Dec 4, 2018

How To Find PPR and Maximum Frequency of Encoder

Encoder comes with a specified PPR i.e pulse per Revolution and Maximum Frequency output of the pulses given by encoder. Generally, encoders are mounted on the shaft of the conveyor, so according to the resulting RPM we should select the encoder with a proper PPR and output frequency.

How To Find PPR and Maximum Frequency of Encoder

How to Find PPR and Maximum Frequency of Encoder

The encoder is interfaced with the PLC for counting the pulses given by encoder and taking the feedback. PLC inputs also have a frequency range for the pulses which it can accept. So calculating the frequency of pulses by the encoder is important in an application. Below is the formula to find the Max. The frequency of encoder in from the PPR and RPM.

Max. Frequency of encoder in Hz = (RPM / 60) * PPR

So if the encoder is mounted where the RPM = 2000 and PPR of the encoder is 360 the frequency of encoder will be 12KhZ. So we could find out that our PLC will be able to count pulses with this frequency or not.

Recommended Article: Using High Speed Counter in Omron PLC

Let us also see the difference between Single turn and Multi-Turn encoders.

In single turn Encoder, the output code is repeated after every single revolution of the encoder shaft i.e we can not actually determine how many turns have encoder made 1 or 1000.

In Multi-turn Absolute encoders, the output is unique for each revolution or for every shaft positions up to 4096 revolutions and we can get to know that the numbers of rotation of Encoder.

For more updates on Encoders you can subscribe to get all information in yours Inbox. Subscribe to Automation-Talk by Email.

Aug 30, 2018

How to Save Energy using VFD/Inverter/AC Drive

Variable Frequency Drive or VFD is a power electronics device which has revolutionized the Electrical Industry. VFD have made possible the speed and frequency control of the AC Motor. VFD gives a load of other advantages other than speed control. VFD is the best starting method for AC Motor. Also, the energy saving feature in drive makes an added advantage for saving the electricity and thus reducing the cost.

How to Save Energy

Save Energy by Using Baldor VFD

Baldor VS1MD series VFD have a special feature through which we can save energy and thus reduce the cost of electricity bills. In almost all the industries where there are many motors, most of the electricity bill is raised from current consumption by these motors. But by installing Baldor VFD we can get up to 30% energy savings and thus the cost of the drive can be recovered in just 1 Year.

All the drives have PWM output, so it means that even if we don’t set the parameter we will get the energy savings and that is for sure. If we compare two motors of same ratings, for example, there are two motors of 10 HP Motor A and Motor B. Motor A is run through Star Delta Starter and Motor B is through VFD.

Both the Motors A and B are used in the same application with the same load condition and the same environment. If we install an Electric Meter and monitor the Units consumption then we will find that there will be around 20 to 30% lesser electric units consumed by Motor B which is run through VFD.

Parameter Setting in Baldor VFD for Energy Savings

To boost the energy savings in Baldor VFD, there is one Parameter. Parameter Number F40, in this put the value in between 0 to 30. It adjusts the output voltage according to the load status. It is set as a percent of a maximum output voltage.

When there is any pump or fan application, setting this parameter can dramatically reduce energy consumption by decreasing the output voltage with light loads or load behavior.

We will be discussing more about VFD Application and its advantages, so till then subscribe to Automation-Talk by Email, so that you can get all the latest updates.

Aug 7, 2018

Understanding Torque and Its Simplest Explanation

In the past few topics of AC Motor basics we have seen about general motor terms, different types of motor load and the Calculation of Synchronous speed from Poles. We all frequently use term called Torque in our day to day work life. But, do we really know the actual meaning of "Torque". We got many request from our readers to explain the term torque in simple words. So get a cup of coffee and sit back. Subscribe to Automation-Talk by Email.

Understanding Torque and Its Simplest Explanation

What does Torque Signify?

In our industrial applications when we have to select the driving motor for any load we are always concerned about the horsepower, but believe me the real driving force is TORQUE and not horsepower. In the simplest word torque is the twisting/rotational force exerted by the drive on the load. Now let us take a simple example.

Do you remember that sometimes you try to open the lid or open a bottle but after so many tries it does not open? Do you know the reason why it doesn't open? Because we are unable to supply or apply the adequate torque to open the lid. The solution for this can be a) grit our teeth and try harder, b) use a rubber pad, or cloth, to increase the ability to transmit torque without slippage, or c) use a mechanical device to help multiply our torque producing capability. If still, it doesn't open then give it to some stronger person!!

