4. Development of method to improve efficiency of residual current device under 1000 V on excavators of mining enterprises

neutral under 1000 V at normal operating conditions of the electrical network of

Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage…

The developed methodic is based on the method of determining the parameters in the short network with isolated neutral. The method consists of measuring the modulus of linear voltage, phase voltage in respect to earth after the connection between phase and earth the auxiliary conductance. From the measured values of the modulus of linear stress, voltage to earth after the connection between phase and earth the auxiliary conductance, bear the auxiliary conductance in mind, admittance, conductance, and capacitive susceptance of phase-to-ground are deter-

According to the measured values of the modulus of linear voltage, Ul, phase voltage in respect to earth, Uphо, when connecting auxiliary conductance, go, is determined admittance, conductance and capacitive susceptance of isolation by

> <sup>y</sup> <sup>¼</sup> <sup>1</sup>:73Upho U<sup>l</sup> � 1:73Upho

� <sup>3</sup>U<sup>2</sup>

!

<sup>b</sup> <sup>¼</sup> <sup>y</sup><sup>2</sup> � <sup>g</sup><sup>2</sup> � �<sup>0</sup>:<sup>5</sup>

Based on the results of the determination of admittance, conductance, and capacitive susceptance of isolation in a short line 0.4 kV on the excavator EKG-8I in the coal mine Ekibastuz, Angrensor LLP, the results were processed by using the small sample method. The results from the experimental research regarding the parameters of the insulation as well as an assessment of the results collected using

Studying the isolation of electric networks under 1000 V of the excavator showed that the insulation resistance is due to active resistance which characterizes the properties of the dielectric of insulating material used for insulation of live parts

Parameters of the insulation The number of measurements X mean value of

The results of determination of the parameters of the insulation in a short line 0.4 kV on excavator EKG-8I in

parameters <sup>12345678</sup>

2.20 2.21 2.18 2.24 2.17 2.22 2.15 2.17 2.19

1.34 1.35 1.37 1.40 1.39 1.41 1.35 1.37 1.37

1.74 1.75 1.69 1.75 1.67 1.71 1.67 1.68 1.71

pho Ul � <sup>1</sup>:73Upho � �<sup>2</sup> � <sup>1</sup>

go, (24)

: (26)

0:5go, (25)

excavators with operating electrical receivers [8].

DOI: http://dx.doi.org/10.5772/intechopen.81384

mined with satisfactory accuracy [6, 36].

mathematical dependences [37]:

• admittance of isolation

• conductance of isolation

<sup>g</sup> <sup>¼</sup> <sup>3</sup>U<sup>2</sup>

• capacitive susceptance of isolation

the small sample method are shown in Table 1.

Admittance of isolation,

, Ohm

Conductance of isolation,

Capacitive susceptance of isolation, <sup>g</sup> � <sup>10</sup>�<sup>5</sup>

the coal mine Ekibastuz, Angrensor LLP.

, Ohm

, Ohm

<sup>y</sup> � <sup>10</sup>�<sup>5</sup>

<sup>b</sup> � <sup>10</sup>�<sup>5</sup>

Table 1.

67

pho U2 l

#### 4.1 Introduction

The principle of voltage stabilization in the system with the series SC and variable frequency can be explained with a vector diagram of the first harmonics of current and voltages. For such generators that are on the basis of the numerical values of the insulation parameters, it is clear that loss-angle tangent and current in single phase-to-earth fault can evaluate the work of a residual current device on the excavator. Experimental studies regarding the parameters of insulation, loss-angle tangent, and current in single phase-to-earth fault have evaluated the condition of short network under 1000 V in terms of electrical production work in the operation of electrical equipment excavators [1].

The experimental studies were carried out in the coal mine Ekibastuz, Angrensor LLP in the Pavlodar Region of Kazakhstan, to establish the actual values of the basic parameters of the insulation of electrical networks under 1000 V on the excavator EKG-8I.

