A relay should not be directly connected to a microcontroller, it needs a driving circuit. Over current relay working principle types electrical4u. How to drive a relay using microcontrollers vishnus blogs. A relay can be easily interfaced with microcontroller using a transistor as shown below.
Relay is used in all the home automation projects to control the ac home appliances circuit diagram. The protective relay is most often relay coupled with circuit breaker such. To control our high voltage device like home appliance by pic microcontroller, we have to have clear idea on interfacing relay with pic microcontroller. Relay isolates low power circuits from high power circuits. Jun 01, 2010 im new to this forum and to the world of pic microcontrollers programming. The numerical directional overcurrent relay is a powerutility grade, numerical protective relay siemens siprotec 5 series mounted in a tabletop enclosure. See a simple circuit for controlling a single relay with pic 16f628. Microcontrollerbased overcurrent protective relay all. Overcurrent protection free download as powerpoint presentation. Microprocessorbased protective relays applications in. Should the appliance or circuit be damaged or overloaded, it will begin to draw current in excess of.
This is actually called electromagnetic relay but in short we call it a relay. Most of all protection relay only act as the brain of the protection and actual switching work are done by the circuit breakers and isolators. So by using relay switch we easily turn on or off any high voltage device by microcontroller. In this study, a digital protection and wyedelta starting relay based on pic 16f877 microcontroller has been implemented for threephase. Appropriate relay testing provides a first defense against relay maloperations and hence improves power grid stability and prevents catastrophic bulk power system failures. Direct incircuit programming for easy program updates iv. The transistor is driven into saturation turned on when a logic 1 is written on the port pin thus turning on the relay. Overcurrent protection of transformer by incorporating. Microcontroller do not have considerable amount of current to operate relay. To interface relay with microcontroller we need a driver circuit to drive the power to relay. Over current protection relay using pic micro controller zoolnasri, abu harun 2007 over current protection relay using pic micro controller.
But it can also be used for other applications,like small stepper motor drive or a high output power inverter for a. In 1993, a new approach was introduced using the ratio of negativesequence voltage. Pdf microcontroller based numerical relay for induction motor. Electric power systems research 38 1996 11 i7 microcontroller based overcurrent relay and directional overcurrent relay with ground fault protection zhijun gan, s. A relay is somewhat similar to a switch many students in engineering in particular electrical have a wrong notion that relay means protection relay. Im new to this forum and to the world of pic microcontrollers programming. Overcurrent protection of transformer by incorporating idmt function with the help of arduino uno microcontroller ankit agarwal department of electrical engineering iftm university,moradabad, india abstract power transformer is an important and vital part of the electrical power system, there protection and continuous. What will be connected to the relay output and how much current is required for the relay output. The setup is designed in a control box and the arrangement is made so as to experiment. Coordination of overcurrent relay for radial and parallel. The pic can determine the amount of time the switch is held, and then either change devices or continue to operate the current device. Microcontroller boardscontrol the relay operations by using pic16f18f slicker board.
Raig is available in several versions, with and without timelag relay and with different duty on trip outputs. I have a project im working on which is to design a microcontroller based overcurrent protective relay. The input to the tranformer is gs iven from the supply of 230 volt, 50 hz supply. The relay can perform the protection functions listed below. Keywords adc, differential relay, embedded c programming, i to v converter, pic microcontroller. Fundamentals and improvements for directional relays. When the microcontroller s output is on, the relay turns on too. Aug 17, 2017 figure 1 shows the basic relay driver circuit. The switch relay circuit is based on a pic microcontroller microchip, inc. It is activated by energizing a coil wounded on a soft iron core. Ef relay for over current and earth fault protection. To design and develop an over current protection relay using microcontroller which can operate on the permissible conditions by setting the over current value.
Synchrocheck relay ac under voltage relay power directional relay under current mor under power relay field control loss of field relay dc over voltage relay reverse phase or phase balance current relay phasesequence or singlephasing voltage relay machine or transformer thermal irelay instantaneous over current or rateofrise relay. Feb 05, 2014 to control our high voltage device like home appliance by pic microcontroller, we have to have clear idea on interfacing relay with pic microcontroller. How to control a relay from pic microcontroller circuit. Im programming using c and im using hitech compiler with mplab. Im using pic16f877a chip along with ql200 development board. In this work, new technologies that allow designing an enhanced relay testing system that can be used for improving the performance of protective relay have been used. Other types of relays also used know as solid state relay in which dc voltage used as input. Jul 22, 2017 in this video, well learn how to interface relay with microcontroller. For phase to phase faults the relays in only the affected phases operate. Please note that when there is no load, the relay command fully works, without resetting the microcontroller. To design and fabricate over current protection relay using pic micro controller. How to control a relay from pic microcontroller circuit diagram simply you can control a relay through pic microcontroller. Working principle of over current relayin an over current relay, there would be essentially a. Protection relay play an important role in this system to cause the circuit breaker to trip and it can be implemented at various stages and various types of protection devices.
