Power in Motors

Power in Motors

AC motors are either single-phase or three-phase. For a single-phase motor, the electrical input power is given by Equation (A).

 (A) Pin = VIcosθ  V is the rms line voltage, I is the rms line current, and cosθ is the power factor.
 As we learned in the lesson on three-phase,

 (B) Pin = √3 VIcosθ  The output mechanical power is:

 (C) Pout = Toutωm  Pout is the output mechanical power, Tout is the output torque, and ωm is the angular frequency of the shaft.

 (D) Pin = Pout + Ploss 
Ploss refers to the copper, eddy current, hysteresis, friction, and windage losses.
Pout is usually given in horsepower (746 W/HP). The efficiency of a motor (η) is the ratio of the powers:

 (F) η = Pout/Pin
Typical values for industrial motors are between 85% and 95%. It should be understood that these efficiency are for full load. Efficiency decreases significantly for light loads.

 Since motor speeds are usually given in rpm rather than shaft angular frequency, conversion is frequently necessary:

 (G) ωm = nm(2π)/60  nm is the motor shaft rotation in rpm.

What is a VFD ?

What is a VFD ?

Variable Frequency Drive (VFD) is a type of motor controller that drives an electric motor by varying the frequency and voltage supplied to the electric motor. Other names for a VFD are variable speed drive, adjustable speed drive, adjustable frequency drive, AC drive, microdrive, and inverter. Frequency (or hertz) is directly related to the motor’s speed (RPMs). In other words, the faster the frequency, the faster the RPMs go. If an application does not require an electric motor to run at full speed, the VFD can be used to ramp down the frequency and voltage to meet the requirements of the electric motor’s load. As the application’s motor speed requirements change, the VFD can simply turn up or down the motor speed to meet the speed requirement.

SIMATIC Step 7 Addressing

SIMATIC Step 7 Addressing

Addressing the PLC Signal Modules is paramount to effective service and maintenance. In this lesson the viewer will understand the concept of Bit, Bytes and Words and in doing so will learn how the Signal Modules are addressed.

Once the address system has been set up the viewer will also be shown how to Monitor and Modify addresses during a commissioning phase.

+ What is Bits / Bytes/Words
+ How to dddressing the I/O Modules
+ How  to setting up PLCSIM
+ How to Monitor / Modify Variables


Digital I/O

Analog  I/O

setting up PLCSIM
Cr: https://www.automationtubecentral.com

What is an Inverter?

What is an Inverter? – Inverters offer speed or torque control of electric motors.

Cr: Gloogle.com

Maybe you have walked past without noticing them or maybe you know exactly how many you have, either way electric motors play an important role in our everyday lives which most of us are unaware of but, they move and run most things we need for business and pleasure.

All these motors consume electricity so need a corresponding amount of energy to provide the torque or speed needed. If the torque or speed is too high or low, mechanical controls are used to control output. A motor’s speed should match exactly what is required by the process, otherwise the result is inefficiency with a lot of wasted materials and energy.

Not knowing how to control motors can mean a lot of energy gets wasted which isn’t good for any business. A way to control these motors, which not only saves energy, but improves productivity and reduces maintenance costs, is to use an inverter.

What is an Inverter?

So what is an inverter? Ours are sometimes called AC drives, Variable Speed Drive (VSD) or Variable Frequency Drives (VFD).  The correct term is frequency converter. They sit between the electrical supply and the motor. Power from the electrical supply goes into the drive. The drive then regulates the power which is then fed to the motor. Inside the drive, the input power is run through a rectifier that converts the incoming AC power to DC power.

DC power is then fed into capacitors inside the drive to smooth out the electrical wave form which provides a clean power supply for the next step. Power then flows from a capacitor to an inverter which changes the DC power to the output AC power that goes to the motor. This step allows the drive to adjust the frequency and voltage that is supplied to the motor based on your current process demands. This means the AC power is run to the speed or the torque of the demands needed. This is why you can save large amounts of money using our AC drives.

What exactly is Profibus-DP

What exactly is Profibus-DP ?

 It's very simply explained  , very helpful and made thing more clear about the Profibus-DP.

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