MOTOR CONTROL & CONTROL CIRCUITS

INTRODUCTION

Motors are the most commonly and widely using electrical equipment in industry. They are the most common prim mover for many mechanical devices. Motors can be classified as AC or DC motors which are driven using AC or DC current. Father classification can be given as bellows. In this Industry, there are five DC motors using for drive weigh feeders because speed controlling is very easily done. But with the introduction of VSD’s all DC drivers are replacing with wound rotor induction motors and still squirrel cage induction motors are using for when needed high starting torque and high power.
Control circuits use to operate machines automatically by using limits and sencers. The circuit can design according to operation of the machine. High power motors are also started using Control circuits.so; function of the control circuits can describe using starting method of the motors

SLIP RING MOTORS

The slip ring or wound rotor motor is an induction machine where the rotor comprises a set of coils that are terminated in slip rings to which external impedances can be connected. The stator is the same as is used with a standard squirrel cage motor. By changing the impedance connected to the rotor circuit, the speed/current and speed/torque curves can be altered. The slip ring motor is used primarily to start a high inertia load or a load that requires a very high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low current from zero speed to full speed.

WOUND ROTOR INDUCTION MOTORS

These are the most widely used motor type in industry. Low cost, less maintenances requirements, Reliable operation, wider availability, Easy to rewind. The terminal box of this motors have six terminals, actually they are the both ends of thee windings. By these terminals we can connect the winding as a delta connection or a star connection

COMPUTER NUMERICAL CONTROL MACHINES

INTRODUCTION

Today, computer numerical control (CNC) machines are found almost everywhere, from small job shops in rural communities to many companies in large urban areas. Truly, there is hardly a facet of manufacturing that is not in some way touched by what these innovative machine tools can do. Everyone involved in the manufacturing environment should be well aware of what is possible with these sophisticated machine tools. The design engineer, for example, must possess enough knowledge of CNC to perfect dimensioning and tolerance techniques for work pieces to be machined on CNC machines. The tool engineer must understand CNC in order to design fixtures and cutting tools for use with CNC machines. Quality control people should understand the CNC machine tools used within their company in order to plan quality control and statistical process control correctly. Production control personnel should be abreast of their company's CNC technology in order to make realistic production schedules. Managers, foremen, and team leaders should understand CNC well enough to communicate intelligently with fellow workers. And, it goes without saying that CNC programmers, setup people, operators, and others working directly with the CNC equipment must have an extremely good understanding of CNC machines. In this chapter, I will explore the basics of CNC machine that I gain in the training.

Basic Hardware Components

• Panel Control Unit (PCU)

• Keyboard (KB)

• Machine Control Panel (MCP)

• Profibus cable 72/48 (PP 72/48; 72 digital inputs,48 digital outputs)

• Drive Module

Basic Software Components

• System software on the permanent flash memory on the PCU

a) Boot software

b) HMI (Human Machine Interface) software

c) NCK (Numerical Control Kernel) software

d) PLC (Programmable Logic Control) software

• Toolbox software