Abstract

Develop a methodology and algorithms for operational monitoring and diagnostics of electric motors in a distributed control system

Contents

Relevance of the topic

At present, production of complex power equipment is widely used that requires constant monitoring in the event of an emergency. The cost of its repair and downtime is much higher than the cost of systems that can prevent an accident or substantially reduce the damage. Application of modern computational systems let us to solve a problem of different nature related to the monitoring of parameters of controlled objects, to optimize working conditions, determine the optimal operating conditions to predict the development of the condition of equipment.

The most common of power mechanisms are electric motors. In real conditions of production, they are highly susceptible to deterioration due to severe operating conditions. To control the parameters of the electric motor used stand-alone unit control and protection of APM, AMP-M, COWM.U developed by AMI [1].

Protection of electric motor apparatus AMP provides engine protection under the following emergencies:

• unfinished start;
• technological overload;
• pinching (rollover);
• loss of power phases.

Apparatus of control working and protection of electric motors COWM.U depending on their realizing functions has several variants of execution:

• COWM.U1 - to protect the motor during a rollover and the start-up is incomplete;
• COWM.U2 - to protect the motor with technological overload;
• COWM.U3 - combines the functions of COWM.U1 and COWM.U2;
• COWM.U4 - serves COWM.U3 and additionally the maximum-current protection.

The device protection of electric motors based on a microcontroller AMP-M implements advanced features in comparison with AMP. Through the use of the microcontroller an opportunity to implement new posibility and more flexible control algorithms and motor protection. Below are the security features of the electric motor, running the device, when a variety of situations:

• unfinished start;
• technological overload;
• pinching (rollover);
• mode of operation (AMP-M2);
• loss of power phases (AMP-M2) (operation of the apparatus with the loss of current in one or two phases);
• loss of productivity ("dry run" pump);
• overheat;
• reduction of insulation resistance on the ground (when working with the sensor ground leakage type ELS).
The device by connecting an external display unit that allows you to visualize some of the parameters of the motor.

However, such devices do not allow for automated and operational control of condition of the electric motor from the working place of operator. Besides, does not provide the possibility of receiving and storing information on operating conditions and motor status for a long period, which does not allow to determine the trend of wear and to predict the residual resource. With an increase in the number of motors increases considerably the complexity of control.

Object and problem

The aim of this paper is to solve the problem of determining trends of wear and residual prediction resource of motor, the realization of constant control, storage conditions and operating conditions for a long time. Decision the problem of rising efficiency of exploitation the electric motors is possible using the proposed automated control system (ACS), the structure is shown in Figure 1.

Problems master's works:

• The method and diagnostic algorithms motor;
• Methods and algorithms for power control motor;
• Control the motor winding resistance and diagnosis of changes in resistance on the basis of statistical data;
• Monitoring and diagnostics of the condition of electric motor in real time;
• Methods and algorithms Spectral analysis of the current [6, 7];
• Practical implementation of the security appliance motor;
• Creating a practical implementation of the computer network [2, 3];

Alleged scientific novelty and practical value of the planned

Scientific novelty:

• A general approach to implement a typical system proposed;
• The technique and algorithms for spectral analysis of currents;
• The technique and algorithms for power control engine;
• Translate comparative evaluation of existing algorithms for motor protection;

The practical value:

Based on these studies and the results will be developed device protection of motor, electrical network RS-485 using ModBus protocol and automatic control system of electric motors in order to implement the production of working product.

Conclusion

As a result of the work at the moment, created a theoretical model of information collection system and electric motor control in industrial conditions. Further redesign and deepening of subject matter transport layer protocol data to a projected version of the network. At the moment, is close to completing a theoretical model of intellectual protection system of three-phase motor. Most of the set to achieve objectives theoretically permitted, but require laboratory and experimental verification.

Note

When writing this abstract the master’s qualification work is not completed. Date of final completion of work: December, 1, 2011. Full text of the work and materials on a work theme can be received from the author or his scientific supervisor after that date.