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System Engineering Ltd


An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits. An inverter is essentially the opposite of a rectifier.

Static inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.

The electrical inverter is a high-power electronic oscillator. It is so named because early mechanical AC to DC converters was made to work in reverse, and thus was “inverted”, to convert DC to AC.


1.1 DC power source utilization
1.2 Uninterruptible power supplies
1.3 Induction heating
1.4 HVDC power transmission
1.5 Variable-frequency drives
1.6 Electric vehicle drives
1.7 Air conditioning
1.8 The general case
1.9 Warnings

In this report contains only the variable frequency inverter or drive. A variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters.

A PLC (Programmable Logic Controller) is a device that was invented to replace the necessary sequential relay circuits for machine control. The PLC works by looking at its inputs and depending upon their state, turning on/off its outputs. The user enters a program, usually via software, that gives the desired results. A programmable logic controller is currently defined by National Electrical Manufacturers Association of America as a digital electronic device that uses a programmable memory to store instruction to implement specific functions such as logic, sequence, timing, counting and arithmetic to control machines and processes. At beginning of its invention and application (during 1980’s) it was the replacement of conventional sequence system such as electromechanical relays, timers, counters and so on. But now a day it is using for automation of equipment as well as for automation of industrial plant as a whole, monitoring and control of all process variables, data acquisition and analysis, production monitoring and forecasting, trouble shooting of equipment and so on.

Broad Objective:

The broad objectives of this report are mainly understood the servicing and maintenance of Variable frequency inverter and PLC.

Specific Objectives:

1. Study on Variable frequency inverter and PLC.
2. Identifying different types of Variable frequency inverter and PLC.
3. Suggest probable solution of the identified problem.


• Both primary and secondary data are being collected for the purpose of this report. The report is concentrated of the technical support service and maintenance of variable frequency inverter and PLC.
• Primary Data are collected from the maintenance Chart, the User Manual handbooks and Text books.
• Secondary data are being collected from the printed Journals, brochures and websites.

1.1 Background:

System Engineering Ltd is one of the most reputed organizations in Bangladesh kind of for different Industrial Automation works, Electro-Mechanical & Electrical Engineering works, Plant Election & maintenance, Man-Machine Customization etc. Its objective is to help to make maximum return from the system. It has self-supported expertise technical teams with modern tools & technology.

System Engineering Ltd is authorized sole-agent of some world-class manufacturers in Bangladesh. SEL has selected these companies for their high quality products with justified price for Bangladesh. SEL thinks, high quality products & services are the most important factors to our industrial sector for developing our country.

Our outlook is totally different. We were born differently. We are growing with a different view. We are stuffed with courteous, responsive, dependable professionals, who are able to provide a variety of services.

The company enjoys good reputation due to its quality product sales and after sales services, innovation, productivity and customer support. The company is looking forward to providing with efficient customer service, support and better technology to the local market.

1.2 List of Services:

• Plant Erection & Maintenance
• Trouble Shooting & Up gradation of Industrial Machinery
• Man-Machine Customization
• Electrical LT Panel, MCC Panel, PFI Panel Fabrication
• Pipe-Line and Cable Work
• Duct Fabrication

List of products:

PLC LS Korea ABB Finland
Touch Screen & XGT Panel LS– Korea ABB–Finland
Electric Motor ABB – India
Name of Organization System Engineering Ltd Hyundai – Korea
Year of Establishment 2000
Earlier/Old Name System Automation (Till 2007)
Type of Business Plant Erection on turnkey basic
Selling of Automation Products
Selling of Low & Medium Voltage Products
Partnerships Distributor of LS, Korea (Old name of LG) for automation products
Channel Partner of ABB, Finland for Inverter, PLC, Electric Motor and Instruments
Sole-Agent of Autonics, Korea for Sensor and Controllers
Exclusive distributor of Hyundai, Korea for low and medium volt electric products
Employees 63 employees
Address House # 53, Road # 03, Sector # 3, Uttara, Dhaka – 1230
House # 15, Road # 18, Sector # 3, Uttara, Dhaka – 1230

1.4 History

Year Activities
2000 Three dynamic engineers formed a company named System Automation for Plant Erection, Maintenance & Trouble Shooting.
2001 Joined with LG as Local Distributor in Bangladesh at Sep’2001 for their industrial automation products.
2003 Successfully completed our first plant erection project on Battery Manufacturing Plant of Rahimafrooz, Zirani Bazar, Savar, Dhaka which they started at 2001 and capacity was 1,50,000 battery/month.
2004 Joined with Autonics Corporation as their Sole-Agent in Bangladesh.
2006 Successfully completed plant erection of Global Dyeing & Spinning Mills Ltd at Rupgonj, Narayangonj.
2007 Became a Limited company and changed its name to “System Engineering Ltd”.
2007 Joined with Hyundai as their Exclusive Distributor in Bangladesh for their LV & MV products.
2008 Joined with ABB as their Channel Partner in Bangladesh for their Inverter, PLC, Electric Motor and Instruments.
2008 Started Battery Manufacturing Plant erection project of Rahimafrooz (10,00,000 battery/month) at Iswordi EPZ (running).
2008 Started erection project of Battery Accumulator Plant of Rahimafrooz at Saver (running).

1.6 Vision

The vision of system Engineering Ltd is to become the country leader for industrial solutions and establish ourselves as the largest and most lucrative service provides in our country.

