cause a psychological repercussion with the public - the question would be asked "Why this extravagance in street lighting, whilst we, the public, are told to cut down our lighting to a minimum?" But, when the real cause is made known and explained, either by radio or press, most peopel can appreciate the good reason for the action taken.
Lighting: Energy

Safety First p11
"Safety on the road" should be the slogan for every authority. "Keep death off the road" should be on every hoarding. To attain this degree of safety, ever road should be well lighted - main roads in particular. Badly lighted roads are a cause of accidents - that brighter roads at night means greater safety for all road users. Saving of fuel, by cutting down street lighting, is infinitesimal when compared with the total output of coal. The public would respond to the appeal and would understand.
Lighting: Energy, Lighting: Safety

1947 Conference p11
The APLE has accepted the cordial invitation of the Mayor and Corporation of Southport to hold the next Conference in their town. An important sessional meeting, with the subject of Safety First as it pertains to street lighting, will be held in the Floral Hall.
APLE: Conference

Outside Demonstration p12
The delegates will have an opportunity of witnessing a demonstration in a series of selected roads. Both electric and gas, and Group A and Group B roads, are at the disposal of the manufacturers for this demonstration.
APLE: Conference

The Programme p12
The Conference will extend from the afternoon of Monday, September 15th until Friday 19th. On the opening day, the Annual Meeting will be held, and the incoming President, Mr. Thomas Wilkie, will be installed. To conclude the Conference on Friday 19th, a coach trip is arranged for a visit to the Liverpool docks and an opportunity to see the lighting of the Mersey Tunnel. A special session is being arranged for Wednesday 17th, when the subject of Safety First, with particular reference to road lighting is to be discsused from differing angles. The meeting will be of a special character and the Council is inviting various Associations to contribute their views on the subject.
APLE: Conference

Competition Paper p12
The Council is offering a prize of 25 guineas for the best paper on "Safety First on the Highway". To include the essentials for road safety, with special reference to road lighting. The competition is open to all. The author will be invited to present it at the morning session of September 17th.
APLE: Conference

Some Experiments In The Lighting Of Traffic Roundabouts by K. F. Sawyer, B.Sc., A.M.Inst.Gas E. (Gas Light And Coke Company) p13
Reproduction of the paper Some Experiments In The Lighting Of Traffic Roundabouts.
Lighting: Distibution, Lighting: Theory

Inauguration of Street Lighting Control at Tynemouth p24
Centralised control of street lighting throughout the County Borough of Tynemouth, by means of the D.C. Bias System, has recently been installed. The new system would save the Borough £1000 minimum in wages. Councillor J. Mayo told how in 1939 he had seen models of equipment which they thought might be of service to the town, and he mentioned its war-time developments at Bethnal Green, it being possible for wardens to receive preliminary warnings over the network of air raids. Peacetime applications of the system were not limited to the control of street lighting by also included load shedding - in this way water-heaters and cookers could be switched off to help the Ministry of Fuel.
600-700 street lamps could be controlled by a single button. The system utilises the existing power mains to convey the operating pulse to switching relays which are housed in each column. The operating pulses are injected into the low-tension network of each substation, from which the street lamps are fed, by the pulse transmitting apparatus known as the Biassing Equipment. Central Control of the Biassing Equipment in each substation is carried out from the Master Controller by means of control pulses transmitted over telephone pilot-wires which exist between all substations.
Lighting: Control, Lighting: Installations

Automatic Control for Electric Street Lighting by S. A. Daines p25
1. Introduction
Some form of control of street lighting has been, and will continue to be, essential. As in other spheres, the human element has been displaced gradually by the mechanical or electrical contrivance. The latter years of the war brought into sharp focus many new aspects of the subject. Only those authorities who had the foresight and capital to install "master switch control" were able to give their citizens, stage by stage, the full benefit of brighter street lightign when permitted by the Ministry of Home Security.

