The problems involved in developing and using a system for monitoring the quality of electric power in an

underground mine from the yield of diamond-containing rocks are considered. The equipment of such

mining enterprises that gives rise to electromagnetic interference and has an undesirable effect on the

quality of the electric power is determined. The results of measurements obtained using this monitoring

system are analyzed.

Keywords: mining industry, underground mine, monitoring system, electric power quality, electromagnetic

compatibility.

For the effective utilization of electric power, it is important to analyze the electric power consumed and to set up a

system for controlling its quality. The results of the operation of such a system considerably influence the investment programs

of companies and enterprises. This is an important stage of the control if the values of the existing electric power quality do

not correspond to its standard values [1–5].

The parameters of the electric power which it is advisable to monitor for the best results in controlling the quality

are determined for each enterprise. To do this, investigations need to be carried out to determine the locations where mea-

suring instruments need to be placed to measure the quality, and for the continuous monitoring and analysis of the results

obtained during the monitoring. These problems are solved by the combined work of specialists in industrial power services

and scientific-research teams.

At present, the monitoring of electric power quality at enterprises is of a short-term periodic nature. It is only car-

ried out for certification, periodic and some other forms of tests to confirm that they correspond to obligatory requirements.

The results of short-term tests do not fully or reliably reflect the situation in this area [6, 7].

For the continuous monitoring of the quality control of electric power, prolonged tests of some of its characteristics

are required. This primarily relates to the parameters of surges and dips in the voltage. Measurement data characterizing these

dynamic processes and their statistical processing must be stored for a year. Only when this requirement is satisfied can the

statistical characteristics obtained be used to improve and develop contractual arrangements between the suppliers and con-

sumers of electric power.

To increase the reliability, for completeness of the results, and for the operational control of electric power quality,

the monitoring must be continuous. It is therefore necessary to carry out constant monitoring of the quality, using an auto-

mated data-measuring system for monitoring electric power quality. Such a system enables measurement data to be obtained

for determining that the electric power meets the compulsory requirements and makes clear the sources and reasons for any

degradation in quality. A complete description of the operation of the data-measuring system can be found in [8–12].

Measurement Techniques, Vol. 57, No. 4, July, 2014

AN ANALYSIS OF THE RESULTS OF MONITORING

THE QUALITY OF ELECTRIC POWER IN AN

UNDERGROUND MINE

ELECTROMAGNETIC MEASUREMENTS

A. S. Semenov and N. M. Kuznetsov UDC 621.314

Politechnic Institute, Branch of the Ammosov North-Eastern Federal University, Mirnyi, Russia; e-mail: sash-alex@yandex.ru. Translatedfrom Izmeritel’naya Tekhnika, No. 4, pp. 31–34, April, 2014. Original article submitted September 2, 2013.

0543-1972/14/5704-0417 ©2014 Springer Science+Business Media New York 417

The system contains the following: measuring voltage transformers, measuring current transformers, measuring-

computational systems, i.e., instruments for measuring the quality of the electric power, software-hardware systems for mon-

itoring the quality of the electric power, communication lines between the measuring transformers and the instruments for

measuring the electric power quality, modems, Ethernet apparatus and networks, concentrators, data servers, data acquisition

stations, and working stations with standard system and applied software.

To measure the quality of the electric power in underground mine equipment, we used the skip lifting equipment of

the skip shaft and the ball mill of part of the technological riveting system. The following features were measured: the rms

voltage and the fundamental-frequency voltage, the steady deviation of the voltage, the frequency, the voltage asymmetry

coefficient for the reverse and zero sequences, distortions of the sinusoidal shape of the voltage curve, the nth harmonic com-

ponent of the voltage, any intermittent surge, the frequency deviation, the duration of a voltage dip, the depth of a voltage

dip, the amplitudes of a voltage change, short-term and prolonged flicker, the phase shift between phase voltages at the fun-

damental frequency, and the active, reactive and total power.

We used a three-phase four-conductor system for measurements, since this corresponded most closely to the cir-

cuits for connecting the current and voltage transformers employed. In Resurs-UF2 analyzers, in addition to those employed,

the following versions of the measuring circuits were provided: a three-phase three-conductor circuit with voltage and current

transformers, a three-phase four-conductor circuit for direct measurement of the voltage and current, a three-phase three-con-

ductor circuit with two voltage and current transformers, and a single-phase measuring circuit with a single current transformer.

