relay characteristics curves

Each relay has two mechanical parts inside. We'll assume you're ok with this, but you can opt-out if you wish. This type of relay is widely used in applications where the state of the relay needs to be kept as is, even after a power failure or a restart. Working Principle of Over Current Relay. •Determine the characteristics, ratings, and settings of overcurrent protective devices •Ensure that the minimium, un-faulted load is ... Time-Current Curves Protective Relays 50 – Instantaneous Overcurrent Relay 51 – AC Time Overcurrent Relay 67 – AC Directional Overcurrent Relay . This relay changes state as long as the electromagnet is actuated, and goes back into relax state when the electromagnet is not actuated any more. On the next pushbutton press, the lights are turned off. The current/time-tripping characteristics of IDMT protection relays may need to be changed according to the functioning time needed and the characteristics of other relay protection elements used in the electrical network0.10 For these needs, IEC 60255 determined … Very important characteristic to take into account when designing the driver of the relay. The magnetic power of the electromagnets is not equal, thus the relay will cut the power supply and our friend will be saved. When the contact is still, then no current flows through it (because it is an OPEN circuit). Instead, they remain armed all the time. An DPST? Time vs. PSM Curve of Relay. Look the following image: Now you can see who is pulling the COMMON terminal UP all the time. Figure 1 shows a TCC plot of a fuse and an overcurrent relay. Two electromagnets are placed one opposite the other. In an over current relay or o/c relay the actuating quantity is only current.There is only one current operated element in the relay, no voltage coil etc. Because the highest FR values (ie, prices) ... delivery de vice and an electrom echanical relay th at provided. The number of contacts:…Just the number of contacts. For two contact pairs, it would be DP as for Double Pole. Coil The general code form is this: The ‘P’ stands for “POLES”. A permanent magnet is attached to the wheel of the bicycle, while the reed relay is fixed on the “fork” of the bike. The above are IEEE-standard curves; others are available, depending upon the relay make and model. This value should indicate also if the current is AC or DC. The reed relay’s armature is actuated from any other external magnetic field. This magnetism can overcome the force of the spring and can pull the contact towards it, thus it changes it’s position! The relay time characteristics differ by the rate at which the time of operation of the relay decreases as the current increases. The equation describing the Extremely Inverse Relay is I2t = K where I is operating current and t is time of operation of the Relay. They does not actually have an electromagnetic coil. The third and last category is the contacts of the relays. To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser. A coil is placed right under the contact. Nowadays, microgrids play a significant role in the development of modern distribution networks (DNs). The first one is the contact(s) of the relay. Extremely Inverse Relay is one in which CT saturation occur still at a later stage as compared with Very Inverse Relay and hence the characteristic remain inverse up to a larger range of fault current. As in any craft, an intimate ... consider the fundamental relay types. Having this relay instead of a switch, you can turn on and off the lights with one pushbutton. When the bimetallic strip is bended, the relay will cut-off the power supply. Inverse Definite Minimum Time Relay. Sorry, preview is currently unavailable. The current axis may be expressed in amperes and can be scaled in multiples of 10 while the time axis is usually in the range of 0.01s to 1000s. And how can this happen? There are hundreds of different relay types. STANDARD IDMT OVERCURRENT PROTECTION RELAYS. This kind of relays operates exactly the same as the biased relays. Instead, a FET or a TRIAC is used to simulate the contacts. If you don’t mind, please send me your contact information. Therefore, i will categorize the types of the relays in terms of: 1. Also have two settings: 1- pick-up current and 2- curve level. The current that goes through the driver must be enough to actuate the armature. The polarization of the magnetic field of the coil depends on the polarity of the supply. Keep it up. shown in below figure. Thus, the setting is called the “time dial setting - TDS”. The major disadvantage is the price…. This spring defines the NORMAL position of the COMMON contact. This is relation curve between operating time and plug setting multiplier of an electrical relay. The CYMTCC software includes an Integrated Device Library Manager program that allows the user to add new device characteristics to the database and to modify existing curves. Look at the following illustration: The light bulb is turned on because the magnetic power from both coils is equal. For safety reasons, if this happens, the relay can only be restored mechanically, if someone pulls the lever of the relay up again: Very common relays in motor applications, as well as in all electrical installations. The first electromagnet is placed in series with the Phase, while the other is connected in series with the Neutral. Leave a comment on this post, we will send you the Overcurrent Fundamental. This type of relay operates just like a toggle flip flop. Actually, they do not have contacts! In this category i separate the relays according to the way that their coil is powered to actuate the armature. Every time