1.7 Mission

System Engineering Ltd. has acknowledged the responsibility to eradicate the deficit in country’s industrial automation equipment service and to improve the quality of the lives of their employees and the communities they serve. The company aims to achieve this mission not only through best quality products but also through excellence in service.

1.7 Theme

System Engineering Ltd. Always said as their theme “Best service way of progress”. They also use this theme beside their logo.

1.8 Quality Commitment
System Engineering Ltd .has acknowledged the responsibility to eradicate the deficit in country’s Industrial automation equipment Industrial automation equipment and to improve the quality of the lives of their employees and the communities they serve. The company aims to achieve this mission not only through best quality products but also through excellence in its service.
The goal of System Engineering Ltd. is to become best electro-mechanical firm in Asia by achieving excellence in all facets of its activities. System Engineering Ltd. believe that with strong dedication, their continued research on quality control and their commitment to ‘Just in Time’ delivery and quality after sales support will certainly lead them to our goal.
Their various quality policies involve employing fully qualified experienced engineers some are foreign trained, carrying on regular inspection of their equipments by both local and foreign renowned experts, providing full time training to their newly recruited employees and sharing their ideas. System Engineering Ltd. emphasize greatly on after sales care. With a 12-member team of experienced teams and graduate engineers in charge of support and service department are available even during non working hours, System Engineering Ltd. believe that they serve the customers with the best quality commitment System Engineering Ltd. is proud to declare that their quality management system is better then others company.

1.9 Uncompromising Integrity

Reputation of System Engineering Ltd. is based upon their ability to fulfill promises to shareholders, customers and employees. They do so by being honest in their dealings, taking responsibility and being accountable for their actions. System Engineering treats everyone the way they would like to be treated. They are proactive in identifying issues and coming up with solutions. They ensure that the highest ethical standards guide in making decisions. System Engineering is true to our word.

1.10 Respect & Care for Others

By working as one team with shared goals System Engineering Ltd. achieve great things. They value ideas and contributions from everyone. System Engineering recognize, respect and value diversity in the team. They develop strong bonds by communicating and sharing knowledge. They encourage open discussion and commit to an agreed position.

System Engineering Ltd. has implemented a Quality Management System that is continuously maintained for effectiveness and process improvements in accordance with the requirements of clients.

2.1 The Process Approach

In accordance with the requirements of the standard, EEL has adopted a process approach in design of quality management system.

The processes as applicable and relevant to EEL has been identified and defined. Output of every process is input to one or more processes. In case the output is not flowing to any internal of the processes, it flows to customers and other interested parties. Thus input to every process is outcome of one or more processes. In case input is not being derived from any internal process, the same flows from customers and other interested parties or from external sources.
Methods have been defined to ensure that operation and control of these processes are effective and efficient. Resource requirements for each of the processes are assessed by management to ensure that operation and monitoring of the process can be done as planned.

Strong monitoring, measurement and analysis of the process has been defined as a support process to ensure process performance and is measured and communicated at regular intervals within the organization. Based on the results, action plans are developed for implementing actions necessary for improvement of the processes.

2.2 Product Realization Processes:

1. Order Bagging (Institutional)
2. Forecasting
3. Planning
4. Product Development
5. Procurement
6. Manufacturing
7. Dispatch & Installation
8. Maintenance
9. Customer Complaint Handling

2.3 Measurement, Analysis and Improvement Processes:

• Measurement and Monitoring
• Customer Satisfaction Measurement

2.4 Top Management Process:

Management Review

Figure: Organization overview

2.5 Sequence and Interaction Process

Product Realization Processes:

Past Years Performance Results From other External Sources

Chapter One

1.2 Block diagram of PLC :

Reference LG Manual book.

Fig-2: Bolck diagram of PLC

Fig-3: Input and Output of PLC

Fig-4: Structure of PLC

Fig-5: PLC Processor

Fig-6: PLC I/O Port

1.3 PLC I/O Configuration

1.4 PLC I/O Configuration

Figure of PLC module

1.5 Programming Device

1.6 Advantage of a PLC Control System

Fig-7: Ladder diagram

Fig-9: Electro magnetic relay

Fig-9: PLC Communication system

Fig-10: PLC machine control system

1.7 Difference from a pc

Fig-11: PLC

1.8 PLC Programming

1.9 Symbol of ladder logic

1.10 Process of programming

1.11 Control panel with a PLC controller

With invention of programmable controllers, much has changed in how an process control system is designed. Many advantages appeared. Typical example of control panel with a PLC controller is given in the following picture.

Fig-12: PLC Control System Panel Board.

1.12 Advantages of control panel that is based on a PLC controller can be presented in few basic points:

Compared to a conventional process control system, number of wires needed for connections is reduced by 80%
Consumption is greatly reduced because a PLC consumes less than a bunch of relays
Diagnostic functions of a PLC controller allow for fast and easy error detection.

Change in operating sequence or application of a PLC controller to a different operating process can easily be accomplished by replacing a program through a console or using a PC software (not requiring changes in wiring, unless addition of some input or output device is required).

Needs fewer spare parts
It is much cheaper compared to a conventional system, especially in cases where a large number of I/O instruments are needed and when operational functions are complex.
Reliability of a PLC is greater than that of an electro-mechanical relay or a timer.

PLC Communication

A: It depends on the two devices being connected, whether they are DTE or DCE devices, how they are connected together before adding a RS-232/RS-422 Converter, how many signal lines are required. This information is for devices requiring only Receive (Rx) and Transmit (Tx) signal only, other devices require more connection pairs.