Compulsory use of the system with insulated neutral networks under 1000 V on the excavators is caused by electricity safety conditions. During the process of solving electrical safety issues in the mining industry, considerable expertise has been built up, especially in the field of research on the condition of electrical insulation with insulated neutral voltage under 1000 V [1]. Neither the methods used to investigate the insulation condition nor the results of these studies can be taken for excavators because the power supply system of the excavator has its own characteristics, namely that there are no long cable lines and the electrical receivers are concentrated in a small area. Put differently, the power of the electrical receiver, such as excavator EKG-8I, is produced by a short network. Electrical receivers operate in different geological, climatic, and meteorological conditions, and this also affects the measurements.

#### 4.2 The study of the condition of insulation

In surveyed excavators, with Ekibastuz coal mine used as the insulation control device, safety rules were prescribed, while automatic insulation monitoring devices were applied, including AIMD, and leakage current LC-2M. Experience in operating electrical equipment positively recommended leakage relay, such as AIMD, which are designed to mine district networks with voltage under 1000 V, that is, for deep mining [14]. Mine networks with voltage under 1000 V contain lengthy branching cable lines, which are powered by the electrical receivers of mining machines and systems. The main reason of ineffective relay is discrepancy between the technical capabilities of RCD and parameters of the insulation network voltage under 1000 V on excavator. However, in most cases, the existing power supply for excavators, which have, as a rule, one main substation, does not make it possible to meet this requirement. This is due to the fact that the relay AIMD, which is a device providing network-wide protection from leakage, switches off all networks when there is any dangerous earth leakage; this in turn can result in a downtime excavator [35].

Consequently, for the safe and efficient operation of the relay leakage, AIMD must review the principles of power supply with users of the excavator and lead parameters of electricity networks in compliance with the technical data relay.

Measurements on the coal mine Ekibastuz were taken by the developed methodic of determining the insulation parameters in networks with isolated Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage… DOI: http://dx.doi.org/10.5772/intechopen.81384

neutral under 1000 V at normal operating conditions of the electrical network of excavators with operating electrical receivers [8].

The developed methodic is based on the method of determining the parameters in the short network with isolated neutral. The method consists of measuring the modulus of linear voltage, phase voltage in respect to earth after the connection between phase and earth the auxiliary conductance. From the measured values of the modulus of linear stress, voltage to earth after the connection between phase and earth the auxiliary conductance, bear the auxiliary conductance in mind, admittance, conductance, and capacitive susceptance of phase-to-ground are determined with satisfactory accuracy [6, 36].

According to the measured values of the modulus of linear voltage, Ul, phase voltage in respect to earth, Uphо, when connecting auxiliary conductance, go, is determined admittance, conductance and capacitive susceptance of isolation by mathematical dependences [37]:

• admittance of isolation

4. Development of method to improve efficiency of residual current device under 1000 V on excavators of mining enterprises

The principle of voltage stabilization in the system with the series SC and variable frequency can be explained with a vector diagram of the first harmonics of current and voltages. For such generators that are on the basis of the numerical values of the insulation parameters, it is clear that loss-angle tangent and current in single phase-to-earth fault can evaluate the work of a residual current device on the excavator. Experimental studies regarding the parameters of insulation, loss-angle tangent, and current in single phase-to-earth fault have evaluated the condition of short network under 1000 V in terms of electrical production work in the operation

The experimental studies were carried out in the coal mine Ekibastuz, Angrensor LLP in the Pavlodar Region of Kazakhstan, to establish the actual values of the basic parameters of the insulation of electrical networks under 1000 V on the excavator

Compulsory use of the system with insulated neutral networks under 1000 V on

In surveyed excavators, with Ekibastuz coal mine used as the insulation control device, safety rules were prescribed, while automatic insulation monitoring devices were applied, including AIMD, and leakage current LC-2M. Experience in operating electrical equipment positively recommended leakage relay, such as AIMD, which are designed to mine district networks with voltage under 1000 V, that is, for deep mining [14]. Mine networks with voltage under 1000 V contain lengthy branching cable lines, which are powered by the electrical receivers of mining machines and systems. The main reason of ineffective relay is discrepancy between the technical capabilities of RCD and parameters of the insulation network voltage under 1000 V on excavator. However, in most cases, the existing power supply for excavators, which have, as a rule, one main substation, does not make it possible to meet this requirement. This is due to the fact that the relay AIMD, which is a device providing network-wide protection from leakage, switches off all networks when there is any dangerous earth leakage; this in turn can result in a downtime excavator [35]. Consequently, for the safe and efficient operation of the relay leakage, AIMD must review the principles of power supply with users of the excavator and lead parameters of electricity networks in compliance with the technical data relay. Measurements on the coal mine Ekibastuz were taken by the developed methodic of determining the insulation parameters in networks with isolated