Interfacing relay with pic microcontroller youtube. When the pin rb7 of the pic microcontroller goes high, the transistor bc547 turns on and current flows through the relay. The type ifcv51ad relay is a singlephase, extended range, very inverse time overcurrent relay with voltage restraint. The microcontroller is programmed in such a way that it will perform its action whenever there is abnormal conditions such as overvoltage or overcurrent situations. This motor overload circuit does not simply disallow overloading since it is permissible to overdrive a system but only if it is done for a short time typically dependent on heat buildup. Field of the design the design relates to overload detection circuits for the protection of electrical motors and other electrical equipment. An earth fault relay has been implemented in our project by using with different relay characteristics. There is only one current operated element in the relay, no voltage coil etc. The electromechanical relay scheme uses threephase. Under normal operating conditions and three phase fault conditions the current in the 3phase are equal and symmetrically displaced by 120.
These devices typically consist of a manual circuit breaker or contactor and a current sensing relay which interlocks with it. Sep 27, 2016 power processing is one of the most important aspects on electronic design. Overcurrent protection read 4564 times previous topic next topic. Over current protection relay using pic micro controller. Now i will explain you the working of this circuit. Jun 12, 2018 in this project we will interface a relay with pic microcontroller pic16f877a. This project, an overcurrent detection circuit from 1983, continuously detects and processes for an over current state while driving a motor, and at the same time it allows short overloads to pass through.
Mar 22, 2015 the switch relay circuit is based on a pic microcontroller microchip, inc. But it can also be used for other applications,like small stepper motor drive or a high output power inverter for a signal voltage input of 5 volts. When the relay needs to be shut down, microcontrollers output is off. As a programming language, basic is since long time ago. The protection scheme also includes a singleshot recloser for automatic line restoration after a fault has been cleared. The secondary of the transformer is connected to the ammeter 010 amps to. The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time.
When microcontroller makes the output line high binary 1, the transistor is switched on. For detailed working of relay please visit this page. An overcurrent relay is an electrical protection device designed to cut off the power supply to a circuit, appliance, or machine in the event of an overload or failure. Interfacing a relay with pic microcontroller mikroc. Push button as input and led as output with pic microcontroller. In the end, we have presented fully functional relay operated light bulb using mobile app. See the block diagram below to how we turn on or off a 230 volt ac bulb by micro controller. Phase angle measuring or out ofstep protection relay reclosing relay dc under voltage relay frequency relay lockout relay differential protective relay. In this project, pic microcontroller will be used tocontrol and operate the tripping coil in circuit breaker. To design and fabricate over current protection relay using pic micro. Pdf this paper presents a design of nondirectional overcurrent relay microcontrollerbased. Current flows from the 12v input to the relay and then to the ground via the transistors collector pin. How much current is required to energize the relay and what is the voltage rating. Micro51 microprocessorbased overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems.
A relay is an electromagnetic switch which is used to switch high voltagecurrent using low power circuits. May, 2020 an overcurrent relay is an electrical protection device designed to cut off the power supply to a circuit, appliance, or machine in the event of an overload or failure. Microprocessorbased time overcurrent relay micro51 micro51 microprocessorbased overcurrent relays are used for phase and ground overcurrent protection in utility, industrial and commercial electrical power systems. Microcontroller based overcurrent relay and directional. As you can see an npn transistor bc547 is being used to control the relay. Microprocessorbased relay evolution 1993 when the source behind the relay is strong, the voltage measured at the relay location for a remote fault can be too small to overcome the minimum torque requirements of a torqueproduct directional element. Liew department of electrical engineering, ivational unmersrty of singapore, 10 kent ridge cresccn, singapore 119260. This current switches on the relay which in turn switches on the ac load the bulb the diode d1 1n4007 is used as a flyback diode. When the coil is energized, the switch closes, connecting the two contacts together. In an over current relay, there would be essentially a current coil. In an over current relay or oc relay the actuating quantity is only current. To design and fabricate over current protection relay using pic micro controller which can operate on the permissible conditions by setting the. Hellebuyck, programming pic microcontrollers using. Directional phase overcurrent 67 protection directional ground overcurrent 67n protection directional power 32 protection instantaneous phase overcurrent.
