W~z.9810 sln~--- -- B2S~ W2to" 10 a --

0.0306.25.9810 = ~ / ) . 1 5 2 . 3 . 5 2 .10_8.85 ~ " .314.108 = --0.012,

--40',

Thus with a negative angle ~ of 40' only, over-compensation occurs. Hence when it is required to increase the galvanometer sensitivity by means of compensating the mechanical counteracting momenu, a smooth variation of angle r should be provided.

It should also be noted that when the counteracting moment is compensated,the resulting specific restoring moment is decreased,which leads to a deterioration of the zero stability; the compensation of the mechanical moment should, therefore, be carried out only ,within certain limits.

Above examples only dealt with the calculation of the basic galvanometer parameters.

The technique of designing the galvanometer for maximum efficiency, maximum sensitivity, etc. is in the main the same as for moving coil instruments.

L I T E R A T U R E C I T E D

[1] V. O. Arutiunov, Design and Construction of Electrical Measuring Instruments [in Russian] (GEl, 1949).

[2] A. M. Melik-Shakhnazarov, Some Peculiarities of the Operation of Ferro-Dynamic Null Indicators [in Russian] (Works of the Azerbaidzhan Industrial Institute, ed. 11, 1955).

[3] A. M. Melik-Shakhnazarov, G. A. Alizade and T. M. Alley, Zavod. Laboratoriia , No. 7, 1953.

[4] N. P. Volkov, Priborostroenie, No. 2, 1957.

[5] A. M. Melik-Shakhnazarov, Izmerital 'naiaTekhika, No. 1, 1957.

[6] A. M. Melik-Shakhnazarov, G. A. Alizade and T. M. Aliev, Zavod. Laboratoriia , No. 6, 195&

[7] A. F. Kulikovskii, Electrical Measuring Instruments for Checking Boring Processes [in Russian] (Gostop- tekhizdat, 1952).

A PORTABLE SET FOR T E S T I N G E L E C T R I C I T Y METERS

V. S. S h e i k o

Following a suggestion made by the author of this article the VNII (All-Union Scientific Research Institute) of the Committee for Standards, Measures and Measuring Instruments has developed a portable set for testing electrical power and va meters as well as phase meters, wattmeters, ammeters and voltmeters of class 1.5 at the factory premises and in particular during inspection testing.

Although relatively light and small this set is technically as good as rack-mounted devices and in some respects even better.

Figure 1 gives the schematic circuit of the set. Current and voltage adjustments are made by means of autotransformers RT of the LATR-2 type. In order to ensure smoother current and voltage adjustment in single- phase measurements the set includes a switch Sw which transfers the first phase autotransformer to the "load s terminals of the second phase. It is then used as a second adjusting stage (fine adjustment).

In order to decrease the weight of the set, specially made light load-transformers LIT-I~T are used, and all the adjusting and standard transformers ST type LATR-2 and 1-54 are mounted without their cases.

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sw ,1 V . . . . ,

Wattmeter

Wattmeter ",q,,Z20 V

J' Sw t ~

Fig. 1.

The phase shifter Ph8 is made up of components of two motors, the rotor being the moving part of the electric plane type 1-24a of the "Elektroinstrument" plant (Daugavpils), which has a three-phase star-connected winding, and the stator belongs to the motor made by the 2nd Mechanical Artel (Moscow) which has a special winding for working from a supply of 220 or 380 v.

The phase shifter weights 8.5 kg and its dimensions are 180 x 180 x 180 mm.

The set is mounted in two cases, one contains all the voltage circuit components including the phase shifter, the other all the current circuit components. Each case weighs 40 kg and has the dimensions of 50 x 40 x 25 cm.

The set works from a three-phase supply of 220 or 380 v. The phase shifter and the adjusting transformers can be set to operate from either voltage.

In Fig. 1 the set is shown to be connected .to a supply of 220 v without a neutral conductor.

The top panel of the voltage case contains (Fig. 2) terminals for connecting the set to a three-phase supply of 220 or 380 v; a three-pole switch 2; fuses 3 for a nominal current of 2 a; terminals 4 for connecting the instru- ments to be measured; three pairs of terminals 5 for connecting standard instruments (wattmeters or voltmeters); switch 6 which transfers the autotransformer for fine adjustment purposes; (Sw inFig. 1); switch 7 for adjusting voltmeter ranges to 150-a00 and 450 v (VSw in Fig. 1); switch 8 which provides wattmeter circuits for testing various electricity meters without changing connections on the wattmeters themselves (W Sw in Fig. 1); switch 9 for parallel wattmeter circuit ranges (PWSw in Fig. 1); switch 10 connecting voltmeters for phase or line voltage measurements; three voltmeters 11 of the E-421 type, each with three ranges of 150-300-450 v, for measuring phase voltages and selected in such a way that their basic errors do not exceed those for class 1.5 instruments.

In the center of the panel there is l~nob 12 connected to the phase shifter worm-gear. The phase shifter provides an adjustment of the voltage phase with respect to the current from 0 to 120". At the bottom of the panel regulators 13 are mounted; they consist of three autotransformers type LATR-2 which provide a voltage adjustment from 0 to 450 v.

The upper current case panel (Fig. 3) contains: terminals 1 for connecting the set to the three-phase supply; a three pole switch 2~ fuses 3 for a nominal current of 2a; test terminals 4; three pairs of terminals 5 for standard instruments; switch 6 which transfers the autotransformer for fine adjustment purposes (Sw in Fig. 1); three type E-421 ammeters connected by means of instrument current transformers type 1-54 for measuring phase currents.

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Fig. 2. Fig. 3.

The middle of the panel contains jacks 8 connected to three instrument current transformers supplying wattmeter and ammeter testing circuits. Trans former ST switches are ganged with toad transformer LiT switches so that measuring ranges and loads are switched simultaneously. The bottom of the panel contains current regulators 9 which consist of three autotransformers type LATR-2.

Standard instruments are not provided in the set since they are usually available on the spot, and since their inclusion would have increased considerably the weight and size of the set.

The set can be used in travelling laboratories particularly in GAZ-69 vans which have been adopted by the Commit tee for Standards, Measures and Measuring Instruments for inspection laboratories. In this connection it is convenient to have permanent racks in the van for mounting electricity meters.

For testing purposes the two halves of the set are placed side by side on a bench with three wattmeters between them connected to terminals on both cases marked "Wattmeter." The wattmeters must be of the ASTD type, since range multipliers for this type of wattmeters are provided in the set. One model set of this type was made in the VNII Laboratory of the Commit tee and is at present being used.

Tests have shown that the voltage in the secondary circuit of the phase shifter changes by less than 1% when the rotor is moved through 120~ the shape of the current and voltage are practically sinusoidal; the adjustments of the phased voltage and current are independent of each other and provide an easy setting of the standard watt- meter at any point on the scale.

Experience gained in operating the set has shown that it is convenient and fully satisfies its design require-

ments.

Conclusions. This portable set may find a wide application both in State Inspection Laboratories for Measuring Equipment and in establishments connected with the testing and repair of electricity meters, in parti- cular in Base Laboratories for Departmental Inspection. It is therefore advisable to organize mass production of

these sets.

AN E L E C T R O N I C PHASE METER FOR SUPPLY FREQUENCY C I R C U I T S

I . M. V i s h e n c h u k , A. F. K o t i u k a n d V. A. S h e r e m e t ' e v

In many investigations of transients in supply frequency circuits it is required to know the phase shift between two voltages.

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