A1: CASE #1: The Device connects directly to the serial port on the Computer. The computer serial port is configured as a DTE port, the device cabling is configured as DCE to connect directly. With this connection, the first RS-422 converter connects with a Standard serial cable wired pin #1 to #1, #2 to #2, etc. The second converter requires a null modem connection between it and the device, since our converter is configured as DCE on the RS-232 side, and the device cabling is also DCE. See the connection diagram for CASE #1.

Fig-13: PLC Communication
A2: CASE #2: The Device connects through a Null Modem (Crossover) Cable to the serial port on the Computer. This original connection requires a Null Modem cable because both Computer and Device are configured as DTE. In this case, the first RS-422 Converter connects to the Computer with a Standard serial cable wired pin #1 to #1, #2 to #2, etc. The original Null Modem Cable is set aside, not used. A new Standard serial Cable is connected to the device and the second converter. See the connection diagram for CASE #2.

A3: CASE #3: In the third case, we want to extend a set of RS-232 connections between two devices, but we don’t know how either port is configured. Both devices use DB9F (female) connectors. We have a voltmeter. We know the converters are DCE devices. When powered, the RS-232 output will have a negative DC voltage compared to GND. So, we connect a Standard cable to the device, power it up, measure between Pin #5 of the cable to Pin #3. If it has a minus voltage (usually between -3VDC to -11VDC), connect it to the DB9 connector of the converter. This connection should be okay. If almost no voltage on Pin #3, check Pin #2. If it has the minus voltage, use a Null Modem Connection between the device and converter to swap the pin connections. If neither has a voltage, you need pinouts for the connector/cable. Make a similar test for the RS-232 connections at the other end. The voltage should be on the cable pin connecting to Pin #3. No Connection diagram for CASE #3, it will either match CASE #1 or CASE #2, but could instead require connections with Null Modem Connections on both converters if the original cable is not used.
The pin numbers for the RS-422 connections are not shown, they may vary according to the model, but the signal name will be shown on the data sheet.
In the case of DB25 RS-232 connections, Pin #2 is TD, Pin #3 is RD, and Pin #7 is GND.

Note: These connection figures do not show power supplies or handshaking lines needed to power “port powered” converters. The port powered devices usually need the RTS line and DTR line high (signal level +11 VDC), a power supply may be required for both ends if the RS-422 transmitter voltage is less than 4.4 volts TD(B) to TD(A). For pin outs of RS-232, refer to the FAQ on RS-232 Connections that WORK!
RS-232 Facts
RS-232 is a point-to-point serial communications standard that defines the electrical and mechanical details of the interface between Data Terminal Equipment (DTE) and Data Communications Equipment (DCE). Compared with newer standards RS-232 is limited in terms of data rate, maximum distance and noise immunity. The standard defines 25 electrical connections including data lines, control (hardware handshake) lines, timing lines and special secondary function lines. In typical applications many of these lines are not used.
Cables: When connecting a DTE to a DCE all connections are straight through. When connecting a DTE to a DTE a special ‘null modem’ or crossover cable is required.
Connectors: The original RS-232 connector was a DB-25, which supported all RS-232 lines. Often, DB-9 connectors are used, which support the most common data and hardware handshake lines.
Speed/Distance: The standard suggests RS-232 can operate at about 20 kbps over distances of 50 feet, a conservative estimate depending on grounding and noise considerations. Over short distances RS-232 is sometimes operated at rates as high as 115.2 kbps. Several hundred feet is possible at data rates of 9600 bps or lower.
Tech Tip: For longer distances, higher speeds and more noise immunity, convert to RS-422 for point-to-point, or RS-485 for multi-drop applications.



DB9-Female To DB9-Male or Terminal



DB9-Female to DB9-Male or Terminal
RS232 serial cable layout

Almost nothing in computer interfacing is more confusing than selecting the right RS232 serial cable. These pages are intended to provide information about the most common serial RS232 cables in normal computer use, or in more common language “How do I connect devices and computers using RS232?”
RS232 serial connector pin assignment

The RS232 connector was originally developed to use 25 pins. In this DB25 connector pin out provisions were made for a secondary serial RS232 communication channel. In practice, only one serial communication channel with accompanying handshaking is present. Only very few computers have been manufactured where both serial RS232 channels are implemented. Examples of this are the Sun SPARCstation 10 and 20 models and the Dec Alpha Multia. Also on a number of Telebit modem models the secondary channel is present. It can be used to query the modem status while the modem is on-line and busy communicating. On personal computers, the smaller DB9 version is more commonly used today. The diagrams show the signals common to both connector types in black.

The defined pins only present on the larger connector are shown in red. Note, that the protective ground is assigned to a pin at the large connector where the connector outside is used for that purpose with the DB9 connector version.
The pin out is also shown for the DEC modified modular jack. This type of connector has been used on systems built by Digital Equipment Corporation; in the early day’s one of the leaders in the mainframe world. Although this serial interface is differential (the receive and transmit have their own floating ground level which is not the case with regular RS232) it is possible to connect RS232 compatible devices with this interface because the voltage levels of the bit streams are in the same range. Where the definition of RS232 focused on the connection of DTE, data terminal equipment (computers, printers, etc.) with DCE, data communication equipment (modems), MMJ was primarily defined for the connection of two DTE’s directly.

