CALCULATION OF THE ECONOMIC EFFICIENCY OF IMPLEMENTING THE AZAT-2 AUTOMATED CHARGING UNIT

G. G. OKUNEV, A. V. KOBZEV

(Presented by the Scientific and Technical Seminar of the Department of Static Converters of the Research Institute of AEM at TPI)

The AZAT-2 automated two-channel charging unit was developed and manufactured by the Tomsk Scientific Research Institute of Automation and Electromechanics under a contract and technical assignment from the motor-transport enterprise of the Kemerovostroitrans trust. It is intended specifically for automating the processes of charging storage batteries of various types and brands of motor vehicles [6]. The new charging unit provides a more advanced technological process for charging batteries with two-stage stabilized currents and has better technical and economic characteristics in comparison with the VSA-5 charging installations operating at the motor-transport enterprise. With the new technology for charging storage batteries on the AZAT-2, the following is achieved:

1. A reduction in the cycle (basic duration) of battery charging by 2.34 hours, or by 27%.
2. A substantial reduction in labor intensity, which allows the motor-transport enterprise to reduce the number of battery attendants by 26–27%.
3. Savings in consumed electrical energy.
4. It greatly facilitates the physical labor of battery attendants.

In addition, it is known from the literature that charging carried out with a two-stage stabilized current promotes good formation of the plates and increases the service life of storage batteries by 30–33% [2, 3].

The additional capital investments associated with the introduction of AZAT-2 are recouped by the savings obtained in operating costs in only one month.

In this calculation, the existing VSA-5 charging installations (rectifiers) in operation at the motor-transport enterprise are taken as the basis for comparison of the variants [5, p. 4].

The calculation of charging cycles and of the standardized number of storage-battery charges per year for the variants being compared is characterized by the data of Table 1 [6].

Calculation of the Basic Labor Intensity and the Number of Battery Attendants for the Motor-Transport Enterprise

The labor-intensity standards by types of technical maintenance and current repair of the rolling stock of motor transport are characterized by the following indicators from [5] (Table 2):

Table 1

1. By the total labor input for technical servicing and current repair of motor transport

\[ \Sigma T_{\text{n}} = \Sigma t_{\text{TO-1}} + \Sigma t_{\text{TO-2}} + \Sigma t_{\text{tr}}, \tag{1} \]

where

\[ \Sigma t_{\text{TO-1}} \]
— total labor input for the first technical servicing, in standard-hours;

\[ \Sigma t_{\text{TO-2}} \]
— total labor input for the second technical servicing, in standard-hours;

\[ \Sigma t_{\text{t-r}} \]
— total labor input for current repair of the rolling stock of motor transport, in standard-hours.

Table 2

Table 3

Standards of specific labor input and the total labor input for technical maintenance and current repair of storage batteries are characterized by the indicators in Table 3 [5].

1. By the specific total labor input for technical maintenance and current repair of storage batteries,

\[ \Sigma t_{\text{acc}}=\frac{\Sigma t_{\text{TO-1}}}{100}\,n_1+\frac{\Sigma t_{\text{TO-2}}}{100}\,n_2+\frac{\Sigma t_{\text{c.r.}}}{100}\,n_3, \tag{2} \]

where

\(n_1, n_2\) and \(n_3\) are the time standard, in %, for maintenance and repair of storage batteries as a share of the total labor input of planned TO-1, TO-2, and current-repair work.

To determine the number of battery attendants, we calculate the average labor input, consisting of the standard costs for servicing and repairing batteries for 4 groups of motor vehicles (Table 3), which is represented by the following indicators:

a) \(24.0+21.63+17.63=62.26\) man-hours; average labor input \(62.26:3=20.75\) man-hours;

b) \(23.7+19.8+15.9=59.4\) man-hours; average labor input \(59.4:3=19.8\) man-hours;

c) \(27.92=25.05+22.89+75.86\) man-hours; average labor input \(75.86:3=25.28\) man-hours;

d) \(41.76+38.0+32.63=112.40\) man-hours; average labor input \(112.40:3=37.46\) man-hours.

