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What is PLC (Programmable Logic Controller), PLC SCADA & its types?

PLC (Programmable Logic Controller):-

PLC controls the process .It is a Hardware device. Micro-Processor and Memory inbuilt in plc. It’s work on 24v dc. There are so many company which made it. PLC makes easy of process by automation.

SCADA (Supervisory Control & Data Acquisition):-

Really, SCADA is a graphics representation of process. It is a Software.
It supervised the entire process and save the data. Save the data means which equipments are open and close, when were started, at which time what happened in process.


DCS (Distributed Control System):-

It is a complete system of PLC & SCADA. It use in big plant like chemical fertilizer, oil & gas, power plant. It has multiple brains. When I/O’s more than 1 000 then will be better to use DCS.

Automation :-

It is basically the delegation of human control functions to technical equipment for increasing Efficiency, Proficiency, Accuracy, Production, saving cost & safety of men & machines. Automation is used in right from Agriculture to Space..

Types of Automation

 Industrial Automation :- Manu-factoring & processing Units-Plants, Power generation.
 Building Automation :- BMS, HVAC, Security, Power back-up, WTP.
 Office Automation :- LAN, MAN, WAN..
 Science Automation:- DRDO, ISRO, NTPC, R & D, ORDINANCE, Etc.
 Sub Station Automation :- Time & Division(T&D) .
 Home Automation :- Depends on us..
All are Non-IT sectors.
Only testing automation used in IT sector.

 Plant —-FIELD INSTRUMENTS—-PLC OR DCS—-SCADA OR HMI…….

Sensor is a device which sense the object without physical touch and convert into non electrical signal to electrical signal..
Transducer is a device which convert non electrical signal into electrical signal & vice versa.It is a physical device.
Sensor is a part of Transducer but Transducer is not a part of Sensor. Both are use in AUTOMATION for controlling. Sensor & Transducer both are used for controlling in Automation.

Inputs & Outputs

There are some outputs given below 1. INDICATORS ( RED YELLOW BLUE GREEN ) 2. VFD (VARIABLE FREQUENCY DEVICE) 3. BUZZER 4. SOLENOID VALVES 5. RELAY & RELAY CONTACTS 6. CONTACTOR 7. TOWER LAMP

Now there are some inputs given below.
1. PUSH BUTTONS (NO-NC)
2. SELECTOR SWITCH (TWO WAY & THREE WAY)
3. TOGGALE SWITCH
4. PROXIMITY SENSOR
5. LIMIT SWITCH
6. PHOTO SENSOR (ALWAYS USE IN CONVAYOR)
7. REED SWITCH
8. TEMPERATURE SENSOR
9. FLOW METER

DEVICES ARE USE IN AUTOMATION :-

MCB(MINIATURE CIRCUIT BREAKER):- Manually operated electrical switch
It is tripped on short circuit & overload and protect the circuit.
There are three types of trips :- overload trip, short circuit trip, manually trip. We are use MCB at the place of FUSE.MCB is use in single current rating
MP CB(MOTOR PROTECTION CIRCUIT BREAKER):-
It is a combination of MCB & OLR. We can set the current rating.
Earth leakage protective. It’s switching time is too short in compare to other device. It can save devices by line to line fault, line to ground fault, overload protection Phase unbalance
CONTACTOR:
Three phase switching device automatic controlling switching device used in power circuit. It`s work on three phase as desire of us. It work on only dc power supply.
RELAY:
It is also a switching device which used in control circuit. It is used in only single phase. It is work on both ac & dc power supply .
OLR (OVERLOAD RELAY):
It is also use for protection. We can set the value of current in OLR. There are only two types of protection we can use in OLR.
Thermal protection & Phase failure protection. There is no short circuit protection it can only in MCB.
CT (CURRENT TRANSFARMER):
When we need the measure the Current in Industrial Plant . We can use it easily . In industrial plant we measure heavy current. We use it in single-phase-line and measure the current.
PT (POTENTIAL TRANSFARMER):
When we need the measure the Voltage in Industrial Plant . We can use it easily . In industrial plant we measure heavy Voltage. We use it in phase – neutral and measure the Voltage.
In Series Voltage high & Current low and In Parallel Voltage is low & Current is high. So we can measure the Current in CT & Voltage in PT.
VFD (VARIABL FREQUENCY DEVICE):
It is most important device in industries. It is use for controlling the speed of Induction Motor. We can control the speed of starting & stopping. VFD is a device which control & protect the Motor. It is a convertor.
It converts AC to DC & then DC to AC.
(I/P)AC—- Rectifier—- Filter—- Control—- Inverter—- AC(O/P). Speed is directly proportional to Frequency.

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