Well, the main motive behind the above example was just to make u feel something about torque. We are always confused among HP and Torque. Now let us suppose that after so much try also the lid did not open and now we will wrap a cord around the lid and supply a force to the end of the cord through a scale. See the below diagram.

Example for Torque Calculation

Can we tell the torque required in this case? Yes, we can, the torque requirement will be the force as depicted on scale multiplied by the radius of the lid. For example, if the reading of force on the scale is 17 lbs( at the time of breakaway of lid) and the radius is 3 inches then the torque requirement would be:-

T = F * R = 17 * 3 = 51 lb.inches

Simplest Explanation of Torque

However, the above example gives a clear illustration of the torque but lets us discuss one more thing which is observed in industrial applications. If we recall the above example then we can derive one more term called "Stiction". Stiction can be defined as the amount of torque required to make a load lose and start the first revolution. Stiction is nothing but only the second name of the breakaway torque and frankly speaking for every industrial application the breakaway torque requirement of any load is greater than the continuous torque requirement for running the machine.

The amount of "stiction" present in a machine will be dependent on the characteristics of the machine as well as the type of bearings that are used on the moving parts. Below you can see a picture in which the breakaway torque requirement of different machines is shown.

So, we have got now a clear view of the torque and its characteristics, in the next few days we will try to see more different types of torques and detailed explanation of torque in a simple way. Till then you can subscribe to get all latest updates via Email.

Jul 23, 2018

Advantages/Benefits of Servo Motor Over Induction Motor

We have discussed about the servo basics and servo control terminology in the previous article. We have studied about the different components of a servo control. Today in this post we will see that what are the advantages that we get by using the servo motor over the AC Induction motor. This article is in continuation to the previous one and here we will learn more about servo control.

Advantages and Benefits of Servo Motor Over Induction Motor

Servo Motor V/S AC Induction Motor

Let us, first of all, see that what are the advantages of using the servo motor. Why it is that Servo Motor gives better efficiency for many applications. Suppose that an Induction motor is connected to run a grinder at full speed, we can expect to get some level of performance in this case. But is same grinder is run through Servo Motor we will get the next level of performance. So how it is achieved? Let us discuss in detail.

As we have discussed in the previous post that a servo motor is always used with a control and feedback device. The servo control issues the command for the position and the feedback device monitors the load and inform the servo control so that the control can correct the position if there is any error.

Advantages of Servo Motor Over Induction Motor

1. Increased Performance:- A servo motor has got more acceleration rate and higher speed capabilities compared to the induction motor and thus allowing the enhancing the production rate of the machine.

2. Smaller Size:- Servo motor has the higher output torque rating for the same size of the rotor. Thus Servo motor can be installed in a place where space is of prime concern.

3. Less Weight:- Weight of the Induction Motor is more than the servo motor for the same rating.

4. Highly Efficient:- A servo motor is designed in such a way to have peak efficiency and thus a better power conversion factor and thus saving the power.

5. Quick Positioning:- Servo motor can be issued a command to move accurately to the desired position in very less time, this is not possible with Induction motor.

6. High Degree of Accuracy:- In critical applications where we need the accuracy in microns or mm, the servo motor can provide it as it is designed for highly precise positioning.

7. Control-ability:- Last but not the least, as the servo control is used along with the servo motor thus a full control is achieved over the servo motor.

Also, one major point to be noted here is that the power of servo motor is utilized only when a position move command is issued to servo motor and rest of the times servo motor is normally turned off, thus a large amount of power is saved.

We hope that after reading this article about the advantages of servo motors over induction motor, we have come one step ahead. In the next article, we will discuss about the Permanent magnet DC Motor and AC Brushless Motor, till then you can subscribe to Automation-Talk by Email to get all latest updates.

Jul 4, 2018

Test Procedure of AC Induction Motor

AC Induction Motors are the heart in any type of Industries, for any work you require Motor to do the work. Hence there must not be any issue in calling "AC Motors" as the heart for Industrial applications. Specification of AC Motor includes its Capacity i.e Rating of the Motor, its Frame Size, Rated Voltage and Current, Frequency and its scale of Insulation. But, how many of us knows the testing of AC Motor? Don't worry we will see here the detailed procedure to test the AC Induction Motor

Test Procedure of AC Induction Motor

How to Test the AC Induction Motor

As we buy the AC Induction Motor from the market, it has been tested previously at the manufacturing time for all the defects, But still, we should also know and understand the testing procedure of AC Induction Motor. We will see step by step testing procedure here for AC Motor.