2. Features of Automatic Control
To be efficient, the automatic switching apparatus should infallibly switch on the lamps as soon as natural light falls below a certain minimum value, and conversely, must switch them off as soon as that minimum is exceeded. Dependent upon this is: (1) The economy of electrical energy used by the connecting load; (2) The lengthing of the useful life of the lamp.
For the matter of exactly when the lighting should be switched on or off, consult A New Lighting-up Timetable Based on Illumination Requirements. Using "dusk" and "dawn" in their widest sense, it is believed that most authorities have two stages of street lighting: (i) Full lighting from dusk to approximately midnight; (ii) Half or "Police" lighting from midnight to dawn. Full lighting could also be implemented from 6:00AM to dawn for early moring travellers.
Every Public Lighting Engineer is faced sooner or later with the problem of where to install the control apparatus. Without knowing the distribution system layout, the condition of the cables, whether or not pilots are available, the number and situation of feeder pillars, substations and other data, then no other Engineer can help them decide between individual post or block of substation control.
Generally some form of group control is the wiser choice. If switch wires are not already available, the opportunity to provide them will arise from time to time by virtue of the area being re-cabled or other purposes, such as change-over from single to three-phase, or the general increase in load. Thus, in the recabling of an area, one can provide at an economical price, the necessary switch wires capable of serving the full and half lighting of the public lamps. With columns at 50-yard intervals, the cost of the switch wires is favourably comparable with the cost of the automatic switching device which would otherwise be required per column. Where the cost per automatic switch exceeds £2 10s. 0d., one is left with a balance which can be allocated towards excavation and reinstatement charges. There are very few dependable devices at a lower price.
Subject then to limitations imposed by voltage drop, bearing in mind the ultimate loading of the type of lamps to be used, a network of block-control points gradually takes shape. Further the all-too-scanty space left in the compartment of each column for control gear is free to house the fuses, choke, condenser and the like, whilst the somewhat delicate switching device finds a more weatherproof housing in a feeder pillar or substation. The latter situation results in lower maintenance costs. So labour costs will be reduced as it is easy to fix or remove apparatus from a well-spaced substation under cover than he will from a cramped cubby hole of a lamp-post in the open.

3. System Of Automatic Control
There are many thousands of the hand-wound time switches still in use, but to the progressive Engineer such control switches, with the essential recurrent visits for winding, setting and regulating, are becoming no more than failful servants with a record of a job well done.
Much better are the electrically wound patterns or the synchronous motor-driven types, especially if they have solar dial attached and so dsigned for different latitudes, together with settings allowing for compensation for longitudinal variations. Combinations of these patterns are available and very great use is now made of the synchronous motor, either continuously run, or merely for winding the spring mechanism. 100% availability of supply is essential to the plain synchronous motor-driven pattern. Whilst the technique of self-starting synchronous motor design is improving rapidly, it would appear that more attention still should be concentrated on finding the ideal bearings and the lubricant to gowith them, for most stoppages are due to gumming of the lubricant, possibly because of the heat emanating from a continuously alive coil winding. With a never-failing source of supply, an improved synchronous, motor-driven switch, complete with solar dial, but without reserve spring and mechanism, which accounts for costlier maintenance is an ideal to be aimed at.
The automatic control of street lighting, or more particularly traffic islands, "keep left" signs, and similar important points, has been met with an extremely popular device which uses the daylight intensity as the actuating medium. A light sensitive cell, of the "photo-conductive" class, is incorporated in a circuit in such a manner as to increase the charge on a condenser as the illumination falls, until the potential across the condenser finally reached a point when it is forced to discharge through a parallel-connected discharge tube. The discharging current passes through a relay which in turns performs the operation of switching on the controlled lamps in circuit. By means of a polarised relay and change-over device, a similar operation in reverse, switches off when daylight returns.
Another pattern, using a thermionic valve, which is normally replaced once per annum, operates more efficiently and also has the advantage of being so designed as to switch on the lighting controlled should any component become defective whilst on circuit. Theoretically this system is excellent, for it automatically takes care of latitude, longitude, the clarity of the atmosphere and the proximity of adjacent high buildings. In practice, it finds a very successful application at traffic circuses, bollards and the like, but lacking soem of the advantages of the systems yet to be described, it does not appear to have an appeal so great as to become a universal controller of the bulk of street lighting.
Another form of control is useful in the linking up of existing group control points on the cascade principle. Starting at the beginning of the first circuit with an automatic device such as a time switch, use is made at the end of the circuit of a non-tilting mercury switch with time delay characteristics, used in conjunction with a latched-in contactor, controlling the next group. The contactor for each group is thus operated by the current flowing in the preceding circuit.