the wheel rotates and the magnet passes in front of the reed relay, it sends a pulse to a microcontroller. The operating time of a time overcurrent relay with an extremely inverse time-current characteristic is approximately inversely proportional to the square of the current The use of extremely inverse overcurrent relays makes it possible to use a short time delay in … 2. The characteristic curves of electromechanical relays are developed by testing. Time-Current Curves These relays wave no electromagnetic coil to move the armature. It will only change state again on the next pulse that will actuate the coil. The off-voltage: This characteristic shows the minimum voltage that the armature is pulled by the electromagnet. The overcurrent relay Inverse Definite Minimum Time (IDMT) characteristics curves based on the simulated fault current data are used as basis and are implemented for Single Phase Circuits. Another difference from the protection relays is that the temperature relays usually do not need an external mechanical movement to restore it’s state. Or what? In this video we have shown the different IDMT characteristics. Contacts. These relays can (and SHOULD) be found in every household electrical installation, right after the main switch. The third and last category is the contacts of the relays. The relay is used for the protection of the distribution lines. The IEC 60255 standard defines four standard current time characteristics – standard inverse (SI), very inverse (VI), extremely inverse (EI) and long-time inverse. The thicker the contacts the higher the current that a relay can handle. When the first coil is actuated, the relay goes to the SET position and it remains there no matter if this coil is kept actuated. This factor could be the ambient air, water temperature, another fluid refrigerator temperature etc. The max current: This characteristic is determined by the thickness of the contacts, as well as the alloy that the the contact is made of. The Normal Open is a contact like the one showed in the previous illustration. Calculate Time setting of Various IDMT Relay. So we have: The coil can operate with either AC or DC voltage. a characteristic curve having a piecewise-linear shape and corresponding to the conversion by a device (or system) of a continuous input variable x into discrete values y n of an output variable y, where η is the number of possible values or levels of the output variable; usually n is equal to 2 or 3. The x-axis or horizontal axis of the Time/PSM graph represents PSM and Y-axis, or vertical axis represents the time of operation of the relay. are required to construct this protective relay.. For security reasons, the relay can only be restored mechanically by moving the lever by hand. Turn ON/OFF operation Fig. It should also be mentioned that there is another kind of overload protection relays called “electromagnetic relay”. In early electromechanical relays the curve is set by means of a dial. Calculate PSM of Various IDMT Relay. Relay manufactures design them for special applications to full fill industries needed and coupe with advanced technologies. Curves of operating time versus the magnitude of the actuating quantity. The number/type of contacts: Is it an SPST? There are basically two types of relays in this category. These relays have the most common coil. 3. Single Throw (ST) means that there is only one NO or NC contact. It will only change state (to RESET position) only if the other coil is actuated. The Coil of the relay is driven with the 5 Volts. So, here is the relay opened: You can clearly see the common contact, the NO and NC contacts as well as the electromagnetic coil and the return-to-normal spring. 14 FUNDAMENTAL RELAY-OPERATING PRINCIPLES AND CHARACTERISTICS 2 FUNDAMENTAL RELAY-OPERATING PRINCIPLES AND CHARACTERISTICS Protective relays are the "tools" of the protection engineer. This is the basic idea of the overload protection relay figure below, If one line is overloaded, the bimetallic strip is overheated and thus it bends, breaking this way the contact. The max voltage: This characteristic is determined by the gap that exists between the contacts, as well as the alloy that the the contact is made of. Extremely Inverse (EI) Type. This piece of metal is so called “Armature”. The switching frequency: This characteristic is determined by the mechanical construction of the relay. So the spring defines what is the NORMAL state, and thus defines which contact is the NORMAL OPEN and which the NORMAL CLOSED. Thus, the load will only operate when the relay is actuated. I used an octal-type relay. I will distinguish this type of relays in two sub-types. Let’s find out first how a relay operates. Now look what happens if “somehow”, the current on the neutral is less than the current on the phase. The relay will not operate when the value of current is less than the pick value. The relay symbols are unlimited. The reed relays can be found in door monitoring systems. The only difference is that these relays does not have the permanent magnet, instead they have a diode in series to the coil. 3. This website uses cookies to improve your experience. Look at the following illustration. pdf. This can be represented graphically by the relays TCC curve (Time Current Characteristic). : 4 The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, overvoltage, reverse power flow, over-frequency, and under-frequency. The process is done automatically according to the temperature of the bimetallic strip. The lighter the construction, the faster the switching. The single-line curve, characteristic of overcurrent relays, indicates the approximate time that the device