PLC Program for Ensuring Sequential Operation of Lubrication and Gear Box Motor.

This is PLC Program for ensuring sequential operation of Lubrication and gear Box Motor

 

Problem Description

In industrial settings, gear box systems often require lubrication before the main gear box motor mechanism can start. Proper lubrication ensures smooth operation and extends the life of the gear box. However, operators may sometimes start the gear box motor without initiating the lubrication process, leading to potential damage and reduced efficiency. This PLC program aims to implement a conditional logic circuit that ensures the lubrication system is activated before the gear box motor can start.

Problem Diagram:-

Solution Overview

To address this problem, we will implement a simple conditional logic example. In this setup, there is one gear box motor that requires lubrication before it can start.

Lubrication System:

We have a lubrication motor that supplies lubrication oil to the main motor or gear box motor.

An interlock system will be put in place to prevent the operator from directly operating the main motor.

Sequential Operation:

The operator must first switch on the oil pump (lubrication motor) before being able to operate the main motor. This system ensures the gear box motor is well-maintained and can operate for a longer time.

Operator Controls:

The operator can start/stop the oil pump using dedicated start and stop push buttons for the oil pump. The main motor can also be controlled by its own start and stop push buttons.

Separate Push Buttons:

We will provide separate push buttons for each motor to ensure clear and independent control.

This approach ensures the gear box motor is always lubricated before operation, thereby protecting the motor and extending its lifespan.

 Program

Here is the PLC program for the conditional control circuit, along with a detailed program explanation.

List of Inputs/Outputs

Inputs List:

• Oil Pump Start Push Button: I0.0
• Oil Pump Stop Push Button: I0.1
• Main Motor Start Push Button: I0.2
• Main Motor Stop Push Button: I0.3

Outputs List:

• Oil Pump Motor: Q0.0
• Main Motor: Q0.1

Ladder diagram for Ensuring Sequential Operation of Lubrication and Gear Box Motor.

Detailed Program Explanation

Network 1

Starting the Oil Pump:Use a Normally Open (NO) contact for the oil pump start push button (I0.0). Include a NO contact of the oil pump (Q0.0) coil for latching the coil.

Stopping the Oil Pump: Use a Normally Closed (NC) contact of the oil pump stop push button (I0.1) in series to unlatch the circuit. Pressing the oil pump stop push button (I0.1) will stop the oil pump (Q0.0).

Network 2

Starting the Main Motor: Use a NO contact for the main motor start push button (I0.2). Include a NO contact of the main motor coil for latching the main motor (Q0.1).

Stopping the Main Motor: Use a NC contact of the main motor stop push button (I0.3) in series to unlatch the circuit. Pressing the main motor stop push button (I0.3) will stop the main motor (Q0.1).

Interlocking: Place a NO contact of the oil pump (Q0.0) in series with the main motor start push button (I0.2). This ensures that the operator must start the oil pump (Q0.0) before they can start the main motor (Q0.1).

 

By following this logic, the oil pump must be activated before the main motor can start. This ensures the gearbox motor is properly lubricated before operation, reducing the risk of damage and prolonging the life of the motor. Operators control the system using dedicated start and stop push buttons for both the oil pump and the main motor, with an interlock to enforce the correct operational sequence.

 

 

Unleashing the Power of Programmable Logic Controllers

Introduction:

Programmable Logic Controllers (PLCs) have revolutionized industrial automation, enabling efficient control and management of complex processes. At the core of every PLC lies its memory, a crucial component responsible for storing and executing programs that drive all automation functions. This article dives into the world of PLC memory, exploring its types, functions, and the technological advancements that have transformed industrial operations.

 

Types of PLC Memory:

PLC memory comprises several distinct types, each serving a specific purpose. These include:

Read-Only Memory (ROM): Non-volatile memory that stores the PLC's firmware and cannot be altered by the user.

Random Access Memory (RAM): Volatile memory used for storing program instructions and data during runtime.

Electrically Erasable Programmable Read-Only Memory (EEPROM): Non-volatile memory permitting limited user modifications, often utilized for storing critical configuration and parameter data.

Flash Memory: Non-volatile memory used for storing larger program sizes and frequently updated data.

Functions of PLC Memory:

PLC memory performs critical functions that enable seamless operation of industrial automation systems:

Program Storage: PLC memory stores the user-defined program instructions, ladder logic, or other programming languages required to control and monitor automated processes.

Data Storage: PLCs utilize memory to store real-time data, inputs, outputs, and variable values essential for efficient decision-making and process control.

 

Retention: Some PLC memory types, such as EEPROM or battery-backed RAM, offer data retention even during power outages, safeguarding vital data and system configurations.

Advancements in PLC Memory Technology:

 

With advancing technology, PLC memory has evolved to meet the needs of modern industrial processes. Some significant developments include:

 

Increased Capacity: The ever-growing memory capacity of PLCs allows for complex program storage, intricate control algorithms, and extensive data logging, facilitating advanced automation functions.

 

Faster Access Speeds: PLC memory has progressed to provide faster access speeds, enabling real-time processing and rapid execution of control functions.

 

Redundancy and Fault-Tolerance: Modern PLCs often incorporate redundant memory systems, ensuring data integrity and fault tolerance in critical applications.

 

Best Practices for Managing PLC Memory:

Effectively managing PLC memory is vital for reliable and efficient system performance. Here are some best practices to consider:

 

Optimize Program Size: Efficient coding techniques, modular programming, and minimizing unnecessary instructions help optimize memory utilization, ensuring efficient execution of program logic.