Magering:- Mager is used to test the Insulation of the Motor. But what is Mager??

Mager is actually a small DC Generator rotated by hand, it generates High Voltage and less Current. For the testing purpose,
upto 2000V it is hand operated and above 2000V it is mechanically operated.

The resulting outcome equation is as:- 1mohm / KV and 0.44mohm / 440V.

Drop Test:- Drop test is used to check the resistance of individual winding, and they should be equal for a more efficient AC Motor.

<> Absorption Coefficient Test:- It is same as Magering procedure. In this test procedure of AC Induction Motor, Insulation value is measured for two different time duration one for t=15 sec and other for t=60sec.

If Insulation Value for t=15 sec is less than 1 then AC Motor OK.
If Insulation Value for t=15 sec is greater than 1 then AC Motor NOT OK.

Recommended Article: How to Change Servo Drive Parameter using Omron CX Drive

So It may be possible that moisture is present in the Windings of AC Induction Motor, To remove the Moisture from the Motor Windings, Raise the temperature of motor windings gradually so that all the moisture evaporates out. But one point to keep in Mind is that the rate of change of temperature of Motor Windings should not be greater 1 deg. celcius per 30 minutes.

After removing the moisture from the motor windings again perform the Absorption Coefficient Test and if this time Insulation Value for t=60sec is less than 1 then AC Motor OK. If you like this article, please Subscribe to Automation-Talk by Email and share this article with your friends.

You can also contribute to our blog, just let us know through Facebook or commenting below.

Jun 18, 2018

PLC Programming for Tank Level Measurement using Ultrasonic Sensor

In our earlier post we saw the PLC Logic for Auto filling of Tank using digital inputs for LOW and HIGH Level signals. Today in this post, we will see how we can measure the level of a tank using the Ultrasonic/Capacitive level sensor and accordingly ON/OFF the PUMP at low and high levels.

PLC Programming for Tank Level Measurement using Ultrasonic Sensor

PLC Programming for Tank Level Measurement using Ultrasonic Sensor

First of all, we need to choose the Ultrasonic/Capacitive level sensor according to our tank level height. The sensor will give a 4-20mA signal to PLC and accordingly we will calculate the level in the tank.

PLC Logic Development:-

Now, we need to connect the analog input from the ultrasonic sensor to PLC, we have already told that in our earlier post. You can see here.

After that, we have to write SCL (scaling instruction) in the PLC to covert the value received by PLC to the scale we want. For example, if the height of our tank is 5000cm, PLC will receive the 4-20ma signal and internally will convert it into a range of o to 0FA0 (hexa) and with the help of SCL instruction we will scale this value between 0 to 5000.

So that when the Ultrasonic sensor will give 4mA signal then level in the tank will be zero and when a signal of 20mA will be received then level in the tank will be 5000cm.

In SCL instruction, we have to define the scaling parameters in some D:-

D200 - 0
D201 - 0
D202 -5000 (hexa)
D203- 0FA0 (hexa)

Here the value 0 to 0FA0 received by PLC will be scaled to 0 to 5000 (our tank height).

Now in this PLC Program we have kept the low level at 2500cm and high level at 4600cm. You can download the PLC program from below, we have built the PLC Program using the Omron CX-supervisor software. Both the .cxp and .pdf file are included in.

Download PLC program for Tank Level Measurement.

Hope you like this PLC program on controlling your Tank according to the measurement using an Ultrasonic sensor. If you face any problem with this PLC Program or want any modification then write us in the comment section. Also you can subscribe to receive latest updates about PLC Programming, SCADA tutorials, HMI programming, MODBUS programming, VFD Installation. Subscribe to Automation-Talk by Email.

May 1, 2018

How to Choose your PLC or PLC Choosing Criteria

Choosing a PLC or Controller for your Process is very important as it helps in cost optimization. If you choose a wrong PLC it may happen that you are out of I/O's while programming or maybe you have the excess of I/O's left which are of no use. So it becomes very important that you choose a right PLC for your Automation Process.There are several criteria that help in choosing a PLC. Before knowing the Criteria of choosing a PLC you should know basics of PLC. Subscribe to Automation-Talk by Email.