Combined connection of the measuring instrument and the meter for the electric power was also provided.

Measurements were made at intervals of 1 sec, and they were of very high volume. To average the daily graphs with

a measuring interval of 1 min, we used the Resurs UF2Plus software for processing and analyzing the results. Graphs of the

measured and processed values of the electric power quality on the skip underground equipment of the skip shaft of the under-

ground mine are described in [13]. In Figs. 1 and 2, we show graphs of the voltage deviation and the coefficients of the har-

monic components.

We can draw the following conclusions from an analysis of the results of the measurements. The deviations of the

phase and interphase voltages (see Fig. 1) exceed the permissible value by 5%, but by not more than the critical value, which

is equal to 10% of the nominal value, the frequency deviations are within the standard limits and do not exceed the permis-

sible values of 0.2 Hz, the power factor of the equipment does not fall below 0.8, which is an acceptable value, the sinu-

soidality distortion coefficients of the phase and interphase voltages is a little greater than 3% and, hence, lie in the range of

permissible values, the coefficients of the 23rd and 25th harmonic components (see Fig. 2) exceed the limit permissible val-

ues, which are equal to 1.5%, by 0.75 and 0.35%, respectively, and amount to 2.25 and 1.85%, which is greater than the nom-

inal permissible value, which is 1%, by a factor of 2.25 and 1.85, respectively, the coefficients of the 35th and 37th harmonic

418

Fig. 1. Graphs of the voltage deviation: 1, 2, 3) deviations for the A, B, and C phases, respectively.

components exceed the limit permissible values, equal to 1.15 and 1.10%, by 0.8 and 0.65%, respectively, and amount to 1.95

and 1.75%, which exceeds the nominal permissible value, which is equal to 0.75%, by a factor of 2.6 and 2.3, respectively,

the current and voltage signals for voltage drops and voltage surges have an extremely distorted sinusoidal form, which is

caused by unstable operation of the electrical equipment under these operating conditions.

We can draw the following conclusions from a comparison of the results of measurements of the electric power

quality obtained from measurements on the equipment used in the underground mine from the yield of diamond-containing

rocks: on the skip lifting equipment we observed sections of voltage surges sometimes exceeding 10% of the nominal value

in phase B, whereas on the other equipment we observed a drop in voltage, approximating to 9% of the nominal value of

phase C. These features are due to the fact that the ball mill is situated much further from the transformer substation than

the skip machine and the inaccurate choice of the section of the feeder cable; on the skip underground equipment, unlike

the ball mill, we observed higher deviations of the nth harmonic components, in particular the 23rd, 25th, 35th, and 37th

components, which is due to the type of electric drive employed by the skip lifting equipment (a dc motor with a high-power

converter, having a 12-pulse rectification circuit) [14], whereas on the ball mill an induction motor with direct startup is

used as the electric drive.

Conclusions. The system for monitoring the quality of electric power enables one, with continuous monitoring, to

reveal problem sections and equipment in the mining industry. After processing and analyzing the measurement data, one can

determine the reasons for any deterioration in the quality of the electric power, and then make recommendations for appro-

priate power services to eliminate any deficiencies.

In the underground mine considered, which extracts diamond-containing rocks for skip underground equipment,

when a voltage surge exceeds 10% of the nominal value, we recommend the inclusion of surge limiters in the transformer

network, supplying the electric drive of the skip machine, while, to reduce the deviation of the harmonic components, we rec-

ommend the introduction of active higher-harmonic filters instead of the passive filter-compensating devices used at the pre-

sent time [15]. For the ball mill, we propose conversion of the section of the cable feeding its cell, and if this value turns out

to be less than the set value, we recommend replacement of the cable in order to match the voltage to the nominal value [16].

This research was carried out in the framework of the Project on Development of a Mathematical Model for

Estimating the Effect of the Operation of Electrical Equipment on the Quality of the Electric Power, developed with the sup-

port of a grant from the rector of the North-Eastern Federal University for students and young scientists in 2013.

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419

K, %

n

Fig. 2. Coefficients of the nth harmonic components of the voltage: 1) nominally permissible value;

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