For the motor-vehicle enterprise as a whole, the average annual labor input is

\((20.75+19.8+25.28+37.46):4=25.82\) man-hours for the entire vehicle fleet \((25.82\ \text{man-hours}\cdot 690\ \text{vehicles})=17816\) man-hours. The annual working-time fund of one battery attendant is 1780 hours. Based on the labor input and the working-time fund, the number of battery attendants at the motor-vehicle enterprise is:

\[ 17816:1780=10\ \text{persons}. \]

With the introduction of AZAT-2 and the use of the new technology for charging storage batteries with two-stage stabilized currents, the charging cycle (duration in hours) was reduced by 2.34 hours, or by 27%, and the labor input of the battery attendants at the motor-vehicle enterprise decreased by

\[ 17816\cdot 0.27\% = 4810\ \text{man-hours}, \]

which, with an annual working-time fund of 1780 hours, releases three battery attendants. This yields savings in the wage fund:

\[ E_{\text{w}}=r_{t.c}\cdot t_r\cdot P_r\cdot K\cdot D\cdot O =0.474\cdot 4810\cdot 1.25\cdot 1.15\cdot 1.07 =3769\ \text{rubles}, \]

where \(r_{t.c}\) is the hourly tariff rate of battery attendants, in kopecks;

\(t_r\) is the labor input in man-hours;

\(P_r\) is bonuses under the time-bonus wage system;

\(K\) is the district coefficient, in %, applied to the basic wage and bonus amounts;

\(D\) is the amount of additional wages;

\(O\) is deductions to special-insurance agencies.

Calculation of Electricity Costs by Variant

The installed power of one basic VSA-5 unit is 1.5 kW. Converted to the level of the production capacity of the new AZAT-2 charging unit, the motor-vehicle enterprise will need to have 6 instal-

of VSA-5 units (Table 1), whose installed capacity will be 9 kW. The electricity costs for six VSA-5 units will be:

\[ 9\ \text{kW}\cdot 255\ \text{days}\cdot 24\ \text{h}\cdot 0.8\cdot 0.014 = 617\ \text{rubles}. \]

The installed capacity of the new charging unit is 4 kW, and the annual electricity costs will be:

\[ 4\ \text{kW}\cdot 255\ \text{days}\cdot 24\ \text{h}\cdot 0.8\cdot 0.014 = 274\ \text{rubles}. \]

Electricity savings:

\[ E_{\text{el}} = 617\ \text{rubles} - 274\ \text{rubles} = 343\ \text{rubles}. \]

Calculation of Savings from Increasing the Service Life of Storage Batteries

It is known from domestic and foreign (U.S.) literature that fast-acting automatic charging units that charge storage batteries with two-stage constant stabilized currents ensure good formation of the plates and increase the service life of storage batteries by 30–33% [2, 3]. If it is assumed that, on average, the service life of storage batteries will increase by 25–30%, then the resulting savings for the motor-transport enterprise will also be considerable. The average service life of storage batteries when charged on the existing charging installations is 20 months (according to [6], 18–24 months). With the new charging technology the service life will be

\[ 20\cdot 1.3 = 26\ \text{months}. \]

The average cost of storage batteries in the existing motor-vehicle fleet is:

\[ \begin{aligned} &6\text{-ST-}128 — 40\ \text{rubles}.\\ &3\text{-ST-}98 — 14.90\ \text{rubles}.\\ &3\text{-ST-}98\text{PD} — 18.15\ \text{rubles}.\\ &3\text{-ST-}84 — 14.20\ \text{rubles}.\\ &3\text{-ST-}70 — 11.80\ \text{rubles}. \end{aligned} \]

Total:

\[ 99\ \text{rubles} : 5 = 19\ \text{rubles}\ 80\ \text{kopecks}. \]