Below are some points which will help in choosing a PLC but keep in mind that you should know exactly the need of the Customers and should know how many Input and output he wants for present and for future.

PLC are chosen generally on the basis of some requirement of the company or individual person. We should keep in mind the following below point while choosing a PLC.

How to Choose your PLC or PLC Choosing Criteria

Some of the PLC choosing criteria are

1. Number of I/O's:

It is very important that you know the exact number of input and output that are going to be used in the process for best and economical use.

2. Type of I/O's:

The Automation Engineer should also know the type of I/O's whether he needs a digital input like Sensor, Push Buttons etc. or an analog input like RTD, thermocouple etc. The requirement for Output should be also known as what type of Output is required whether you required a digital Output like Relay, Contactor, Lamp etc. or you need an Analog output like Drive and Control Valves.

3. Memory size of PLC:

Choosing PLC memory size is also important as you may be out of space in PLC while writing a PLC program if you choose less memory size PLC.

4. Compact or Modular PLC:

Compact Type PLC are those which has Power supply and controller in the same housing while Modular type PLC has power supply and controller in a different housing. So it is good to choose compact or Modular type PLC according to your requirement.

5. AC or DC PLC:

AC PLC's are those which are operated on 220 V i.e. they require 220 V for running. Whereas DC PLC requires only 24V for Running. So you should know which type of PLC will be good for you according to the Power Supply available in your Control Panel.

6. Sinking and Sourcing PLC:

Making a PLC source at Input or making a PLC sink at input depends upon the requirement of the user so PLC should be chosen in that way. Some PLC may support both Sink and Source at Input and Output Both.

Recommended Article: Understanding Difference Between Source & Sink in PLC's

7. PLC Scan Time:

PLC scan time is a time needed for PLC to completely Scan one cycle of PLC. It may consist of reading PLC input status, clearing PLC memory, Executing the PLC program and updating the Output. The PLC with less Scan time are found to be more Costly.

8. Number and type of Communication ports in PLC:

The number of communication Port or type of communication port is also very important in choosing a PLC. Suppose you want to communicate your PLC in MODBUS but you don't have a MODBUS port so your PLC is of no use. Also, take an example where you want to communicate an HMI with RS232 port but you don't have one. So communication Port should also be in mind while choosing a PLC.

So these were some of the Criteria for Choosing a PLC which should be kept in mind while you buy a PLC. PLC choosing criteria of Allen Bradley, ABB, Siemens, Omron, Mitsubishi, GE Fanuc, Delta, Fuji, GE or any other PLC are same in all cases. Subscribe to Automation-Talk by Email for more Tips and Tutorials.

Apr 3, 2018

Difference Between Absolute and Incremental Encoder

Many new Automation Engineers are in confusion that what is the difference between Absolute and Incremental Encoder while they work on Encoder. And every Automation Engineer has its own View in defining absolute encoder and incremental encoder. First of all, we should know what is an Encoder, What are types of Encoder, what does Encoder do, How to program an absolute encoder or incremental rncoder in a PLC. Now lets, start with knowing what is an Encoder. Subscribe to Automation-Talk by Email.

Omron Encoder

In simple form, Encoder is a device which converts motion into a sequence of digital pulses. The encoder has mainly two configurations i.e. Linear and Rotary. Now Rotary encoder can also be divided into Absolute and Incremental (relative) Encoders.

Absolute Encoder are encoder where a digital word resembles to each rotational position of Shaft.

Incremental Encoder are encoder which produces digital pulses as the shaft rotates, and allow the measurement of relative position of the shaft.

Recommended Article: PLC Programming For Counting Encoder Pulses

What is the Difference Between Absolute and Incremental Encoder

Every people has its own view on Encoders. So here are some differences between Absolute Encoder and Incremental Encoder from the different view of people. Some Engineers simply distinguish Absolute encoder as Parallel and Incremental Encoder as a series Encoder.

Absolute Encoder is a holding encoder i.e. it knows its position even after power failure whereas Incremental encoder cannot retain its position after the power failure and we always need a home position for Incremental Encoder.

Incremental Encoder gives a pulse train indicating units of movement and direction whereas An absolute gives a binary bit signal scaled in bits of resolution for one encoder shaft turn.

Also, Incremental encoder tells how fast it is reaching the position whereas Absolute tell the position where it is.

You can also Subscribe to Automation-Talk by Email. for more tutorials or can request one through your comments.

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