RS232 DB9 pinout

DEC MMJ pinout

RS232 DB25 pinout

RS232 DB25 to DB9 converter

The original pinout for RS232 was developed for a 25 pins sub D connector. Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. In mixed applications, a 9 to 25 pins converter can be used to connect connectors of different sizes. As most of the computers are equipped with the DB9 serial port version, all wiring examples on this website will use that connector as a default. If you want to use the example with a DB25, simply replace the pin numbers of the connector according to the conversion table below.

RS232 DB9 to DB25 converter

DB9 – DB25 conversion
DB9 DB25 Function
1 8 Data carrier detect
2 3 Receive data
3 2 Transmit data
4 20 Data terminal ready
5 7 Signal ground
6 6 Data set ready
7 4 Request to send
8 5 Clear to send
9 22 Ring indicator

RS232 serial loopback test plugs

The following RS232 connectors can be used to test a serial port on your computer. The data and handshake lines have been linked. In this way all data will be sent back immediately. The PC controls its own handshaking. The first test plug can be used to check the function of the RS232 serial port with standard terminal software. The second version can be used to test the full functionality of the RS232 serial port with Norton Diagnostics or Check It.

DB9 DB25 Function

1 + 4 + 6 6 + 8 + 20 DTR
2 + 3 2 + 3 Tx
7 + 8 4 + 5 RTS

Testing occurs in a few steps. Data is sent on the Tx line and the received information on the Rx input is then compared with the original data. The signal level on the DTR and RTS lines is also controlled by the test software and the attached inputs are read back in the software to see if these signal levels are properly returned. The second RS232 test plug has the advantage that the ring-indicator RI input line can also be tested. This input is used by modems to signal an incoming call to the attached computer.

RS232 null modem cables

The easiest way to connect two PC’s is using an RS232 null modem cable. The only problem is the large variety of RS232 null modem cables available. For simple connections, a three line RS232 cable connecting the signal ground and receive and transmit lines is sufficient. Depending of the software used, some sort of handshaking may however be necessary. Use the RS232 null modem selection table to find the right null modem cable for each purpose. For a Windows 95/98/ME Direct Cable Connection, the RS232 null modem cable with loop back handshaking is a good choice.
RS232 null modem cables with handshaking can be defined in numerous ways, with loopback handshaking to each PC, or complete handshaking between the two systems. The most common null modem cable types are shown here.
Simple RS232 null modem without handshaking (Null modem explanation)

Connector 1 Connector 2 Function
2 3 Rx
3 2 Tx
5 5 Signal ground

RS232 null modem with loop back handshaking (Null modem explanation)

Connector 1 Connector 2 Function
2 3 Rx
3 2 Tx
5 5 Signal ground
1 + 4 + 6 – DTR
– 1 + 4 + 6 DTR
7 + 8 – RTS
– 7 + 8 RTS

RS232 null modem with partial handshaking (Null modem explanation)

Connector 1 Connector 2 Function
1 7 + 8 RTS2
CTS2 + CD1
2 3 Rx
3 2 Tx
4 6 DTR
5 5 Signal ground
6 4 DSR
7 + 8 1 RTS1
CTS1 + CD2

RS232 null modem with full handshaking (Null modem explanation)

Connector 1 Connector 2 Function
2 3 Rx
3 2 Tx
4 6 DTR
5 5 Signal ground
6 4 DSR
7 8 RTS
8 7 CTS

1.12 PC to RS485 Interface


Figure 1: Circuit Diagram of Isolated RS485 Interface

Figure 1 shows the circuit diagram of RS485 interface. Connector K1 is linked to the serial port of the PC, power to the PC side of the circuit is derived from the signal lines DTR and RTS. Positive supply is derived from RTS and negative supply from the DTR line. The RTS line is also used to control the data direction of RS485 driver IC U4.

Optical isolation is achieved by optocouplers U1, U2 and U3. Opto U1 is used to control the data direction of U4 opto U2 provide RXD line isolation while opto U3 provide TXD line isolation.
The other side of the isolator carries TTL levels. This side is powered by an unregulated dc supply between 9V and 18V dc. IC U5 provide 5V regulated output and IC U4 provide the RS485 bus interface. The TXD and RXD lines status are provided by data indicating LEDs. The interface has been tested at the baud rate of 19.2k baud.
For Data Reception RTS = 1 (at +ve level)
For Data Transmition RTS = 0 (at -ve level)
DTR line is always set to 0 (at -ve level)

Figure 2 & 3 shows the component layout of the isolator pcb and the track patterns respectively.

Fig-15: Component layout of the Isolator PCB

Figure 16: Track patterns of the Isolator PCB

Component details of the project.
1 4 C1,C2,C3,C6 100nF

2 1 C4 10uF 16V

3 1 C5 470uF 25V

4 3 D1,D2,D3 1N4148

5 2 D4,D5 LED RED 3mm

6 2 D7,D6 TRANSIL 6.8V

7 1 D8 1N4003



10 3 R1,R2,R3 1K8

11 2 R7,R4 4K7

12 2 R5,R8 1K

13 3 R9,R12 150R

14 1 R6 680R

15 2 R11,R10 10R

16 1 R13 120R



19 1 U4 MAX487, SN75176B

20 1 U5 LM7805

PLC programming cables for several brands

Most PLC’s can be programmed from a PC via a serial cable. Unfortunately, many of these cables have a non standard layout. De cables shown here can be bought from the regular sales channels, but it is often much cheaper to solder them yourself.