Superimposed Current Systems
In latter years the tendency has been to perfect and to apply the technique of superimposing onto the transmission and distribution systems various forms of electrical impulses which differ in form and frequency from the normal power transmitted. The impulses are injected into the system at some suitable feeding point, whilst discriminating relays, installed at reception points, are tuned in such a way that they reject the influence of the normal power, but accept the superimposed energy.
One method perfected for use on alternating current networks only, places a direct current bias between the phase and neutral lines at each local substation, in such a manner as to be capable of extraction at any point. Use is made of a 6-volt heavy capacity battery in conjunction with double-pole reverseing switches and contactors which can be made automatically to connect the D.C. Bias to the network at the sub-station. At each control point, a polarised type of relay which is constructed to accept the D.C. signal and to neutralise the effect of the normal A.C> supply, is made to operate a relay coil and switch for controlling the connected load. The system was an advance in the direction of locally controlling larger areas of public lighting, but was inomplete as an entirely centralised method of control without the availabiliy of pilot wires between the main station and the substations. More recent progress has been made in this matter, and apparatus is now available by which a second signalling D.C. bias can be applied to the extra high-voltage network between the central control station and the substations fed thereform.
There are two systems, somewhat similar, which superimpose ripple frequencies on teh entire network in such a manner than a truly centralised method of control is possible. One system uses a high-frequency signal of several seconds' duration, whcih vibrates a tuned reed and this in turn actuates a ratchet wheel and a mercury switch for circuit control. The other uses two high-frequency ripple currents per signal, and by means of turned reeds used in conjunction with a thermostat heater and a delayed-action thermally-operated vacuum switch, the automatic control is effected.
Another method superimposed on a complete electricity distribution system, at a central point of the network, an audio-frequency current rhythmically interrupted. The frequencies used are 1500 and 800 cycles per second, the former for street lighting control, the latter for ARP devices. A multiplicity of channels is then provided by using at each frequency a number of differently timed impulses, one being selected per switching operation. Switching relays, connected in lamp columns or substations, function as receivers, and operate on a dual selective principle by means of an electrical filter for frequency response, and a mechanical filter, consisting of a spring-controlled swinging armature, for rhythm response. The whole equipment is push button controlled at the central station, or from selected remote control points, whilst an operation such as the normal switching on and off of street lightign is made entirely automatic by the fitting of solar dial time switches in the signal initiating circuits.