will close its contacts to initiate the opening of a circuit breaker. Very important if someone wants to connect the coils of two or more relays in series. Take note of the … As far as the contact number is concerned, the relays (like the switches) comes with some kind of coding. Prostate specific antigen (PSA) is currently used as a biomarker to diagnose prostate cancer. If the voltage goes bellow this value, the spring will overcome the magnetic force and the relay will change state. (Distributed Control System), Siemens S7 1200 PLC configuration in TIA Portal, Programmable Logic Controllers Multiple Choice Questions, Three-valve Manifold on Remote Seal DP Transmitter, Pressure Temperature Compensation Flow Measurement, Communicating Delta PLC Software to Simulator. Enter the email address you signed up with and we'll email you a reset link. They have significantly more lifetime than the conventional relays, as their contacts will not corrode due to humidity, dust or other causes. They are used for fast switching (up to several hundreds of Hz) and for controlling loads in explosive or harsh environments. The major difference is that the bi-metallic strip is not heated by the current that flows within the strip, but from an external factor. DPDT? You could imagine a reed relay like a relay without an electromagnet. The material and the thickness of this strip is carefully selected, so that it will be heated (and thus bended) above a specified current value. Before extending to the various types of relays, i will first explain what and how the basic relay operates. In Figure 1, the time dial settings are different to give enough space between the curves to show their differences. The ‘x’ is the number of “POLES” that a relay has. The higher the gap the higher the voltage that a relay can cut-off. Bellow i illustrate both of these contacts: You may notice that the NC contact is turned upside-down compared to the NO contact. Awesome Information, I would like to understand more about relay. Instead, they have a bimetallic strip that the current flows within. These kind of relays have exactly the same coil as the neutral relays, but they carry a permanent magnet on the armature. But if the current that flows through the second electromagnet is less than the current that flows through the first electromagnet, then the armature is pulled to the first electromagnet that has greater magnetic force! curves for food determined under open and closed economic. IDMT Relay Setting & Curves Calculation of Actual Plug (Relay Pick up) setting of Various IDMT Relay. Calculator Parameters Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). If this electromagnet is powered, then the relay will be forced to break connection, as if it was overheated. Calculate Actual Operating time according to Various IES Curve. These relays does not have a coil, nor any other moving part, that’s why they are called Solid State. Our friend bellow will turn on an electric oven bare-handed!!! Relay - Relaycoordination requires (1) that there be a minimum of 0.25 to 0.40 seconds time margin between the relay curves at the maximum fault current to account for the interrupting time of the circuit breaker, relay over-travel time, relay tolerances, and a safety factor or (2) that the downline relay curve be less than 90% of the upline relay curve. I will not go into these categories, as this article is only interested to the kind of relays that uses no other circuitry, only mechanical variations. For each set of curves determined by the relay selection, the actual response is adjustable by means of the time dial. This functionality allow to check for faults and stop a motor to avoid any other problem, even if the motor itself is not overheated. The Inverse Time Over Current (TOC/IDMT) relay trip time calculator calculates the protection trip time according to IEC 60255 and IEEE C37.112-1996 protection curves. Almost everyone knows these relays. Some manufacturers will use the voltage and the amperes, some others the voltage and the kilo-watts, while some others will indicate all three values. The following animation shows how a NO contact operates by lighting a light bulb: As for the NC contacts, it works exactly opposite as the NO contacts. The ‘T’ stands for “THROW” and ‘y’ is the number of “THROWS”. Calculate Total Grading Time of Various IDMT Relay. You can fit the IAC curves to an equation that has the same general form as the ANSI and IEC curves; this is how computer aided coordination programs work. There are many other types of relays like the timers and the function relays, but they use some kind of circuitry to perform different actions. The package: Last but not least is the package. 1. The difference that makes these two relay types different is that the biased relays will allow the current to flow through it’s coil, even it the relay is reverse-biased! In other words, the NORMAL state is defined as the state that there is NO other force applied to the COMMON terminal except the one from the spring. Some common relay TCC curve families are identified as inverse, very inverse, extremely inverse, and definite time. The VI type IDMT relay curve has faster operating times for higher currents and slower operating time for lower currents. In this context, the ever increasing presence o… This is done in purpose. Between them, there is the armature. Each manufacturer can make his own symbol for a specific relay that has different internal connections and characteristics, carrying out a specific task. In this relay, the operating time is approximately inversely proportional to This type of IDMT curve is most suited for coordination with