Mitsubishi PLC cable layouts

Melsec PLC’s from Mitsubishi can be connected to PC’s running Medoc programming software using various cables. Each different I/O module uses a different pin assignment.

Not all Mitsubishi PLCs can be connected directly to a programming PC. The signal levels of the A series CPU units are not RS232 compatible and must be converted with a SC-02N or SC-05 converter. The serial cable layout to connect this converter to a PC is shown in this diagram.

PC to Mitsubishi SC-02N/SC-05 adapter cable

If more than one serial port is necessary on an A series melsec PLC, the AJ71C24 or AJ71C21 serial communication modules can be plugged into the system. These modules provide RS232 compatible serial ports, so no signal conversion is necessary to connect these modules with a PC. Both modules are equipped with a DB25 connector. The cable layout for these two modules is shown below.

PC to Mitsubishi AJ71C24 serial programming cable

PC to Mitsubishi AJ71C21 serial programming cable

The A1SJ71C24-R2 can also be used to connect computers and devices to a melsec series A PLC. This plug-in module contains two serial ports, each with a DB9 connector. The wiring layout is in fact identical to the

PC to Mitsubishi A1SJ71C24-R2 serial programming cable

Omron PLC cable layouts

The PLC’s from Omron can be connected to various peripheral equipment. Each device requires its own cable layout. Only the more common cables are shown here.

DB9 RS232 programming cable

DB25 RS232 programming cable

CV500-CIF01 tool bus programming cable

Siemens PLC’s

Most programming of Siemens S5 PLC’s is done using a special RS232 to TTY converter. The S7 series are programmed using a RS232 to MPI bus converter. The easiest thing to do is buy these special cables from your local Siemens supplier. The operator terminals however can be programmed using a normal serial cable. The following cable can be used to program the OP series of operator displays.

Programming cable for OPxx display series

Systematic approach to designing a process control system

first, we need to select an instrument or a system that you wish to control. Automated system can be a machine or a process and can also be called a process control system. Function of a process control system is constantly watched by input devices (sensors) that give signals to a PLC controller. In response to this, PLC controller sends a signal to external output devices (operative instruments) that actually control how system functions in an assigned manner (for simplification it is recommended that we draw a block diagram of operations’ flow).

Secondly, we need to specify all input and output instruments that will be connected to a PLC controller. Input devices are various switches, sensors and such. Output devices can be solenoids, electromagnetic valves, motors, relays, magnetic starters as well as instruments for sound and light signalization.

Following an identification of all input and output instruments, corresponding designations are assigned to input and output lines of a PLC controller. Allotment of these designations is in fact an allocation of inputs and outputs on a PLC controller which correspond to inputs and outputs of a system being designed.

Thirdly, should make a ladder diagram for a program by following the sequence of operations that was determined in the first step.

Finally, program is entered into the PLC controller memory. When finished with programming, checkup is done for any existing errors in a program code (using functions for diagnostics) and, if possible, an entire operation is simulated. Before this system is started, we need to check once again whether all input and output instruments are connected to correct inputs or outputs.

Maintenance Part

Fig-17: Font view of plc

Fig-18: Power Circuit of PLC

Fig-19: Control circuit of PLC
Power Failure

Power section of PLC fault occurred.
Replace capacitor

Economical Benefit Using a PLC Control Panel Board

Increased production
Improved quality
Greater product uniformity
Saving in raw materials
Saving in energy
Saving in manpower
Increase safety

Chapter Two

2.1 Introduction

An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits. An inverter is essentially the opposite of a rectifier.
Static inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries.

Inverter designed to provide 115 VAC from the 12 VDC source provided in an automobile. The unit shown provides up to 1.2 amperes of alternating current, or just enough to power two sixty watt light bulbs.
An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage.

Grid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout.
Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid

A variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters.

2.2 Main part of inverter
Input Section
Control Section
Power Section
Output Section

Input section
There are many parts of input section
Breaking resistor
Health relay

Control Section
There are three types of control
Key pad

Power Section
Main parts of power Section
SMPS card

Output Section
DC Converter
Chopper transformer

Operation mode
Frequency reference mode
Keypad mode
Terminal mode
Communication mode
Input function

Analog input
Variable pot, Terminal RS232
ACC-Accelerations time
DEC-De acceleration time
Base frequency
Maximum frequency

Digital input
Multifunction 1
Multifunction 2
Multifunction 3

2.3 Inverter Specification
kW/Voltage Ratings:

o 0.75 ~ 55kW, 3 phase, 200 ~ 230VAC

o 0.75 ~ 75kW, 3 phase, 380 ~ 480VAC

– Selectable V/f, Sensor less vector, Sensor vector control (Optional)

– Built-in process PID control

– Optimum acceleration & deceleration for a maximum torque

– APP parameter group for special operations;

Traverse, Multi Motor Control, DRAW

– Multi-function I/O terminal:

Input: 27 functions / Output: 21 functions

– Multi Motor Control (Up to 4 motors: Optional)

– Motor parameter Auto-tuning

– Parameter Read/Write function using a detachable LCD Keypad

Fig-20: Inverter iG5A-4

– Power terminal configuration

Symbols Functions

R AC Line input (3 Phase 200-230 VAC or 380-460 VAC)



G Earth Ground

U 3 Phase power output terminal to motor (3 Phase 200-230 VAC or 380-460 VAC)



