# 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
In the course of the experiment, the software of the computing unit runs the  
Figure 3: Block diagram (**a**) and general view (**b**) of the VATUR unit. initial processing of instantaneous values and the calculation of quantitative indicators of the combine's operation. The following parameters of the controlled electric actuators of the combine are calculated:  
* effective current
* effective value of phase voltage
* effective and apparent power
* power factor  
The displacement sensor was used to control the combine's feeding speed to the mining face. The obtained parameter values are recorded in the non-volatile memory of the \"VATUR\" complex. Specialised PC-VATUR software installed on a personal computer helps with further processing and analysis of the data array [11]. Experimental studies for assessment of the performance of mining machines in the conditions of potash mines were carried out on the Ural-20R-11 combine at the Verkhnekamskoye potassium-magnesium salt deposit. The combine was developing the Krasnyi-II seam; the seam bedding angle during the study period was \(-5^{\circ}+1^{\circ}\). The design features of Ural-20R-11 heading-and-winning machines and the technology of their use together with the equipment of the mining sets determine the magnitude and nature of the load change in the actuators of executive units [28; 29; 30]. Figure 4 shows the change curves of effective drive power of the executive units for the Ural-20R combine operating in the stope. Using the load curves, it is possible to single out the intervals of actuator operation in various modes: T1 when the engines off, T2 when the engines are starting, T3 for the transient mode, T4 for steady-state operation, T5 for no-load operation of the combine. Figure 4: Changing energy parameters of the actuators operating in the Ural-20R combine: U1—input phase voltage, V; N1—active power of the cutting disc drive, kW; N2—active power of the fender drive, kW; N3—active power of the portable motion drive, kW; T1—the duration of the “off” state of the combine’s electric motors, s; T2—duration of motors’ start, s; T3—hewing duration, s; T4—duration of steady-state operation mode, s; T5—duration of no-load operation mode, s.  
The total time of the productive work of the combine \(\Sigma T_{p.t. }\), time spent on auxiliary operations \(\Sigma T_{t.t. }\) and technological breaks \(\Sigma T_{t.t. }\) are determined by the load curves of the combine actuators in accordance with the expressions:  
\[\Sigma T_{p.t.}=\Sigma T3+\Sigma T4;\,\Sigma T_{t.t.}=\Sigma T2+\Sigma T5;\, \Sigma T_{t.t.}=\Sigma T1. \tag{8}\]  
The actual data obtained by recording the operating parameters of the electric actuators of the Ural-20R-11 were used to determine the component periods of the mining machine's operation. The duration of the analysed time interval was 26 days. The productivity time of the heading-and-winning combine is determined by the periods of operation of the drag-bar conveyer-reloader, which provides for loading the freed ore from the working area. By correlating the obtained values with the total time of use of the combine (minus the time for scheduled maintenance \(\Sigma T_{s.m}\) and unscheduled repairs \(\Sigma T_{u.r}\)), the values of the productivity coefficients for each day were determined (Figure 5)  
The average value of the productivity coefficient for the entire analysed time period was \(k_{p.r.}=0.29\). The authors analysed the recorded data about the load of the electric actuators of the Ural-20R-11 combine and determined the total time for performing individual technological operations. During the considered time period, the combine was mining ore using the technology of two-layered mining of chambers. This technology includes the sequential execution of the following operations:  
1. \"Hewing\", defined as a preparatory operation, where the combine moves from the gateway into the stop;
2. \"Full-face mining\", defined as productive work of the combine using a full section of the final element;
3.