The accuracy of a meter is tested by drawing calibration curves showing the percentage departure from absolute accuracy in its reading for various decimal fractions of full load.
Owing to the cost and trouble of weighing a large number of zinc plates, this type of meter fell into disuse.
In this meter the electrolyte is a solution of mercurous nitrate which is completely enclosed in a glass tube of a particular form, having a mercury anode and a platinum or carbon cathode.
This current is small, however, and the meter is not operated until a much larger current is passed through it.
Calls are registered by pressing a key, which connects a battery through a position meter of very low resistance to the socket of the line jack, thereby furnishing the necessary energy to the meter.
The position meter just mentioned is common to all the cords on one position and records all completed calls handled at the position.
Some administrations, in addition to employing the ordinary position meter, use a second one for registering ineffective calls.
The improvements introduced in 1890 and 1891, whereby this state of affairs was put an end to, consisted in the introduction of the principle of supply by meter, and the adoption of a comprehensive system of reducing the initial pressure of the gas, so as to diminish loss by leakage.
ELECTRIC. METER In the public supply of electric energy for lighting and power it is necessary to provide for the measurement of the electric energy or quantity by devices which are called electric meters.
Edison, the last-named inventor elaborating a type of meter which he employed in connexion with his system of electric lighting in its early days.
By the use of a permanent magnet instead of a shunt coil as the bob of one pendulum, the meter can be made up as an ampere-hour meter.
In Intermittent Registering Meters some form of ampere-meter or watt-meter registers the current or power passing into the house; and a clock motion electrically driven is made to take readings of the ampere-meter or watt-meter at definite intervals - say, every five minutes - and to add up these readings upon a set of registered dials.
When this is the case, the number of revolutions of the meter in a given time is a measure of the watt-hours or energy which is passed through the meter.
Since the revenue-earning power of a supply station depends entirely upon its meters, inaccuracy in meter record is a serious matter.
The cost of measuring current by the aid of a meter is made up of three parts: (I) the prime cost of the meter, which varies from £2 to £6 for an ordinary 25-light house electric meter; (2) the capital value of the energy absorbed in it, which if the cost of the energy is taken at 2d.
Per Board-ofTrade unit, with interest and depreciation at 6%, may amount to £10 per customer; and (3) the annual working costs for repairs and also the wages of the staff of meter men, who take the required monthly or quarterly readings.
The Edison electric meter, like those of Sprague and Lane-Fox, was based upon the principle that when an electric current flows through an electrolyte, such as sulphate of copper or sulphate of zinc, the electrodes being plates of copper or zinc, metal is dissolved off one plate (the anode) and deposited on the other plate (the cathode).
This meter is an ampere-hour meter and applicable only to continuous current circu; ts.
Hence when a current is passed through the meter, the armature rotates and increases its speed until the driving force is balanced against the retarding force due to the eddy currents in the copper brake disk.
It can be constructed to be either an amperehour meter or a watt-hour meter, but is usually the latter.
In the Long-Schattner electrolytic meter, the insertion of the coin depresses a copper plate or plates into an electrolytic cell containing a solution of sulphate of copper; the passage of the current dissolves the copper off one of the plates, the loss in weight being determined by the quantity of the electricity passed.