G Earth Ground

P1 Positive DC bus terminal
External DC Reactor connection terminal and DB Unit connection terminal

LS Starvert iG5A is very competitive in its price and its functional strength compared to iG5. User-friendly interface, extended inverter ranges up to 7.5kW, superb torque competence and small size of iG5A provides an optimized user environment.
Selectable V/f, sensor less vector control

– Motor parameter Auto-tuning

– Powerful torque at overall speed range

– 0.1 ~ 400Hz frequency output

– -15% ~ +10% input voltage margin

– Fault history: Last 5 faults

– 0~10Vdc / -10 ~ +10Vdc analog input

– IP20 enclosure, UL Type 1 (Option)

– Selectable manual/automatic torque boost

– Selectable PNP/NPN input signal

– 2nd motor control and parameter setting

– Built-in Dynamic braking transistor as standard

– Enhanced process PID control

– Built-in RS485 (LS Bus / Modbus RTU) communication

– Cooling fan On/Off control & Easy change

– Remote control using external keypad * RJ45 cable (Optional)

– Upgraded functions: Sleep & Wake-up (Energy savings)

KEBKinetic Energy Buffering) protection

Low l (eakage PWM algorism

– Monitoring & commissioning PC based software tool

Starvert iP5A series adopt various functions as standard for operation of Fan and Pump. iP5A’s optimum performance for Fan & Pump, you can optimize system stability in user-environment and reduce system construction cost.

– Dual PID

When additional PID control or Cascade PID control is required, Dual PID provides users various uses of the system with only iP5A.

– Multi Motor Control

The built-in algebra control function enables an inverter to control many motors without a controller so that user can take advantage of energy-saving and cost-down.

– Sleep and Wake-Up

The built-in energy saving function makes inverter stop automatically when the capacity is very low.

– Pre Heater

The pre heater function is built-in to prevent motor damage and inverter break-down caused from humidity.

– Flying Start

When the inverter drives many ventilators or when the fan in a big load system turns due to a natural convection, iP5A operates the motor by searching the motor speed automatically.

– Auto energy saving

iP5A provides the auto energy saving function by the optimal flux control which minimizes an energy loss caused by a change of the load.

– Improved Management from Instant Power-off and Power Dip Generation

During the power Dip or instant power-off, which is generated by lightening, ground fault and power-failure, loads still keep the mechanical energy and this energy flows back to inverter by regeneration. The power-failure guarantee time is extended by using this electrical character of inverter.

– Constant and Stable Performance (24 hours 365 days)

Regardless of outside alteration such as input voltage variation by load change or weather effect, iP5A can handle moter and load with best performance.

– Safety Stop

When unexpected power-failure blocks power supply, inverter stops motor by using inertia energy of load that prevents unexpected second accident (Parameter setting is required).

– 200V Class
SV ¡ iP5A – 2 055 075 110 150 185 220 300

Motor Rating1) [HP] 7.5 10 15 20 25 30 40

[kW] 5.5 7.5 11 15 18.5 22 30

Output ratings Capacity[kVA]2) 9.1 12.2 17.5 22.9 28.2 33.5 43.8

Rated current[A] 24 32 46 60 74 88 115

Output frequency 0.01 ~ 120 [Hz]

Output voltage(V) 200 ~ 230V

ratings Voltage[V] 3 Phase 200~230 V (-15% ~ +10%)

Frequency 50 ~ 60 [Hz] (± 5%)

Weight (kg) 4.9 6 6 13 13.5 20 20

– 400V Class

SV iP5A – 4 055 075 110 150 185 220 300

Rating1) [HP] 7.5 10 15 20 25 30 40

[kW] 5.5 7.5 11 15 18.5 22 30

ratings Capacity
[kVA]2) 9.6 12.7 19.1 23.9 31.1 35.9 48.6

current[A] 12 16 24 30 39 45 61

Output frequency 0.01 ~ 120 [Hz]

Output voltage(V) 380 ~ 480V3)

ratings Voltage[V] 3 Phase 380~480 V (-15% ~ +10%)

Frequency 50 ~ 60 [Hz] (± 5%)

Weight (kg) 4.9 6 6 12.5 13 20 20

SV iP5A – 4 370 450 550 750 900 1100 1320

Rating1) [HP] 50 60 75 100 125 150 175

[kW] 37 45 55 75 90 110 132

ratings Capacity
[kVA]2) 59.8 72.5 87.6 121.1 145.8 178 210

current[A] 75 91 110 152 183 223 264

Output frequency 0.01 ~ 120 [Hz]

Output voltage(V) 3 Phase 380~480V3)

ratings Voltage[V] 3 Phase 380~480 V (-15% ~ +10%)

Frequency 50 ~ 60 [Hz] (± 5%)

Weight (kg) 27 27 29 42 43 101 101

SV iP5A – 4 1600 2200 2800 3150 3750 4500

Rating1) [HP] 215 300 350 400 500 600

[kW] 160 220 280 315 375 450

ratings Capacity
[kVA]2) 259 344 436 488 582 699

current[A] 325 432 547 613 731 877

Output frequency 0.01 ~ 120 [Hz]

Output voltage(V) 3 Phase 380~480V3)

ratings Voltage[V] 3 Phase 380~480 V (-15% ~ +10%)

Frequency 50 ~ 60 [Hz] (± 5%)