the excavators is caused by electricity safety conditions. During the process of solving electrical safety issues in the mining industry, considerable expertise has been built up, especially in the field of research on the condition of electrical insulation with insulated neutral voltage under 1000 V [1]. Neither the methods used to investigate the insulation condition nor the results of these studies can be taken for excavators because the power supply system of the excavator has its own characteristics, namely that there are no long cable lines and the electrical receivers are concentrated in a small area. Put differently, the power of the electrical receiver, such as excavator EKG-8I, is produced by a short network. Electrical receivers operate in different geological, climatic, and meteorological conditions, and this

4.1 Introduction

Industrial Engineering

EKG-8I.

66

of electrical equipment excavators [1].

also affects the measurements.

4.2 The study of the condition of insulation

$$\mathcal{Y} = \frac{\mathbf{1}.\mathsf{73}U\_{\text{pho}}}{U\_{\text{l}} - \mathbf{1}.\mathsf{73}U\_{\text{pho}}} \mathbf{g}\_o. \tag{24}$$

• conductance of isolation

$$\mathbf{g} = \left(\frac{\mathbf{3}U\_{\rm pho}^2}{U\_{\rm l}^2} - \frac{\mathbf{3}U\_{\rm pho}^2}{\left(U\_{\rm l} - \mathbf{1}.73U\_{\rm pho}\right)^2} - \mathbf{1}\right) \mathbf{0}.5 \mathbf{g}\_o,\tag{25}$$

• capacitive susceptance of isolation

$$b = \left(\mathbf{y}^2 - \mathbf{g}^2\right)^{0.5}.\tag{26}$$

Based on the results of the determination of admittance, conductance, and capacitive susceptance of isolation in a short line 0.4 kV on the excavator EKG-8I in the coal mine Ekibastuz, Angrensor LLP, the results were processed by using the small sample method. The results from the experimental research regarding the parameters of the insulation as well as an assessment of the results collected using the small sample method are shown in Table 1.

Studying the isolation of electric networks under 1000 V of the excavator showed that the insulation resistance is due to active resistance which characterizes the properties of the dielectric of insulating material used for insulation of live parts


#### Table 1.

The results of determination of the parameters of the insulation in a short line 0.4 kV on excavator EKG-8I in the coal mine Ekibastuz, Angrensor LLP.


the development of technical measures with which to improve the effectiveness of RCD on excavators, taking into account the study of insulation parameters in short

Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage…

There is a drawback when it comes to the existing method of RCD in the network with isolated neutral under 1000 V on excavators. Indeed, this method is based on setting-up a direct current into three-phase mains with a fixed set-point of protection from electric shock. The disadvantage is that the fixed set-point of current of protection does not protect people from electric shocks, as short networks under 1000 V on the excavator have a current of single-phase earth fault, which is less than the set-up value of RCD. In order to overcome this problem, it is necessary to develop a method to improve the efficiency of RCD in a network with

Improving the efficiency of RCDs in a network with isolated neutral under 1000 V is based on switching off the supply due to increase in the phase capacity

A method for improving the effectiveness of RCD in a network with isolated neutral under 1000 V on excavators is explained by the electrical circuit diagram found in Figure 11. The circuit diagram contains: a power transformer T; load interrupt switch QF1, which supplies voltage to the three-phase electric network; three-phase electric network with the phases A, B, and C; electrical receivers; load interrupt switch QF2, which switches capacitors between phases of network and ground; capacitors C1, C2, and C3, being provided by an increase in the current of single-phase ground fault; load interrupt switch QF3, which switches residual current device; residual current device—RCD; total admittance of network isolation