Experience with a "Rhythm Control" Installation
The area covered by this installation is 200 square miles, with rural and urban supplies for every conceivable type of load. The town feeders are supplied from each of the three bus sections at 6.6kV to over-ground substations and under-ground sectionalisation points, and thence the supply is transformed to 400/230V or 365/210V for local use.
Previous to the installing of the superimposed current system, the Borough lightign was controlled mainly by synchronous motor type of time switch mounted in each column. The rural area was a mixture of hand switches, and electrically-wound time switches, the latter generally controlling switch wires. As opportunity arises, the Borough street lamps, of which approximately 60 per cent are still individually controlled, are being grouped on switch wires and controlled from 23 substations. A typical substation control point, showing relay for "full" and "police" lighting, together with the associated 50-ampere contractors, are shown.
With regard to maintenance costs of relays and contactors, but the approximate figure per relay is 4s. 9d. per annum, made up of 2s. 8d. per annum for actual overhaul and repair, together with 2s. 1d. for the cost of removing, refixing and transport to the Repair Department. Adjustments and tests on the relays, of which there are 1,100 on circuit, are carried out by a qualified mechanic from the Meter Test and Repair Department, and public lighting attendants are especially warned of the delicate nature of the relays. The reliability of the system is now reaching 98%.
On the transmission side, negligible maintenance has been required, but in the eight years during which the equipment has been installed, considerable modifications are being made to the general transmission system, plans are now being made to adapt both the method and the point of injection to the new and future conditions. As the equipment has also been used extensively for A.R.P. purposes and will be used for "off peak" load control, the initial expense and annual cost of maintenance has been and will be borne proportionally by thee functions as well as by street lighting.
Innerconnections by the National Grid will require cooperation by authorities. It may be that each authority will be allocated a particular frequency band but then that would restrict their applications somewhat. The present frequencies extend from 400 to 1500 cycles per second, and in view of the fact that lower frequencies become difficult to separate from the 50-cycle power, whilst the higher ones tend to attenuate in certain circumstances. On the current installation, it was being considered whether to standardise on 800 cycles and abandon the 1500 cycles.
Regarding the future, the next step possible is radio control. Unless the hidden secrets of war-time inventions throw up some apparatus applicable or adaptable to public lighting control via the medium of radio, it is believed that these systems will hold the field for the next 10 to 15 years.
Lighting: Control

Old - and New p30
Picture of a granite concrete lighting column outside Hereford Cathedral. (It was identified in the next issue.)
Lighting: Installations

Brighter London Streets p31
Central London Electricity Ltd., had developed tungsten lamp lighting scientifically to its limit before the war abd were searching for an alternative form of electric lighting to give improved illumination in important shopping centres. The high pressure types of electric dischrage lamps did not provide a good colour and were unsuitable. It was considered that the new fluorescent lamps had great possibilities. Their use in this new role represents the first major developments in street lighting technique since the war.
The trial installations which were sponsored by Central London Electriciy Ltd. with the co-operation of Westminster City Council and the Royal Borough of Kensington are located in Old Bond Street and Brompton Road. As a result of these trials there will be a revolution in the methods of lighting busy shopping centres.
Features of the new lighting are the absence of glare and the pleasant character of the light which preserves the natural colours of the surroundings. The fluorescent lamps give better light than has been seen in the streets, and their output is two and a half times as great as tungsten lamps of equivalent wattage.
The lamps are 5 ft. long and have a low surface brightness so there is an entire absence of "dazzle". The Brompton Road installation (carried out by the General Electric Co., Ltd.) gives the "Daylight" effect. It consists of 10 lanterns, each using seven 80-watt fluorescent lamps in 5 ft. lengths. Each lantern consume 630 watts and gives much more light than a 1000 watt tungsten. It is an example of applying the new lighting to a wide road and six lanterns are on columns on central islands while four are mounted over the outer kerbs.
The installation in Old Bond Street which was carried out by the British Thomson-Houston Co. Ltd. employs "Warm-White" fluorescent lamps. Eight lanterns have been erected, each accomodating three 80-watt 5-ft. lamps. The lanterns are spaced at intervals of 80 feet and suspended at a height of 25 feet above the centre of the roadway by means of catenary wires. Each lantern consumes 300 watts and gives more light than could be obtained from one 500 watt tungsten filament lamp.
London has given a lead for safer and better street lighting. It is certain that this lead will be followed by towns and cities, not only in this country, but all over the world. There is no doubt that this system has come to stay.
Lighting: Installations

Proposals to Amend the Patent Law by S. T. Madeley p32
Within the last year about 320 patents have been granted in connection with appartus for electric discharges in vacuum, confined gas, and vapour, and for incandescent and arc electric lamps.
In view of the conditions created by the war, and the general advance in the arts, it was deemed that amendment to the Patents Act was due.
A list of points was then made concerning the changes to the Patent Act.

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