Weight (kg) 114 200 200 243 280 380

1) Indicates the maximum applicable capacity when using a 4-Pole LG motor.
2) Rated capacity (v 3×V×I) is based on 220V for 200V class and 460V for 400V
3) Maximum output voltage will not exceed the input voltage. An output voltage less
than the input voltage may be programmed if necessary.

specifications Dynamic braking torque Max. braking torque 20% continuous4)

ED Option (braking UNIT, braking resistor) 4)

Cooling method Forced air cooling

Protection degree IP20, UL Enclosed Type 1(provided with conduit box) for all ratings, UL Open type from 15 to 90 kW (Optional conduit plate)

Control Control method V/F, Sensor less Vector, Slip Compensation, Easy Start Selectable

Frequency setting resolution Digital reference: 0.01Hz(Below 100Hz), 0.1Hz(Over 100Hz), Analog reference: 0.01Hz/60Hz

Frequency accuracy Digital: 0.01% of max. output freq
Analog: 0.1% of max. output freq

V/F ratio Linear, Square pattern, User V/F

Overload capacity 110% per 1min, 120% per 1min5)

Torque boost Manual torque boost(0 to 15% adjustable), auto torque boost

Operation Operation method Keypad/Terminal/Communication selectable

Frequency setting resolution Analog:0~12V/-12V~12V/4~20mA/0~20mA/Pulse/Ext-PID, Digital: Keypad

Input signal Start signal Forward, Reverse

Multi-Step Up to 18 Speeds can be set including Jog (Use Programmable Digital Input Terminal)

Multi-Step Accel/Decel time 0.1~ 6,000 sec, Max 4 types can be set via Multi- Function Terminal.
Accel/Decel Pattern: Linear, U-Curve, S-Curve Selectable

Emergency stop Interrupts the Output of Inverter

Jog Jog operation

Fault reset Reset the fault when the protective function is active.

Output signal Operating status Frequency Detection Level, Overload Alarm, Stalling, Over Voltage, Low Voltage, Inverter Overheating/ Running/ Stopping/ Constant running, Inverter By-Pass, Speed Searching

Fault output Contact Output (3A, 3C, 3B) – AC 250V 1A, DC 30V 1A

Indicator Choose 2 from Output Frequency, Output Current, Output Voltage, DC Link
Voltage (Output Voltage: 0 ~ 10V)

Operation function DC Braking, Frequency Limit, Frequency Jump, 2nd Function, Slip Compensation, Reverse Rotation Prevention, Auto Restart, Inverter By-Pass, Auto-Tuning, PID Control, Flying Start, Safety Stop, Flux Braking, Low leakage, Pre-PID, Dual-PID, MMC, Easy Start, Pre-heater

Protection function Inverter trip Over Voltage, Low Voltage, Over Current, Ground Fault , Inverter Overheat, Motor Overheat, Output Phase Open, Overload Protection, External Fault 1, 2, Communication Error, Loss of Speed Command, Hardware Fault, Option Fault, etc

Inverter alarm Stall Prevention, Overload Alarm, Thermal Sensor Fault

Momentary power loss Below 1 sec: Continuous operation, Above 1 sec: Auto restart active when Safety Stop is set to “Yes” with a fan connected.

Keypad Operation information Output Frequency, Output Current, Output Voltage, Frequency Set Value, Operating Speed, DC Voltage, Integrating Wattmeter, Fan ON time, Run-time, Last Trip Time.

Trip information Trips Indication when the Protection Function activates. Max. 5 Faults are saved. Last Trip Time.

Environment Ambient temperature -10¡É~40¡É (use loads less than 80% at 50¡É)

Storage temperature -20¡É~65¡É

Ambient humidity Less than 90% RH Max. (No condensing)

Altitude, Vibration Below 1,000m• Below 5.9m/sec² (=0.6g)

Application site Pollution degree 2, No Corrosive Gas, Combustible Gas, Oil Mist, or Dust


Fig: 21-Inverter IV5

S Starvert iV5 series realizes the high precision vector control in entire operational area and its highly precise speed control guarantees superb control stability in the elevator controls.
Auto tuning
In the application which requires a high torque at low speed, the electrical parameters of motor should be properly set for an optimal operation. Auto tuning function of iV5 make users to set the motor variable accurately.

– various communication interface

iV5 provides various communication interface such as RS 485, Device NET, Profibus-DP and Modbus-RTU.

– Extended function card (ENC_DIV,DIAO and ELIO)

Option card for the encoder pulse division (ENC_DIV) supports the encoder with open collector output and can divide the encoder pulse up to 1/128. Digital input and Analog signal output card (DIAO) can receive the binary speed command from PLC or other upper level controller and has 4 channels of analog signal output. ELIO card enables the lift application software to be available for an optimized lift operation.

Terminal configuration

Power terminal configuration

Symbol Name Description

R,S,T AC Input 3Phase AC input connection
1) 200V: 200~230V, 50/60Hz
2) 400V: 300~460V, 50/60Hz

U,V,W Output Cable connection of 3 phase induction motor

G Earth ground Inverter frame earth terminal

B1,B2 Braking resistor Braking resistor connection

P1,P2 DC reactor and Braking unit DC reactor, braking unit and DC link common connection terminal

P DC Link(+-) terminal DC Link common connection terminal

N DC Link(-) terminal Braking unit and DC link common terminal

Control terminal configuration

Item Display Name Description

Digital input FX Forward run command ‘ON’ when tied to CM terminal

RX Reverse run command Stops when FX, RX are ON / OFF simultaneously

BX Emergency stop ON when closed to CM, FREERUN Stop and Deceleration stop. It does not trigger fault alarm signal.