The principle of operation of the scheme of safety shutdown in the short electric network with insulated neutral under 1000 V on excavators is as follows: the power is supplied to three-phase electric network with the phases A, B, and C from power transformer T by load interrupt switch QF1, where electrical receivers are supplied

with voltage under 1000 V of excavator. The capacitors C1, C2, and C3 are connected by load interrupt switch QF2 between the electric network phase and earth to provide increased current of single-phase earth fault. The RCD is connected to a three-phase electric short excavator network by load interrupt switch QF3 [41]. An RCD with a fixed set-point does not allow for the shutting off of the threephase electric network by load switch QF1 when any phase-to-earth insulation of network is damaged. Thus, there is the risk of electric shock. The RCD does not turn off the three-phase electric network when any phase-to-earth insulation is damaged, as the set-up point of current for protection is more than the current of

The scheme of residual current device in electric network with isolated neutral under 1000 V on excavators.

electric networks under 1000 V.

DOI: http://dx.doi.org/10.5772/intechopen.81384

Z1, Z2, and Z3 [40].

Figure 11.

69

isolated neutral under 1000 V on excavators.

with respect to earth when insulation is damaged.

Table 2.

Numeric values of parameters of the insulation and the current of single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I. Z – impedance, R – resistance, X – reactance, tanδ – loss tangent of a dielectric, Io – single-phase earth current.

of the conductors with respect to the ground. Capacitive resistance is higher than active resistance of insulation in networks under 1000 V. As such, the current of single phase-to-earth fault under 1000 V on an excavator is not due to a capacitive component but an active component. Experimental studies showed that the current of a single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I of coal mine Ekibastuz, Angrensor LLP, is about 5 mA. The current of the single phase-to-earth fault in the network under 1000 V on the excavator has a lower value than the set point of RCD. In light of this, it is obvious that the RCD used on excavators by their specification does not provide people with effective protection from electric shocks in networks under 1000 V.

The determined absolute value of the expected capacity of the network is <sup>4</sup>:<sup>30</sup> <sup>10</sup><sup>5</sup> uF, and the range of the network capacity under 1000 V is <sup>4</sup>:<sup>20</sup> <sup>4</sup>:<sup>42</sup> <sup>10</sup><sup>5</sup> uF based on the data in Table 2.

According to the received data, the parameters of the insulation electrical short network are changed insignificantly and are at a high level. This can be explained by the fact that the power supply circuit of the excavator does not contain a network with distributed parameters and the capacity of the network consists of a phase-toearth capacitance only for the electrical receiver. This stipulates for high loss-angle tangent of isolation in the network under 1000 V on the excavator EKG-8I. The current of the single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I has a small value and a small range of variation. There is a range of variation when it comes to the parameters of network isolation, loss-angle tangent of isolation, and current of single phase-to-earth fault in the network under 1000 V due to changes in the supply voltage [38].

Based on the aforementioned evidence, it follows that the workers of mining enterprises receive electric shocks during excavator maintenance work due to the ineffectiveness of RCD. Indeed, as the RCDs used on excavators do not work, this leads to a violation of safety rules regarding the use of electrical equipment of excavators in mining companies. As such, it is necessary to develop RCD for threephase mains under 1000 V on excavators and develop technical measures to increase efficiency of RCD on excavators.

#### 4.3 The method to improve efficiency of residual current device

The development of RCD for a three-phase electric network under 1000 V on excavators is a complex and expensive task, as the principle of operation of RCD for the three-phase electric network with isolated neutral under 1000 V must be changed.

RCDs such as AIMD are used on excavators of mining enterprises. The principle of their operation was based on Scheme 3B developed by Professor. Leybov in the 1950s. This principle is still used today and was thoroughly studied by Shishkin in the 1960s at the Skochinsky Mining Institute. All these studies were conducted to improve the efficiency of RCD in mining electric networks under 1000 V. With this said, however, no detailed investigation into the electric network under 1000 V on excavators has been carried out [39]. In light of this, the most vital area relates to

Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage… DOI: http://dx.doi.org/10.5772/intechopen.81384

the development of technical measures with which to improve the effectiveness of RCD on excavators, taking into account the study of insulation parameters in short electric networks under 1000 V.

There is a drawback when it comes to the existing method of RCD in the network with isolated neutral under 1000 V on excavators. Indeed, this method is based on setting-up a direct current into three-phase mains with a fixed set-point of protection from electric shock. The disadvantage is that the fixed set-point of current of protection does not protect people from electric shocks, as short networks under 1000 V on the excavator have a current of single-phase earth fault, which is less than the set-up value of RCD. In order to overcome this problem, it is necessary to develop a method to improve the efficiency of RCD in a network with isolated neutral under 1000 V on excavators.

