types of static relay
When this happens a voltage is induced in the output winding and the relay gets energised. Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. where M is time-multiple setting, I is multiple of tap current; Ip is the multiple of tap current at which pick-up occurs, n is characteristic index of relay, t is time of operation in seconds and K is design constant of the relay. Terms of Service 7. Disclaimer 8. The first static relays developed were the high speed differential relays and the distance relays. The choice of directional unit depends upon the type of comparator used. The first static relays developed were the high speed differential relays and the distance relays. Staticrelays Components of static relays Block diagram of static relays Types of static relays Prepared By Mr.K.Jawahar, M.E., Assistant Professor Department of EEE Static Relays Kongunadunadu College of Engineering and Technology Depar tment of EEE When the phase angle between V and I exceeds certain predetermined value, the directional relay operates with a condition that the current is above the pick-up value. If time delay is desired, a timing circuit is introduced before the level detector. 4.5 (a) and 4.5 (b) current of constant magnitude flows in the collector circuit only when the input ac quantities are simultaneously positive; a relay in the collector circuit will pick up when the overlap angle exceeds a certain value, i.e., when the mean dc level in the collector circuit exceeds the relay pick-up as a consequence of phase coincidence. Electronic Relays 2. each type of relay. Prohibited Content 3. By varying values of R and C the time can be varied without difficulties. [gravityform id="1" title="false" description="false" ajax="true"]. In an actual relay, Ithreshold can be adjusted. Content Filtration 6. Static AC Switches Normally Open Circuit The circuit shown in Figure AN1007.1 provides random (any-where in half-cycle), fast turn-on (<10 µs) of AC power loads and is ideal for applications with a high-duty cycle. The Hall crystal as phase comparator has gained popularity only in Russia. Static Instantaneous and Definite Time Overcurrent Relays: The block diagram of an instantaneous overcurrent relay is shown in Fig. Both types of relay control electrical circuits through a switch that is open or closed depending upon an electrical input. Plagiarism Prevention 5. STATIC RELAY NAME- ROHIT KUMAR MARNDI REGD NO- F15152002039 BRANCH- ELECTRICAL ENGINEERING YEAR:- 2015-18 GOVT. When the input to measuring unit is less than the threshold value, the output of the level detector is zero. Gravitational force can affect the relay. The overcurrent relays, even though simplest of all types of electromechanical relays, are the most difficult static relays. Inverse-time relays are used where the source impedance is much smaller than the line impedance. The components used were electronic valves for measuring unit. The output of phase comparator is fed to the level detector. Compact in size – The size of a single three-phase overcurrent relay may be about one-fourth of three electromagnetic relays. 4.7 where two input signals are the sinusoidal ac currents I1 and I2. These relays could not meet practical requirements and hence never reached the commercial stages. The output of this summation CT is fed to an auxiliary CT, whose output is rectified, smoothened and supplied to the measuring unit (level detector). Smoothening circuit and filters are introduced in the output of the bridge rectifier. However, it takes up more room and is slower than an SSR. This effect depends upon the ratio of depth to width and increases with the increase in this ratio. Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. They are more complicated in static form as compared to their electromagnetic counterparts. A single coil which permits use … Static relays are contrasted with electromechanical relays, which use moving parts to create a switching action. CPU 3. Static relays are classified according to the type of the measuring unit or comparator as follows: 1. Directional relay senses direction of power flow by means of phase angle between V and I. This is because the induction disc characteristics of the overcurrent relays (inverse characteristics) are not amenable to simple mathematical analysis. The characteristic becomes a straight line parallel to current axis for n = 0. When a conductor is kept perpendicular to the magnetic field and a direct current is passed through it, it results in an electric field perpendicular to the directions of both the magnetic field and current with a magnitude proportional to the product of the magnetic field strength and current. I1 = I1max sin ωt and I2 = I2max sin (ωt – α) …(4.2), Flux through crystals I and II will be ɸ1 α I1 and ɸ2 α I2, and current through the crystals will be I’1 [α (dI2/dt)] and I2 [α (dI1/dt)] …(4.3), Two crystals I and II are connected in such a way that their output voltages are in opposition. Low CT burden – The VA consumption of static overcurrent relays is quite low (7 mVA to 100 mVA) as compared with that of electromagnetic relays (1VA to 3VA) so that smaller CTs are required. Gauss Effect Relays. Static relay with output contacts – A static relay having a contact in one or more of its output circuit (s). History of Relay. Time delay overcurrent relays are used in overcurrent protection of utility equipment, distribution circuits, protection of transformers, generators, motors etc. 2. Less maintenance, long life and not affected by shock and vibration. With n = 7 or 8, the characteristic becomes extremely inverse. Two basic arrangements of relays based on transistor comparators are shown in Fig. Static Relay Presentation 1. Because of the high