TILI Automation

 In this post, we will see the concept of a line choke or reactor. Line choke is an inductance connected to the VFD input or output circuit. It is a component that forms a magnetic field as current flows through it and when the current increases, it limits the increment in current by producing a voltage or emf across it that opposes it. This protects the VFD from unwanted spikes, transients, and harmonics. The reactor is used on either the input side or output side of the VFD. Refer to the above image. The inductance is shown on the input side and the output side is nothing but the line choke. It is normally used for VFD’s which have a rating of more than 1 KVA. Let us understand its basic working. It is not always necessary that a current wave be sinusoidal. When it is not sinusoidal, it contains harmonics. Harmonics are a large current distortion. If you see the basic equation of an inductor, it is – V = L (di/dt) Here, V is the voltage, L is the inductance of the choke or reacto...

 A simple diagram is shown here, where a single loop controller controls the speed of a DC electric motor using the concept of feedback control. Single Loop Controller The motor receives its power from the Variable-Speed Drive (VSD), and reports shaft speed to the controller by means of a tachogenerator (“tach”) which generates a DC voltage proportional to shaft speed. The VSD (or VFD) receives the command signal from the loop controller and tries to maintain the motor speed accordingly. Also, the VSD sends the actual motor speed signal back to the loop controller. Note: For study purpose, we consider the 12V small motor. We can replace the single-loop controller with a PID controller in PLC or DCS systems also. Lets study in the following ways: Question 1: If we Place the controller into manual mode and adjust the controller’s output to see how the motor spins (and how its speed is registered on the controller’s process variable display). Question 2: If we Place the controller int...

 Getting started with Allen Bradley Powerflex VFD  To get started with Variable Frequency Drives, we have to know why industries are using VFD?. As the name explains, the VFDs are used to vary the frequency of the AC wave they are receiving and send it to the output where an AC motor is wired. So ultimately we are using VFD to control the speed of the AC motor. We all have heard of Motor Control Center (MCC), they’re used to supply the power to motors and also used to start the motor in an efficient way with protection. Now we might have a question whether I should have a separate control to start the motor when we use a VFD? The answer is we don’t need a separate control when we use a VFD. VFD provides the following advantages, smooth starting smooth acceleration & deceleration time stopping methods reversal of motor reduce harmonics increase power factor Allen Bradley Powerflex VFD Now that we understand why we prefer VFD. we are gonna jump on to how it is being used and...