Improving the efficiency of RCDs in a network with isolated neutral under 1000 V is based on switching off the supply due to increase in the phase capacity with respect to earth when insulation is damaged.

A method for improving the effectiveness of RCD in a network with isolated neutral under 1000 V on excavators is explained by the electrical circuit diagram found in Figure 11. The circuit diagram contains: a power transformer T; load interrupt switch QF1, which supplies voltage to the three-phase electric network; three-phase electric network with the phases A, B, and C; electrical receivers; load interrupt switch QF2, which switches capacitors between phases of network and ground; capacitors C1, C2, and C3, being provided by an increase in the current of single-phase ground fault; load interrupt switch QF3, which switches residual current device; residual current device—RCD; total admittance of network isolation Z1, Z2, and Z3 [40].

The principle of operation of the scheme of safety shutdown in the short electric network with insulated neutral under 1000 V on excavators is as follows: the power is supplied to three-phase electric network with the phases A, B, and C from power transformer T by load interrupt switch QF1, where electrical receivers are supplied with voltage under 1000 V of excavator. The capacitors C1, C2, and C3 are connected by load interrupt switch QF2 between the electric network phase and earth to provide increased current of single-phase earth fault. The RCD is connected to a three-phase electric short excavator network by load interrupt switch QF3 [41].

An RCD with a fixed set-point does not allow for the shutting off of the threephase electric network by load switch QF1 when any phase-to-earth insulation of network is damaged. Thus, there is the risk of electric shock. The RCD does not turn off the three-phase electric network when any phase-to-earth insulation is damaged, as the set-up point of current for protection is more than the current of

of the conductors with respect to the ground. Capacitive resistance is higher than active resistance of insulation in networks under 1000 V. As such, the current of single phase-to-earth fault under 1000 V on an excavator is not due to a capacitive component but an active component. Experimental studies showed that the current of a single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I of coal mine Ekibastuz, Angrensor LLP, is about 5 mA. The current of the single phase-to-earth fault in the network under 1000 V on the excavator has a lower value than the set point of RCD. In light of this, it is obvious that the RCD used on excavators by their specification does not provide people with effective protection

Numeric values of parameters of the insulation and the current of single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I. Z – impedance, R – resistance, X – reactance, tanδ – loss tangent of a

Z, Ohm R, Ohm X, Ohm tan δ, Io, mA

72993 70922–74627

0:80 0:80–0:81

4:93 4:84–5:04

The determined absolute value of the expected capacity of the network is

According to the received data, the parameters of the insulation electrical short network are changed insignificantly and are at a high level. This can be explained by the fact that the power supply circuit of the excavator does not contain a network with distributed parameters and the capacity of the network consists of a phase-toearth capacitance only for the electrical receiver. This stipulates for high loss-angle tangent of isolation in the network under 1000 V on the excavator EKG-8I. The current of the single phase-to-earth fault in the network under 1000 V on the excavator EKG-8I has a small value and a small range of variation. There is a range of variation when it comes to the parameters of network isolation, loss-angle tangent of isolation, and current of single phase-to-earth fault in the network under

Based on the aforementioned evidence, it follows that the workers of mining enterprises receive electric shocks during excavator maintenance work due to the ineffectiveness of RCD. Indeed, as the RCDs used on excavators do not work, this leads to a violation of safety rules regarding the use of electrical equipment of excavators in mining companies. As such, it is necessary to develop RCD for threephase mains under 1000 V on excavators and develop technical measures to

The development of RCD for a three-phase electric network under 1000 V on excavators is a complex and expensive task, as the principle of operation of RCD for the three-phase electric network with isolated neutral under 1000 V must be

RCDs such as AIMD are used on excavators of mining enterprises. The principle of their operation was based on Scheme 3B developed by Professor. Leybov in the 1950s. This principle is still used today and was thoroughly studied by Shishkin in the 1960s at the Skochinsky Mining Institute. All these studies were conducted to improve the efficiency of RCD in mining electric networks under 1000 V. With this said, however, no detailed investigation into the electric network under 1000 V on excavators has been carried out [39]. In light of this, the most vital area relates to

4.3 The method to improve efficiency of residual current device

<sup>4</sup>:<sup>30</sup> <sup>10</sup><sup>5</sup> uF, and the range of the network capacity under 1000 V is

from electric shocks in networks under 1000 V.

