SU106964A1 - Device for direct measurement of power and operation of engines and other machines - Google Patents

Description

The subject matter of the invention is a device for directly measuring the power and operation of engines and other machines, consisting of a shunt current mashina connected to the shaft of the motor under test, and a torque meter with electrical sensors.

A feature of the proposed device for direct measurement of mechanical power and operation is the use of a DC voltmeter, calibrated directly in units of power measurement, and a DC motor connected to a counting mechanism of a conventional electrical energy meter for measuring operation.

The electromotive force of a shunt electric motor (tachodynamo) (see drawing) is directly proportional to (in an unsaturated state) the rotational speed of the core, and the variable component of the field current / electric armature anchor associated with the corresponding rotating element of the engine under test or Maschiny, gains momentum n, proportional to the speed of rotation (displacement) and,.

The variable component of the excitation current, ", obtained from the electric sensor, is proportional to the force P or the moment M applied on the shaft of the maschine or node under test.

Depending on the type of sensor and the power source is selected.

To compensate for the residual magnetic flux of the DC mash, a battery B was used, supplying the winding // - //. The latter is included in the counter winding of / - / and is not more than 5% of it (in terms of ampere turns).

It is known that an electromotive force developed in the crust of a shunt mask with independent excitation is equal to

№ 106964

  SF, / g + C1 / A, where; C and Ci are the proportionality coefficients;

Fo is the residual magnetic flux of the machine; ,, ;. ig is the drive current; n., - the number of revolutions of the machine. As it can be seen from the diagram, the number of revolutions of the core where: ““ is the number of revolutions of the core;

K - coefficient of proportionality (depending on the gear ratio);

17, (- the speed of movement (rotation) of the tested machine or unit.

The variable component of the excitation current, i.e. KiK2P or,

where: Ki, KZ are the proportionality coefficients (depending on the "sensor");

P is the mechanical force acting on the shaft or assembly; M - the moment developed or applied to the shaft. Consequently, the emf is developed in the machine cortex,

.KsPU ,, CR, „

KZ is the proportionality coefficient (depends on the electric machine).

K-KiKzKs

In other words, electromotive force, developed by an electric machine, is proportional to the mechanical power of PU.

A conventional magnetoelectric or electromagnetic voltmeter 2, connected to the terminals of the core, gives indications of proportional mechanical power and, therefore, can be calibrated directly in units of its measurement. As is known, these devices (magnetoelectric and electromagnetic systems) can be of fairly high accuracy classes - 0.2 and 0.5.

By connecting a core to the same terminals (parallel to the voltmeter, or rather, PU), a 10-watt 3-DC motor connected to a counting mechanism from an ordinary electric energy meter causes it to rotate at a speed proportional to E or the same most, PU. Readings of the counting mechanism where: L is the number of revolutions of the counting mechanism;

C is the proportionality coefficient depending on the gear ratio of the counting mechanism;

PU is mechanical power; t - time

The braking torque of the counting device is the same as that of a conventional electricity meter. Such a counting device counts the work done.

Subject invention

Claims (2)

1. A device for direct measurement of power and operation of engines and other machines, comprising mechanically connected to the shaft of the machine a tacha-dynamo and torque meter with electrical sensors, characterized in that, in order to improve the design and increase reliability, to measure the mechanical power A DC voltmeter connected to the tachodynamo brushes is applied, indicating a voltage proportional to / "-BUT- ," , measured power, and a DC collector motor connected to the counting mechanism of a conventional electricity meter and connected to brushes of the same tahodamo is used to measure the work. 2. The device according to claim 1, characterized in that, in order to eliminate the error introduced by the tahodynamo as a result of the residual magnetization of its stator, a compensation voltage is applied to the additional stator winding.