The comparison between analytical calculation results and experimental results shows the accuracy of the built model. The static relay is more costly as compared to the electromagnetic relay. NUMERICAL RELAY In 1985, the first protection devices based on microprocessors were employed. The working principle of the mechanical relay is the principle of electromagnetic induction. I have noticed that still in many plants, people don't know how to download settings, Fault Record and configurations from Numerical Relay. Being based on entirely different switching principles, t he direct comparison between semiconductor relays and electromechanical relays turns out to be delicate. Pickering Electronics, an established reed relay manufacturer, was founded in 1968, and even then some were saying that these electromechanical devices would have a limited lifetime. Semiconductor switching devices. NO keeps the circuit open and NC keeps the circuit closed. COST COMPARISON OF NUMERICAL RELAY WITH ELECTROMAGNETIC AND STATIC RELAY 39 ATMOSPHERIC ENVIRONMENT A relay is generally suitable for temperature as per IEC 255-6 for storage at –25°C to +70°C, and for operation at –25°C to +55°C. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. Difference between NO and NC. Time delay is type of electromechanical relay which are used to provide a delay in the start-up, shut-down or controlling processes. A failure of a numerical relay may cause many more functions to be lost compared to applications where different functions are implemented by separate hardware items. The relay has less overloading capacity. And the same relay can be used for analysing and monitoring multiple faults such as over current, over fluxing, different current and more. Such relays are also termed as microprocessor type protective relays. Difference between earth leakage relay and earth fault relay. Instead, the market for high-quality reed relays has increased into areas that were inconceivable in those days. It is very easy to provide electrical isolation between the coil that creates the magnetic field and the switch contacts. A calibrated adjustment . Comparison of reliability and availability between the two methods is complex as inter-dependency of elements of an application provided by separate relay elements needs to be taken into account. It uses a flag system for the indication purpose whether the relay has been activated or not. Electromechanical, electronic, digital, numerical, and today smart relays represent a trend in the field of power system protection and in a special case, protection schemes of transmission lines. These relays suffer from the effects of age. As time passes, the springs and the linkages inside the relay grow weak. If we clear the concept for these relays first then understanding the Numerical Relay settings becomes easy. Conventional electromechanical and static relays are hard wired relays. Few of the differences between conventional (electromechanical) and solid state (digital / numerical) relays can be highlighted as below: An electromagnetic relay is a switch that is turned on and off by a magnetic field. The induction disc type relay is based on the same principle as that of an ammeter or a volt meter, or a wattmeter or a watt hour mater. Relay are electro-mechanical switches that have coil and two types of contacts that is NO & NC. An electromagnetic relay can be classified according to the nature of the intermediate signal between the primary side and the switching element. Its wiring is fixed, and the setting is manually performed. Advantages of Numerical relays 1. Compact Size. The relays control the electric circuit by opening or closing the contacts of that circuit. PSM and TMS settings that is Plug Setting Multiplier and Time Multiplier Setting are the settings of a relay used to specify its tripping limits. Also, it requires continuous power supply. If the voltage is applied below the operating voltage, the Relay is de-energized (Switch is in OFF state). Figure 2 shows cost comparison of numerical relay with electromechanical and static relay [1]. ... INDEX TERMS Electromechanical relay, … Buchholz Relay – Working Principle, Construction and Operation In this condition, the relay is on when the control voltage exceeds the operating voltage. In utility and industrial electric power transmission and distribution systems, a numerical relay is a computer-based system with software-based protection algorithms for the detection of electrical faults. The electromechanical and static relays are hard wired Therefore solid state relays are also called as static relays. A relay is electro mechanical switch which is controlled electrically. Numerical relays are all microprocessor based, but there are relays that take the advantage of microprocessor technology and are not fully numerical. Contacts: A Solid-state relay consists of the following sections: 1. numerical relays relay technology electromechanical relays : mechanical forces causes operation of relay contact in response to a signal. Optocoupler 3. One of the major advantages of numerical relays is that it can store pre-fault as well as post-fault data so that it can be used further. There are several ways of doing this, but the common theme between them all is the lack of moving parts, thus making them solid-state. Hence, the Potential and the Current Transformers should have a higher capacity. Types of Relays The relay may be defined as an electrical device interposed between the main circuit and the circuit breaker in such a manner that any abnormality in the circuit acts on the relay, which in turn if the fault is dangerous then it causes the circuit breaker to isolate and so to remove the faulty element. An equivalent terminology chart is used as an aid in the comparison of EMRs and SSRs. While Numerical Relay is in Compact Size and use Indication on LCD for Relay activation. To understand simply it is like a brain in our human body, when the brain gives the sense the body parts are operate to do any work. An electromechanical relay consists of three terminals namely common (COM), normally closed (NC) and normally opened (NO) contacts. Now, Bulb 2 will not glow and Bulb 1 is in ON state. Electromechanical Relays. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. All about the electromechanical relay The electromechanical relay uses physical and moving components to attach with its output. In static relays, the measurement is performed by electronic/magnetic/optical or other components without mechanical motion . Time Delay Relays. Thus, precaution should be taken for avoiding the damages through voltage spikes. History of Relay: The static relay are next generation relays .The Solid Static relays was first introduced in 1960’s. Numerical relays are mostly preferred because of their versatile characteristics. Compact Size: Electromechanical Relay makes use of mechanical comparison devices, which cause the main reason for the bulky size of relays. Many of you have Numerical Relays in your plant for protecting different Electrical equipment's like Generator, Transformers, Transmission lines and Motors.But, many times we don’t use Numerical Relay to its full or atleast 80% of its capability. 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