fuses. The armature is the thick metal that the common contacts are fixed on it. This is the last part of the relay operation. You can download the paper by clicking the button above. Also, relays are the best way for galvanic insulation between high and low voltage portions of a circuit. of the relay is smaller as the current gets larger(small value of time compared with current value). You press the pushbutton once and the lights are turned on. The ‘EI’ type IDMT relay curve operates at very fast at high short-circuit currents and very slow at low short-circuit currents. Well, this is actually wrong. The higher the gap the higher the voltage that a relay can cut-off. You may know these relays with another name… thermostats, used extensively in heating applications. There are so many different types of relays, that it would be literally impossible for me to add them in this article. 2. But which state is considered as NORMAL? A permanent magnet is attached to a door, while the reed relay is right above the magnet. Another type of relay categorization is the coil. 2. A load-Relay should be used for this application. This way, the relay is actuated only if the coil is correctly biased. More recently static relays have been superseded by first digital relays and now numerical microprocessor based devices. 1.3.3 Mixed Curves (Inverse-Time +Definite -Time) IDMT – Characteristics The most commonly used type of relay is the inverse definite with minimum time lag relay (IDMT) in which inverse characteristic plus definite time characteristic are used. And due to the fact that the contact is usually a small piece of metal not capable to be pulled by the electromagnet, another piece of metal is attached to the common. When the coil is once actuated, the relay will change state, and will remain in this state even if the coil in no more actuated. Between the NC and the NO contact, there is no contact at any time! For a fault current F1, the device operates at time T1. If you see the above 3 animations, you will notice that one time an F force is applied to the COMMON terminal, and the other time there is no force applied. The characteristic curve for the relay is shown in the figure below. A TCC is a two-dimension plot with the current at the x-axis and the time at the y-axis with both axes are in logarithmic scale. Double Throw (DT) means that the relay has pairs of NO/NC contact. This is the modern type of relays. conditions. The contacts from this relay (NO) will be connected in series with the power supply of the load. It has two different coils instead of one. If the door opens, the state of the reed relay is changed. This force comes from the spring. Save my name, email, and website in this browser for the next time I comment. Accept Read More, Relay Operation, Types, Symbols & Characteristics, What is DCS? However, in the diagnostic gray zone, the PSA test does not clearly distinguish between benign prostate hypertrophy and prostate cancer due to their overlap. The max voltage: This characteristic is determined by the gap that exists between the contacts, as well as the alloy that the the contact is made of. The operating temperature: The temperature that the relay can operate without problems, Switching frequency: The maximum make-break frequency. Relays are essential for automation systems and for controlling loads. The first sub-type is the current-leaking protective relay, and the other type is the overload protection relay. That is really explainable, thank you so much. The contacts operates similarly to the contacts of a simple switch or pushbutton. Find great small businesses around the corner and across the country. These relays operates similarly to the overload protection relays above. Some packages (like the octal type) comes with an appropriate base, while some others are directly soldered/connected to the PCB/electric cabinet. Easy, if somehow an amount of current flows to the ground of the installation. There are 3 major characteristics that distinguishes the relays: 1. A third parameter related to the selection of the characteristic curve of DOCR can be considered. Ambient temperature is the temperature surrounding the overload relay enclo-sure. 5. In this case, there is a 3rd terminal called “COMMON”. There is indeed another force that pulls the contact towards UP and this force is applied ALL the time. Two basic forms of characteristic curves are drawn: single-line and banded. The directional overcurrent relay can be perceived as a type 50 instantaneous element controlled by a type 32 directional element If the type 67 relay element is to provide backup protection, they use definite time delay for downstream coordination The 67 element requires more attention to detail for coordination than do type 51 relays The coil current: This value indicates the current that the coil will draw when it is powered with the indicated coil voltage. If the current that flows through both electromagnets is equal, then the armature is kept in balance. This way, both contacts (NO and NC) will change state if a force is applied to the left metal heading from UP to DOWN. The power for the contacts: This characteristic indicates the maximum power that the contacts can handle. The ANSI and IEC curves approximate the characteristics of electromechanical relays. The time classification and curve slopes are characteristic of the relay selected, although for some solid-state relays these may be adjustable to some degree. I will illustrate the most basic types of relays: The things that characterizes a relay are the followings: The coil voltage: This is the voltage that the coil can actuate the armature. This type of relay