 

Regular Backups: Regularly backing up PLC memory data and program configurations mitigates the risk of data loss and facilitates faster recovery in the event of a failure or fault.

Memory Monitoring: Monitoring memory usage helps identify potential issues such as memory leaks or excessive memory usage, enabling proactive measures to maintain system performance.

 

 

Explain IN Range instruction or value within range instruction using example

Explain IN Range instruction or value within range instruction using example

Application:-Explain IN_RANGE instruction using an example . Write PLC program for explanation using ladder diagram language in the Programmable Logic Controller (PLC).

Components:-Programmable logic controller, HMI panel, wires, 24 VDC lamp, 24 VDC power source, 24VDC temperature controller.

 

Diagram:-

Explanation:-

We can use IN_RANGE (Value within range) instruction when the variable is within a specific range. You can specify the value range for the MIN and MAX inputs. The IN_RANGE instruction will compare the variable value with the values of MIN and MAX value and sends the result.

For an explanation, we can consider a simple example so we can understand easily. Assume one application in which we need to operate a green lamp if the actual temperature is between MIN and MAX value which can be set by HMI. And if the actual temperature is not between MIN and MX value, operate a red lamp as shown in the figure. Assume analog scaling of the temperature value, so as sown in figure measured value s 50 degrees and MIN limit is 45 degree and MAX degree is 55 degree. So for the above example temperature is within range and the green lamp should be ON.

PLC program:-

Write the ladder program for the above application using ladder diagram language. Here for ladder logic, we can use any supported PLC system like S7-1200, S7-300, S7-1500, or any other PLC which can support this instruction. For PLC logic we need digital inputs and outputs.

For our application lamps are digital outputs. MAX and MIN values are input words.

Digital Output:-

Temp OK lamp=Q0.0

Temp not ok Lamp=Q0.1

M Memory:-

Actual temp. =MW2

MIN temp.:-MW10

MAX temp:-MW20

PLC program Explanation:-

In network 1, actual temperature is measured or stored in MW 2 and in MIN we can set minimum range of the temperature also in MAX we can specify the maximum applicable range of the temperature.

So here we have used IN_RANGE instruction which will compare a variable with MIN and MAX values and if the variable value is within range, green lamp (Q0.0) will be ON and if not then red lamp (Q0.1) will be ON as shown in network 2.

Difference between discrete signals and analog signals:-

Digital Signal:-

Discrete (digital) signals behave as binary switches, yielding simply an ON or OFF signal (1 or 0, True or False, respectively).

Examples of digital signals:-Push buttons, limit switches, and photoelectric sensors are examples of devices providing a discrete signal.

Discrete signals are sent using either voltage or current, where a specific range is designated as ON and another as OFF.

For example, a PLC might use 24 V DC I/O, with values above 22 V DC representing ON, values below 2VDC representing OFF, and intermediate values undefined. Initially, PLCs had only digital I/O.

Analog Signal:-

Analog signals are like volume controls, with a range of values between zero and full-scale.

These are typically interpreted as integer values (counts) by the PLC, with various ranges of accuracy depending on the device and the number of bits available to store the data.

As PLCs typically use 16-bit signed binary processors, the integer values are limited between -32,768 and +32,767.

Examples of analog signal:-Pressure, temperature, flow, and weight are often represented by analog signals.

Analog signals can use voltage or current with a magnitude proportional to the value of the process signal. For example, an analog 0 to 10 V or 4-20 mA input would be converted into an integer value of 0 to 32767.

Current inputs are less sensitive to electrical noise (e.g. from welders or electric motor starts) than voltage inputs.

ON/OFF PLC Output with Switch using S7-1200 PLC

Explanation:-

When Start switch (SW1) will be pressed then Output (Lamp 1) will be on and Output (Lamp 1) will be turned off if switch will be turned off.

Program:- Write the ladder Logic for Above application.
Input List:
Start Switch-I0.0

Output List:
Lamp 1 -Q0.0

ON/OFF PLC Output with Switch using S7-1200 PLC

Explanation:-

When Start switch (SW1) will be pressed then Output (Lamp 1) will be on and Output (Lamp 1) will be turned off if switch will be turned off.

Program:- Write the ladder Logic for Above application.
Input List:
Start Switch-I0.0

Output List:
Lamp 1 -Q0.0

Motor Start/Stop operation with trip indication lamp

Application:-There is one machine in the factory, we want to start/stop motor using push button g from the panel. Give motor ON lamp and motor trip lamp on the panel. When motor is running ON lamp should be ON and if motor trip due to some problem, trip lamp should be ON. Write the PLC program in LAD and FBD language.

Solution:-Here we will make PLC program in the PLC so operator can operate motor from the panel and get indication on the panel. And also we will take inputs signal and outputs for our application

Diagram:-

 

PLC Program:-Write the PLC program from above application using LAD diagram language.

PLC program explanation:-

As per our application we wrote PLC program. In this program we have considered following inputs and outputs for our application. We can use any make PLC for our application.

Inputs:-

Start Button:-I0.0

Stop Button:-I0.1

Trip Input:-I0.2

Outputs:-

Motor:-Q0.0

Motor On Lamp: Q0.1

Trip Lamp:-Q0.2

Network 1:-In this network we are starting and stopping motor by push button. By pressing Start (I0.0) motor can be started and by pressing stop PB (I0.1), motor (Q0.0) can be stopped.

Network 2:-In this network we wrote the logic for motor ON lamp or indication (Q0.1). SO when motor is running, Motor ON lamp is also ON.

Network 3:-For safety purpose we have considered here trip lamp (Q0.2). So when trip signal (I0.2) is ON, trip lamp is also ON.