cost of Hall element, low output and large temperature error, this comparator is normally not used. Time delay relays 2. The secondaries of the line CTs are connected to a summation circuit (not shown in the figure). Types of Relay Elements: The Important Types of Relay Elements or also called Electromagnetic Types are 1.Induction Disc Relay The shaded pole type gives the most effective form of an electromagnet since it has the following: Higher torque/VA. This interaction costs printed-circuit board real estate, typically 0.2 inches (5 mm) on all sides of an EMR, a hidden cost of using an EMR solution. The double frequency term can be eliminated by cross-connecting two Hall generators, as illustrated in Fig. Digital input/Communication module Input Module The Power system operates with analog parameters. The transductor relays are mechanically very simple and are quite reliable. The transistor circuits cannot only perform the essential functions of a relay (such as comparison of inputs, summation and integrating them) but they also provide necessary flexibility to suit the various relay requirements. Therefore solid state relays are also called as static relays. The operating winding is wound in such a way that the ampere-tums so produced oppose the restraining ampere-turns in one limb and strengthen them in the other. In some metals, this effect is noticeable at room temperature, as in case of bismuth. However, static overcurrent relays offer several advantages over the electromagnetic form: 1. Content Filtration 6. Copyright 10. Such a characteristic is known as definite time characteristic of overcurrent relay. Because reverse ARP is enabled by default, no additional commands are required. In this article, the different types of relays like overload protection relay, solid state relay, solid state contactor relay, Buchholz relay, Mercury Wetted relay and … The effect of this is to drive both the limbs on which the operating winding is wound into saturation. The component of the static relay is shown in the figure below. A solid state relay is composed of both static and electromechanical units in which the response is accomplished by the static units. However, static overcurrent relays offer several advantages over the electromagnetic form: The control windings are energized with dc and the operating windings with ac. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay. Functions: 1 relay can perform various functions. On the other hand the windings of the different groups are not magnetically linked. Content Guidelines 2. Disclaimer 8. Plagiarism Prevention 5. As there is no moving part, operating time of the order of 0.02 s (1 cycle) can be achieved. Thus directional relay is a double actuating quantity relay with one input as current I from CT and the other input V from PT. The RSR-72 type relay for re-start and reacceleration is deigned to perform the automatic motor restarting, after control and protection device opening, as a consequence of a momentary line voltage interruption or drop-out. Huge Collection of Essays, Research Papers and Articles on Business Management shared by visitors and users like you. On occurrence of ground fault, the zero sequence current will flow through the relay coil and relay will operate if the relay current exceeds the threshold value. The relay which consists static and electromagnetic relay is also called static relay because the static units obtain the response and the electromagnetic relay is only used for switching operation. Hence less panel space is required in case of static overcurrent relays. Extremely inverse overcurrent relays are used for the fuse coordination and thermal protection of transformers and induction motors. The basic R-C circuit can also be arranged in several series-parallel combinations to have different values of TC. For an overcurrent relay-, For Iinput > Ithreshold ; Ioutput = Present. Cisco routers support all network layer protocols using Frame Relay, such as IPv4, IPv6, IPX and AppleTalk. The output of the level detector is amplified and in case a timer is necessary, the output is applied to the output device through the timer. According to the principle of operation and construction, the relay may be classified such as the electromagnetic attraction type, electromagnetic induction type, electrodynamic type, moving coil type, electro-thermal type, physics electric type, and static relays. 1. The technique of overcurrent relaying is still widely used as a means of fault detection on distribution system and on transmission lines supplied from one end. The directional overcurrent relay can be made either instantaneous or time-lag type. Due to smoothening and rectifying a signal, a delay is introduced because of the time constant of the smoothening circuit and hence the relays are slow in operation and, therefore, are discarded for protection applications. Nonlinear resistors are used to have other time characteristics. Types of solid state relays include reed relay coupled SSR, … In addition to these the other types of static relays are: Hall effect relays; Inverse time overcurrent relay; Directional static overcurrent relay; Static differential relay; … This phenomenon is called the Hall Effect. That is why a heavy duty telephone type relay is employed with large setting. UNIT II - RELAY CIRCUIT Static relay circuit (using analog and digital ic’s) for over current: The Solid State Relay (Static Relay): History of Relay: The static relay are next generation relays .The Solid Static relays was first introduced in 1960’s. Copyright 10. This relay consists of two rectifier bridges and a moving coil or polarized moving iron relay. Electronic Relays: These were the first to be developed in the series of static relays.