An earth fault relay has been implemented in our project by using with different relay characteristics further the multifunctional properties can be extended. To test unwanted conditions over current and when such conditions arise to isolate the fault condition in the shortest possible time. The micro51 operates from conventional 5a or 1a secondary current transformers. Microcontroller based protective relay testing system. A 3 design the overcurrent protections raig are built up based upon the overcurrent relay rxig 2. Description of the prior art one prior overcurrent detection device is disclosed in grzebielski, u. Overcurrent relay and protection 1mrk509010ben revision.
When rb5 port of pic become high the relay will operate. When the pin rb7 of the pic microcontroller goes high, the transistor bc547 turns on and current. Hence, we extended the same for pentium processor also. Feeder can be protected from the over current condition. Relay is a mechanical device to control high voltage, high current appliances on or off from lower voltage levels. Oct 21, 2014 when microcontroller makes the output line high binary 1, the transistor is switched on. When the relay needs to be shut down, microcontroller s output is off.
The setup for this research activity is carried out in electrical lab of kathmandu university. Hello folks, i am designing a circuit that will supply 12v to a device that the user will connect the voltage will be switched by a mosfet which will be controlled by a microcontroller based on some input. In this project, pic microcontroller will be used to control and operate the tripping coil in circuit breaker. Currentonly directional overcurrent relay abhisek ukil, senior member, ieee, bernhard deck, vishal h shah abstract overcurrent relays are widely used f or protection of. Ground faults are detected using a directional ground overcurrent relay which includes a timeovercurrent element and an instantaneous overcurrent element.
How to interface relay with pic16f877a pic development board. Overcurrent protection relay electrical substation scribd. Design and implementation of oc relay using microprocessor. Feb 14, 2011 uln 2003 is generally used as a relay driver ic. The time overcurrent unit is similar to the ifc5ia relay except that a voltage restraint umagnet and coil has been added that produces a restraint torque that opposes the operating coil. In this project an overvoltage and overcurrent relay which is made using a microcontroller.
Sep 01, 2018 in an over current relay or oc relay the actuating quantity is only current. Uln2803 is used as a driver for port io lines, drivers output connected to relay modules. In this video, well learn how to interface relay with microcontroller. Figure 4 shows the circuit diagram of the over current protection of 1 kva transformer with pic microcontroller using numerical relay. Before starting to make the project for a power supply we need to analyze some aspects. Pdf design of prototype non directional overcurrent relay micro. A proposed scheme of overcurrent relays dealing with programming of the singleboard microcomputer tk85, built by nec around intels 8bit 8085 microprocessor, is described. Microcontroller interfacing to relays using uln2003 relay. It protects the equipment of the power system from the fault current. Relay interfacing with pic microcontroller pic16f877a. Microcontroller based lowset oc is highset oc ihs lowset ef os highset ef is oc is 50200% step 10% or ef is 1040% step 2% or. Which kind of radioelectromagnetic interference is the device going to face.
When the microcontrollers output is on, the relay turns on too. Relay provides isolation between two voltage levels and it is generally use to control ac appliances. When normal current flows through this coil, the magnetic effect generated by the. Nov 24, 20 in this project an overvoltage and overcurrent relay which is made using a microcontroller. The power is unique for a typical system because it gives the system life.
Depending on the time of operation the overcurrent relay is categorized into following types. Transistor is wired as a switch which carries the current required for operation of the relay. Over current relay, microcomputer module, pickup current. Stepper motor circuit using pic microcontroller datasheet. To design and fabricate over current protection relay using pic micro controller which can operate on the permissible conditions by setting the over current value. For example, imagine the user uses this device to switch a bulb onoff based on some input to the microcontroller. Circuit we are using in this tutorial is shown below. Before you connect a relay to a microcontroller, you need to first make a few decisions. The proposed overcurrent relay can be employed to protect feeders of distribution. Relay interface to microcontroller by uln 2003 youtube.