PLC, DCS, RTU, SCADA and PAC Systems

PLC – Programmable Logic Controller

PLCProgrammable logic controllers are electronic devices used to control a process. It consists of CPU; Input and output devices, power supply, communication and redundancy units. PLCs are preprogrammed based on their application and put into operation. A PLC accepts inputs from the field, process the input based on the programming done and outputs the commands to the field equipment. It can also accept commands from the plant operators through SCADA and give commands to the field equipment. The features of PLCs vary from one manufacturer to the other but the basic architecture remains the same. (more…)

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What is meant by stalling of motor?

Stalling is a condition at which a motor stops rotating even when there is sufficient voltage at it’s terminals. This condition occurs when the torque required by the load is more than the maximum torque (Breakdown torque) that can be generated by the motor. At this condition, the motor drains the maximum current and the speed comes zero.

Induction motor Torque-Speed Characteristics
Induction motor Torque-Speed Characteristics

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Voltage division rule | Potential divider circuit

Voltage division rule

Voltage division rule is one of the basic rules of circuit analysis. It is applicable to all series circuits and combination circuits. Series circuit always acts as a Voltage divider. In a series circuit, the same current flows through each resistance. Hence the voltage drops across each resistor are proportional to their ohmic value.

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Series and Parallel circuits

Series and parallel connection of lamps
Series and parallel connection of lamps
Current flow in a circuit is determined by the impedance offered by the circuit components, which is in turn determined by the way circuit components are connected. Series connection and parallel connection are the two simplest ways of connecting a circuit.
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Ohm’s Law – Relationship between current and voltage

Ohm’s law is one of the basic principles of electricity. It relates the basic parameters of electricity, Current and voltage, to each other. Georg Ohm, after whom the law was named, conduct a few experiments on circuits containing different lengths of wires and found that the voltage applied and current are directly proportional. He derived a complex equation and published it along with his results in the book Die galvanische Kette, mathematisch bearbeitet in 1827.
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Contactor – Construction, Operation, Application and Selection

Contactor- Construction, Working Principle, Application

An electrical contactor is a switching device, widely used for the switching of motors, capacitors (for power factor correction) and lights. As the name indicates contactor are used to make or break contacts as like an ordinary on-off switch. The only difference is that the contactors have an electromagnet that holds the contacts when energized whereas switches do not have it.
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Difference between MPCB and MCCB

Motor Protection Circuit Breakers and Moulded Case Circuit Breaker and are devices used to open and close a circuit manually and interrupt the circuit automatically on the occurrence of faults. MPCBs and MCCBs are used to protect against overload and short circuits. Application of Motor Protection Circuit Breaker is entirely different from that of Moulded Case Circuit Breakers.

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