# Performance Evaluation of Heading-and-Winning Machines in the Conditions of Potash Mines
## 2 Performance Evaluation Procedures for Heading-and-Winning Machines in Potash Mines
Let us set the range of possible values of complex performance indicators by the coordinate plane, where the ordinate describes the values of the energy efficiency coefficient, and the abscissa shows the productivity coefficient (Figure 2). Let us take the conditional values of the coefficients \(k_{p.r.u. }\) and \(k_{e.ef.u. }\) and divide the coordinate plane into four zones. Conditional values \(k_{p.r.u. }\) and \(k_{e.ef.u. }\) can be determined, respectively, as the average values of performance coefficients \(k_{p.r. }\) and energy efficiency \(k_{e.ef. }\) of the operation of the combine miners (plant, enterprise), the work of which is analyzed in a given period of time. Reasonable correction of national values \(k_{p.r.u}\) and \(k_{e.ef.u}\) is possible based on technical and economic feasibility. If the values of the efficiency indicators are in Zone 1, the work of the combine can be described as ineffective. The low value of the productivity coefficient determines the poor organisation of works in the stope: The period of the combine's productive work is much shorter than the routine breaks. Low values of the energy efficiency factor determine high specific energy consumption for separating the ore from the potash massif, which, when the combine is operating at full capacity, is a consequence of low productivity and is accompanied by a high content of small non-processing grades in the mined ore. Zone 2 depicts high productivity factor but low energy efficiency values. The specified combination of efficiency indicators is typical when the unit executes undercutting of the seam (the operation uses a partial section of the final element), or in the case of a continuing limitation of the combine's feeding speed to the face, when the operator is focused on the operation of a self-propelled car. Figure 2: Zones for possible values of \(k_{p.r.u. }\) and \(k_{e.ef.u. }\) coefficients. The high technical level of the use of heading-and-winning machines with poorly organised stope mining operations is involved in the coefficients located in Zone 3. For example, lower productivity of self-propelled cars due to the mining of remote chambers would mean longer distances for delivering the mined ore and therefore higher idling time for the combines. This feature is typical for a chamber system for the development of layers of potash ores and is a common reason for a decrease in the actual values of the performance coefficient of combines. According to the authors, the value \(k_{p,p}=0.5\dots\ 0.6\) should be considered satisfactory. High productivity of ore delivery vehicles in stope and stability of the potash ore mining process provide for high values of coefficients of energy efficiency \(k_{e,ef}\) and productivity \(k_{p,r}\). (Zone 4) [7]. Verification of the proposed methodological approaches and theoretical conclusions was carried out during experimental studies in the conditions of potash mines. Experimental Studies for Evaluating the Performance of Heading-and-Winning Machines in Potash Mines  
VATUR, a portable instrumentation unit, was developed and made for experimental research in potash mines. It is designed to measure and register voltages, currents, effective and apparent powers of the combine's electric actuators, tilt angles and the distance traveled by the combine. VATUR is used as a system for mobile measurement and computation; it consists of several blocks and is installed in the explosion-proof magnetic station of the combine. The portable system (Figure 3) includes a power supply unit, a computing unit, voltage dividers and sensors for current and displacement. The VATUR unit records the electrical parameters of the combine's actuators using two voltage inputs. Each input is designed to control the loads of three electricity consumers. The effective power in a three-phase circuit is measured by the method of one wattmeter with a dummy zero. The device records 100 measurements in a single period of the supply voltage fluctuation cycle.