SU1302221A1 - Method of determining incremental load losses of d.c.electric machine - Google Patents

Abstract

The invention relates to electrical engineering and can be used in tests and studies of direct current electric machines. The purpose of the invention is to improve the accuracy of a constant volume while reducing labor intensity and energy consumption. The anchor chain of the electric machine under test consists of the winding of the core 1, the winding 2 of the additional poles, the compensation winding 3, the working brushes 4, the excitation winding 5 connected to the direct current source. After a small amount of current is established in the winding 5, the voltage is applied to the core circuit and, by gradually increasing the current, the test machine is driven into rotation. Then, by jointly adjusting the excitation current within the limits of not more than 0.1-1.5% of the nominal and current of the core circuit, the specified work on the rotation frequency and load current is provided for a sharp work. When the operating temperature of the windings is reached, the total losses directly at the collector are measured by measuring the load current with an ammeter 7 and voltage with a voltmeter 8 and measuring brushes 9. Reducing the number of measurements reduces the error. 1 il. S & (L co oo yu

Description

The invention relates to electrical engineering and can be used in tests and studies of direct current electric machines.

The purpose of the invention is to increase accuracy while reducing labor intensity and energy consumption.

The drawing shows a diagram of the device for implementing the method.

The method for determining the loading additional losses is carried out as follows.

15

The anchor circuit of the electric machine under test, consisting of the winding of the core 1, the winding 2 of the additional poles, the compensation winding 3, the working brushes 4, and the excitation winding 5, when it is independently turned on, is connected to its direct current source. After applying voltage to the winding 5 of the excitation and the establishment of a small value

The technical and economic effect of the method as compared with the known one is as follows. According to the proposed method, only a test machine is required to determine the NDP, which, during the test, operates in the engine mode without mechanical load on the shaft. However, despite the absence of an engine on the shaft, the method makes it possible to load the crown chain at. rotation of the engine idle current of any size, t, e. Such a mode of operation can easily be stoked from the load current and rotational frequency, with which it is necessary to determine the load additional losses. This is ensured by connecting the cable

the current in this winding is supplied from the voltage of the excitation winding to the individual sources of direct current and through the windings of the core, additional poles and compensatory winding of the current lying in the operating value range, and the current in the excitation winding not exceeding 0.1-1, 5 from the nominal value. In this way, the test scheme is simplified and the NDP determination accuracy is achieved, which is explained, firstly, by reducing the number of measurements made to determine the sum of losses and main losses, since all measurements are carried out only on the subject

on the root chain. By gradually increasing the current in the crustal circuit, the machine is rotated. Then, by jointly adjusting the excitation current within not more than 0.1-0.5% of the nominal value, which is monitored by the indication of ammeter 6, and the current of the crustal circuit rotational frequencies and load currents. After a time sufficient to reach the operating temperature of the windings, the total losses ZP directly at the collector of the electric machine under test are measured as the product of the load current measured by ammeter 7 and the voltage measured at the collector with a voltmeter 8 and measuring brushes 9, insulated from the working brushes 4. Then the electric machine is stopped, the main losses P in the copper of the winding core 1 are determined for a given load current. Since the excitation current is insignificant, the magnetic losses are ins are negligible and neglected, and load additional losses obtained from the expression

ZP - P „

R,

m "x

- mechanical losses of the tested machine, previously measured at different frequencies of rotation.

Similar examples of load additional losses are carried out at other modes of operation, determined by different ratios of load current and rotation frequency.

The technical and economic effect of the proposed method as compared with the known one is as follows. According to the proposed method, only one test machine is required to determine the NDP, which, during the tests, works as a motor without mechanical load on the shaft. However, despite the absence of an engine on the shaft, the method allows to load the crown chain at. rotation of the engine idle current of any size, t, e. can easily provide such a mode of operation according to the load current and rotational speed, at which it is required to determine the load additional losses. This is ensured by connecting the core circuit of the motor winding to 30

individual direct current sources and transmissions on the windings of the core, additional poles and the compensation winding of a current lying in the range of operating quantities and a current in the excitation winding not exceeding 0.1-1.5% of the nominal value. Thus, the test scheme is simplified and the NDP determination accuracy is improved, which is explained, first, by decreasing the number of measurements made to determine the sum of losses and main losses, since all measurements are carried out only on the subject.

motor, and, secondly, there is no need to measure the main loss in copper of the windings of the additional poles and compensatory and brush contact.

Reducing the number of measurements reduces the error, increases accuracy and reduces the complexity of the test.

Operating the engine without a load on the shaft, using only two energy sources, one of which is designed to power the excitation winding and works practically in idle mode, the absence of magnetic losses in the engine from the main pole floor significantly reduces the power consumed from the network.

There is also no need for additional equipment.

nor (calibrated drive motor, special stand), which not only reduces the cost of testing, but also reduces labor intensity, since it is not necessary to press the coupling halves on the shafts of electric machines, to combine, install and fix the machines on the stand.

In the known technical solution of the test, the electric machine operates with a generator in the short-circuit mode and is driven in rotation by a calibrated motor. In this case, it is required to carry out a large number of measurements and calculations to determine the input power, the total loss of a calibrated engine, the main losses of the test machine, including mechanical losses, copper losses of the core windings, additional pole windings and a compensation winding, losses in the brush contact and connecting cables that form a short-circuited. In order to process the test results, it is necessary to have previously removed the dependence of the losses of the idle drive motor on the excitation current and the dependence of the mechanical losses articulated between the test machine and the sorted engine. Conducting an experiment requires a large

Editor N. Tupitsa Order 1214/45

Compiled by V.Nikanorov

Tehred L. Serdyukova Proofreader A.Ilin

Circulation 731 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

50

0

five

accuracy, however, its accuracy is relatively low, which is explained by the accumulation of error with a large number of measurements, as well as by the fact that the load additional losses are defined as the difference of large and similar values.

Claims (1)

Invention Formula The method of determining the additional load losses of an electric machine of direct current by determining the sum of the total losses and the subsequent elimination from it of the main losses of the electric machine, characterized in that, in order to improve accuracy while reducing the labor intensity and energy consumption, the electric machine is used in the engine mode without load on the shaft, the nominal mode of the current of the core and the frequency of rotation is set by adjusting the current of the main circuit and the excitation current, and the magnitude of the excitation current does not exceed 1 , 5% of the nominal value, and then the voltage on the collector is measured with the help of additionally installed brushes and the current in the core circuit and the total losses are determined from them.