The cost of batteries (based on service life) per one month of operation:

a) when charged on VSA-5:

\[ (19.8\ \text{rubles} : 20\ \text{months}) = 0.99\ \text{rubles}; \]

b) when charged on AZAT-2:

\[ (19.8\ \text{rubles} : 26\ \text{months}) = 0.77\ \text{rubles}. \]

Monthly saving per battery:

\[ 0.99 - 0.77 = 0.22\ \text{rubles}; \]

for the entire fleet per year:

\[ E_{\text{sl}} = 0.22\cdot 12\cdot 1890\ \text{motor vehicles} = 4990\ \text{rubles}. \]

The total saving is:

\[ E = E_{\text{el}} + E_{\text{zp}} + E_{\text{sl}} = 3769 + 343 + 4990 = 9102\ \text{rubles}. \]

The introduction of the automated charging unit will require additional capital investments in the motor-transport enterprise. The total cost of six basic VSA-5 installations is:

\[ 80\cdot 6 = 480\ \text{rubles}. \]

The full cost of AZAT-2 under the conditions of mass production by the plant is 1068 rubles. Additional capital investments, excluding the cost of the replaced old installations, will be:

\[ K_{\text{n}}1068\ \text{rubles} - K_{\text{s}}480\ \text{rubles} = \Delta K588\ \text{rubles}, \]

where

\[ \begin{aligned} K_{\text{n}} &— \text{new capital investments};\\ K_{\text{s}} &— \text{old capital investments};\\ \Delta K &— \text{amount of additional capital investments}. \end{aligned} \]

The payback period due to savings in operating expenses is:

\[ 588\ \text{rubles} : 9102\ \text{rubles} = 0.065\ \text{year}, \]

or 24 calendar days. Coefficient

efficiency: 9102 rubles : 588 = 1550%, or each ruble invested yields a return of 15 rubles 50 kopecks per year.

Automated two-channel charging units, possessing high productivity and cost-effectiveness, will undoubtedly find wide application in large motor-vehicle enterprises of categories I and II. In medium and small motor-vehicle enterprises (categories III, IV, and V) with a small number of vehicles, where full utilization of two-channel charging units will not be ensured, it is advisable to use single-channel AZAT-1 charging units, also developed at the Research Institute of AEM under TPI. The calculations performed have shown the great economic expediency of creating centralized or district charging stations to serve several small and medium motor-vehicle enterprises. At such stations the charging units will be used more rationally and with the smallest staff of battery attendants.

The first prototypes of the AZAT-2 charging units (1) have successfully passed tests. Their design, electrical, and technical characteristics meet modern requirements, and a large number of requests have been received for the manufacture of these units.

The existing demand for AZAT-2 and AZAT-1 can be met by organizing serial production of charging units at one of the plants of the Ministry of the Electrical-Engineering Industry; the wide introduction of the devices will give motor-transport operators an economic effect amounting, across the country, to millions of rubles per year.

REFERENCES

1. Basic methodological provisions for determining the economic efficiency of research work, developed by the State Committee for the Coordination of Scientific Research of the USSR, 1964.

2. Methodology for determining the annual economic effect obtained as a result of the introduction of new technology, approved by the State Scientific and Technical Committee of the Council of Ministers of the USSR, 1961.

3. Bulletin of Foreign Technical Information of TASS, No. 37 (1935), 1969.

4. I. A. Aguf. Work of the Third International Symposium on Storage Batteries. “Nauka,” 1963.

5. Regulations on the technical maintenance and repair of rolling stock of motor transport, approved by the State Committee for Automation and Machine Building under Gosplan of the USSR and by the Ministry of Motor Transport and Highways, 1965.

6. Rules for the operation and care of automobile lead-acid batteries, developed by the manufacturing plants, 1967.

7. V. P. Obrusnik, A. V. Kobzev, V. G. Kiselev, S. K. Zeman. Automated AZAT-2 unit for charging automobile storage batteries. Izvestiya TPI, vol. 243. TTU Publishing House, 1970.