58480 57143–59880

dielectric, Io – single-phase earth current.

45662 44643–46512

Industrial Engineering

Table 2.

<sup>4</sup>:<sup>20</sup> <sup>4</sup>:<sup>42</sup> <sup>10</sup><sup>5</sup> uF based on the data in Table 2.

1000 V due to changes in the supply voltage [38].

increase efficiency of RCD on excavators.

changed.

68

single-phase earth faults in the three-phase network of the excavator. In order to disable the three-phase network when insulation is damaged, the current of singlephase fault in the network is increased by means of connecting capacitors C1, C2, and C3 between the phases of the electric supply and the ground by load switch QF2. In this case, the current of single-phase circuits in the excavator's three-phase network will be more than the current of the set-up point of RCD, which will activate the RCD. Thus, the switching off is made possible thanks to the load interrupter switch QF1 supplying voltage from the power transformer [40].

voltage up to 1000 V in mining enterprises through the development of

Special Issues of Ensuring Electrical Safety in Networks with Isolated Neutral Voltage…

phase-sequence voltage and phase voltage to earth, with an additional

A method of measuring the admittance of network with an isolated neutral voltage up to 1000 V is based on the measurement of the modulus of the zero

conductance where the value of the regulation is made additional conductance in conduction to ensure the equality of the modulus of phase voltage to earth and zero phase-sequence voltage. In ensuring the equality of zero phasesequence voltage and phase voltage to earth connection of additional conductance, it corresponds to the admittance network isolation.

The simulation model of method of measuring the admittance of insulation in the Matlab/Simulink environment was modulated. The developed model allows for the regulation variable resistor to be used to simplify the calculations

Developing a method of measuring the admittance of insulation networks with an isolated neutral voltage up to 1000 V will provide improved accuracy and speed measurement admittance network isolation. The proposed method is simple, as the instrumentation, single-phase voltage transformers, required for measuring the admittance network isolation is in the service manual enterprise

of the parameters of network isolation. Due to the data received in the regulation of the variable resistor to 2068 Ohms, the true value zero phasesequence voltage and phase A voltage to earth are equal to 140.8 V. Thus, the variable of the admittance y corresponds to 2068 Ohms, which comprises

5. The experimental data obtained are composed of numerical values of the parameters of the insulation on the excavator EKG-8I of coal mine Ekibastuz, Angrensor LLP. It was established that the insulation resistance is due to active resistance, which characterizes the properties of the dielectric of insulating material used for insulation of live parts of the conductors with respect to ground. Capacitive resistance is higher than active resistance of insulation in

It is found that the RCDs used on excavators by their specifications do not

Organizational and technical measures aimed at improving the reliability

protect people from electric shocks while also reducing the number of accidents at

The work was carried out in accordance with the contract no. 242 of March 17, 2018, at the S. Seifullin Kazakh Agro-Technical University with the Ministry of Education and Science of the Republic of Kazakhstan under the project no.

and level of electrical safety in electrical mining enterprises will help to

A new method aimed at improving the effectiveness of RCDs in electric network under 1000 V has been developed and is based on setting up the DC into a threephase network with a fixed set-point of protection from any phase-to-earth insulation damage, where the equipment is switched off by residual current device when live-line bare-hand touching of electric equipment occurs. This is due to increases in

provide effective protection from electric shocks in a short network with voltages under 1000 V as the current of single-phase earth faults in the network under 1000 V on the excavator has less value than the current of the RCD set-up

methods to control the condition of insulation.

DOI: http://dx.doi.org/10.5772/intechopen.81384

0.48 mS.

energy management.

networks under 1000 V.

the phase capacity with respect to earth.

point.

work.

71

Implementation of the developed method to improve the effectiveness of RCDs in electric networks under 1000 V will ensure the growth of level of electrical safety when using electrical installations and reduce the number of accidents on excavators.
