Tronical World

What is DOL Starter : Direct On Line Starter is used to start three phase motors below 5 H.P. rating in industries. As the name suggests it connects the motor directly to the line (power supply). Main components of DOL are: -                       #  Push buttons -           #  MCB -           #  Contactor Two push buttons are used, one NO for start operation and one NC for stop operation. MCB is used as a protection device so as in case of any short circuit or over current, it trips and breaks the supply. Major used in a DOL starter is Contactor. Contactor works in similar way as relay works. When coil of contactor is energized its power contacts are closed so as to start the connected motor. Control wiring of DOL starter is shown below: DOL Starter Now if we are making DOL using a PLC, then we can use any button (NO or NC) for any o...

The schematic symbology for switches vary according to the switch's purpose and actuation. A normally-open switch contact is drawn in such a way as to signify an open connection, ready to close when actuated. Conversely, a normally-closed switch is drawn as a closed connection which will be opened when actuated. Any kind of switch contact can be designed so that the contacts "close" (establish continuity) when actuated, or "open" (interrupt continuity) when actuated. For switches that have a spring-return mechanism in them, the direction that the spring returns it to with no applied force is called the normal position. Therefore, contacts that are open in this position are called normally open and contacts that are closed in this position are called normally closed . There is a concept need to remember while using inputs in PLC programming. We can wire both NO or NC inputs to a PLC. These inputs could be pushbuttons, toggle switches, limit switches...

PLC Programming : There many languages to program a PLC like ST, FBD, IL etc. but most commonly used one is “LADDER” Language. As the name suggests, program in this language is built like ladder. Two vertical lines called rails and in between various horizontal lines called rungs. Symbols:         Normally Close (Examine if Open) Normally Open (Examine if Close) Coil These are three basic symbols used in LADDER programming.  NORMALLY OPEN:-   A  n ormally open contact corresponds to the use of the direct state of the input. If the input is supplied, the contact is said to be conducting. NORMALLY CLOSED:- A normally closed Contact corresponds to the use of the reverse state (logical complement of the direct state) of the input. If the input is supplied, the contact is said to be non-conducting. COIL:- Outputs correspond to the smart relay output relay coils.  Programming Examples:  1. Make...

PLC vs. Microcontroller: PLC and Microcontroller both are used in automation industry. But there is a major difference between area of their applications. So to know that first of all we have to understand the difference between the two. As we know Microcontroller is a chip (IC), could be 20 pin, 40 pin or else. Pins of a uC are very sensitive and requires high care while handling. These pins can easily break. On the other hand manufacturers of PLC make the outer body of PLC with very robust material. It can withstand jerks, temperature hikes etc. uC is a device that mostly works on 5VDC. Whereas PLC can work on different voltage ranges like 12VDC, 24VDC, 48VDC, 110-240VAC etc. uC has a limited number of Input/Outputs and it can’t be extended with extensions. Whereas PLC has a wide range of I/Os available and further it can be extended with compatible extension modules. uC requires additional circuitry to transfer any programs in to it but PLC requires just a programming...