Disadvantage of Definite Time Line Protection. Relays have different functions and use currents, voltages, or their combination (impedance) to identify a fault. Different Types of Relays. Principles of Differential Relaying Voltage Balance I1 I 2 Protected Object R i2 i1 R. Principles of Differential Relaying Voltage Balance Normal conditions, I1= I2 as before. The disadvantages of a conventional electromechanical relay are overcome by using microcontroller for realizing the operation of the relays. • Relay operation can be affected due to ageing of the components and dust, pollution resulting in spurious trips. Fig. Advantages of Solid-State Relays Over Electro-Mechanical Relays. 1) Type test 2) Production test 3) Commissioning test Relay testing Function testing 4) Periodic maintenance test The first two tests are usually completed by the manufacturer and the last two by a relay tester. Protective relays continuously monitor these parameters: voltage, current, and power; and if these parameters violate set limits they generate an alarm or isolate that particular circuit. So during any fault nearer to the source will take much time to be isolated. What happens when polarity is wrong? Meter spins backwards indicating power generation instead of power usage – results in decreased revenue Relays detect power flowing in the wrong direction – results in power outages Polarity. Possible additional circuits: Earth fault detection Automatic starting protection … In the lifecycle of a relay, a relay will go through 4 different phases of testing. Inverse Time Overcurrent Relays (IDMT Relay) In this type of relays, operating time is inversely changed with current. Unlike fuses and switching devices, relays require CT and PT input to detect the fault, and a circuit breaker in order to isolate it. Relays detect and isolate faults indirectly. The disadvantage here is that a fault in the vicinity of the feed point, where the tripping time t > is longest, results in the highest current. If you want to protect your house or workplace from short circuits or any abnormal faults, use / buy protective relays. Microcontroller based relays perform very well and their cost is relatively low. DISADVANTAGES:- • The directional feature is absent in electromagnetic relays. In distance relays, the operation tit dependent on the ratio of the voltage and current, which is expressed in terms of an impedance. Differential Relay Scheme What is the advantages and disadvantages of a differential relay. A relay is an electrically operated switch.It consists of a set of input terminals for a single or multiple control signals, and a set of operating contact terminals. The relay contacts and coil terminals are designed as plug-in blades. Generates noise due to its mechanical parts; Limited lifetime ; It is slow because of the mechanical parts when compared to semiconductor-based relays; Applications: Here are some applications of electromechanical relays. We recently had a large industrial client install Square-D meters (at a high cost) to keep the protective relays off of the network even though the data is the same. Consequently, additional protective measures are needed here. Used for the protection of various AC and DC equipment; Motor control and automotive applications; To control large power … The operation of the relays is dependent on the magnitude of the current or voltage of the circuit to be protected. The client's justification was "meters can not be … Protection.IC2/2 of comparator IC used for under voltage protection. Buy a good quality protective relay online, as it saves your lengthy time and effort of offline shopping. 4. 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