RST Fault reset Clears the fault condition when the fault state is removed.

P1 Multi-function input terminal Selectable among the following 27 functions:
(Multi step speed selection 1/2/3, JOG run, MOP up/down/Save/Clear, Analog hold, Main drive, Second function, Speed Acc/Dec time selection, 3-wire operation, External default signal B contact point, Forward rotation prevention, Process PI disable, Timer input, Soft start cancellation, ASR PI Gain selection, ASR P.PI selection, Flux reference selection, Pre-excitation, Speed/Torque control selection, Torque limit use, Torque bias







CM COMMON “ON” in case of connection between CM and digital

Analog input VREF Power supply for Analog setting Reference voltage by variable resistor ( + 10V ) : 10k§Ù

AI1 Voltage/ Current Signal Input – Voltage signal input (-10 ~ 10V), current signal input (4 ~ 20mA), Motor NTC selectable via Multi-function Analog input.
– Selectable among following 8 different functions;
Speed/Torque/Flux command, Torque bias, Torque limit,
Process PI controller command, Process PI controller feedback value, Draw command, Motor NTC input)
– Jumper setting in Voltage Input: Closed (Jumper connected as Default)
– AI1, AI2: Open (Jumper disconnected), AI3: Switch set on left side
– Jumper setting in Current Input
– AI1, AI2: Short
– Motor NTC (When using LG-OTIS Motor Only)
– AI3: switch set on right side.


AI3 Voltage/ Motor NTC input

5G COMMON – COMMON terminal for analog input

P5 Power supply for open collector – +5V

5G – 0V

Encored input A+ Encoder A-phase signal – A, B signal for Line Drive Type Encoder.
– Short P5 pin of JP2 on I/O PCB and set JP1 switch to LD for the use of Line Drive.


B+ Encoder B-phase signal


P15 Power supply for open collector + 15 V

5G 0 V

PA Encoder signal output : A-Phase – A, B signal for Complementary or Open Collector Type Encoder.
– Short P15 pin of JP2 on I/O PCB and set JP1 switch to “OC”.

PB Encoder signal output: B-Phase

Analog output AO1 Analog output 1 Output range: -10V ~ +10V
Selectable among 31 (Motor speed, speed ref. 1~2, Torque command 1~2, torque current, flux ref., flux current, Inverter output current/voltage, Motor Temp, DC link voltage¡¦ )

AO2 Analog output 2

AO3 Analog output 3

5G COMMON COMMON terminal for analog output

Open collector output OC1 Open collector output Selectable among the following 14 functions;
Zero speed detect, Speed detect (Bi-directional), Speed detect (Uni-directional), Speed reach, Speed deviation, Torque detect, On Torque limit, Motor overheat, Inverter overheat, on low voltage, Inverter running, Inverter regenerating, Inverter ready,Timer output




Digital output 1A Multi-function input 1 (A Contact)


2A Multi-function input 2 (A Contact)


30A Fault alarm A contact Outputs when fault occurs.
Deactivated in BX condition.

30B Fault alarm B contact

30C COMMON COMMON for 30A, 30B


Keypad features

2.4 Connection Diagram of inverter

2.5 Types of Fault
Over current
Over current 2
Ground Fault
Inverter Overload

Overload Trip
Inverter Overheat
Output Phase loss
Over Voltage
Low Voltage
Electronic Thermal
Input Phase loss
Self diagnostic multifunction
Parameter save error
Inve3rter hardware Fault
Communication Error
Key pad Error
Cooling fan Error
Instant cut off
External Fault A contact input
Brake contra Error
Over current Fault
Over Current 2
Ground fault current

Inverter has no power
SMPS Circuit Problem
Replace SMPS Circuit

No Power
Cooling Fan Fault
Circuit Servicing
Replace Cooling Fan
No Power
Power Card Fault
IGBT Fault
SMPS Card Fault
Damage Braking Resistor
Replace IGBT
Replace SMPS Card
Replace Braking Resistor(200 Ohm)

Key pad LED Direct flashing
Polar Capacitor Fault
Replace it, new polar capacitor solder there.

Output Error

Replace IR2133J Rectifier.
Key pad light (Run,Set,Rev,Fw) flashing at a time.
IGBT Fault
Replace IGBT
Low voltage fault
Replace Power circuit resistor

Does not show display.
SMPS Card fault
Replace capacitor of SMPS card

No Power
Power Card Fault
IGBT Fault
SMPS Card Fault
Damage Braking Resistor
Replace IGBT
Replace SMPS Card
Replace Braking Resistor (200 Ohm)

Fig-22: Inverter synchronization

Fig-23: Sub Power PCB of inverter

Fig-24: Main Power PCB

Fig-24: Main Power PCB

Fig-25: Control card of Inverter

Fig-:26 Burnt IGBT

Fig-:27 IGBT Test

Fig-:28: Rectifier


PLC (Programmable Logic Controller) and Inverter is a latest intelligent instrument that is used widely in different industrial plants to operate automatically with decreasing the plants breakdown times as well as its maintenance costs and increasing both of quality and quantity of productions. Considering of its high reliability and low cost most of the organizations are now trying to replace their old control system with new PLC control system. So as an Electrical Engineer sufficient knowledge about PLC and Inverter should know.

Accuracy: The closeness of an indication or reading of a measurement device to the actual value of the qu