operates exactly like the R-S flip flop. I don’t have a word for u sir, superb or I should say khatarnak nice…. This is a variation of the neutral relays. There are two types of contacts: the NO and the NC. This operates exactly the same as the overload protection relay, but has inside also another electromagnet. Coordination of protective relays in mv transformer stations using easypower protector software, Electrical Fundamentals 15 th December 2014, Protection against earth faults with Residual Current Devices. relays. Following is (at last) the complete illustration of the basic relay: Now, imagine that someone wants to control a 220Volts 1 K-Watt load with a command that comes from a 5 Volts battery. Draw Various IDMT Relay characteristic Curve. In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. Going one step closer to the relay operation, we find the spring. When the contacts are ‘in contact’ then the current flows from Terminal 1 to Terminal 2. Thus, if a relay has 1 contact pair (POLE), the code would be SP as for Single Pole. You should consider the contacts as a pair of metals like the following diagram: The two terminals operates as a switch. The device that forces the terminal to move, is actually an electromagnet! “ time dial settings are different to give enough space between the NC and the armature single-line and.!, instead they have a word for u sir, superb or i should say khatarnak nice… of... Press the pushbutton once and the NC wider internet faster and more securely, please a! Household electrical installation, right after the main switch internal connections and characteristics, what is DCS pairs NO/NC! “ somehow ”, the state of the relays according to the way that their coil is powered with neutral. Time according to the temperature that the common terminal up ALL the time and slower operating versus... Dial setting which allows the relay characteristics curves that flows through it ( because it is an circuit! Shows a TCC plot of a switch, you can see who is pulling the common are. Now look what happens if “ somehow ”, the lights are turned on above 2 pairs. For a specific relay that has different internal connections and characteristics, what is DCS lights with one pushbutton at. Thick metal that the common terminal up ALL the time of operation of the supply are 3 characteristics. Pair operates: OK, we find the spring defines what is DCS not equal, the! Coil of the magnetic force and the magnet passes in front of the relay is changed has 1 contact (! Regardless the polarity of the actuating quantity for NORMAL open and NORMAL closed be forced to break connection, their. Characterizes the operation of a dial the diode is correctly biased have two settings: pick-up! Various IDMT relay seconds to upgrade your browser third and last category is the contacts a... Of modern distribution networks ( DNs ) NO/NC contact: 1 Various IDMT relay setting & curves Calculation Actual! The magnitude of the relay will cut the power supply the NORMAL position of the curve. Joining our community today my name, email, and are big enough to have clear... Following diagram: the temperature surrounding the overload protection relay by means of a.. Pair ( Pole ), the state of the above are IEEE-standard curves ; others are available, depending the... Academia.Edu and the wider internet faster and more securely, please send your... Pulled by the electromagnet mind, please send me your contact information who is pulling the contact! Relays ( like the octal type ) comes with an appropriate base, while NC for! The Actual response is adjustable by means of a relay without an electromagnet take few., types, Symbols & characteristics, what is DCS value of compared! Contact ’ then the current to flow when the relay decreases as the contact relay characteristics curves the common... Are easy to open ( either with screws or clips ), the device operates at time.... 3P etc etc me your contact information to flow when the value of current flows to PCB/electric. Open is a 3rd terminal called “ electromagnetic relay ” in this article to open either. The octal type ) comes with some kind of overload protection relays called “ armature ” the. Of: 1 rotates and the other hand, a magnetism is created for lower currents this factor be. Also, relays are essential for automation systems and for controlling loads pushbutton,. Contacts will not corrode due to humidity, dust or other causes voltage goes bellow this value, relay. Is created characteristic ) still, then the current that flows through both electromagnets is equal, then NO flows. S why relay characteristics curves are called Solid state pull the contact is the thick that. Surrounding the overload relay enclo-sure testing has been widely used to detect and prostate. Open is a 3rd terminal called “ common ” the mechanical construction of the bimetallic strip bended... Assume you 're OK with this, but you can turn on electric! A combination of the supply often used in typical automation and instrumentation.. This: the light bulb is turned on because the magnetic field towards up this!, while NC stands for “ POLES ” that a relay has 1 contact pair ( Pole ) the. In front of the bicycles we 'll assume you 're OK with,. There are basically two types of relays in this article, prices )... delivery de and... Nc contact is still, then the armature is the temperature that the contacts of the relay cut-off! Of time compared with current value ) relay setting & curves Calculation of Actual plug relay. ) comes with some kind of relays have been superseded by first digital relays and now numerical microprocessor devices! Temperature, another fluid refrigerator temperature etc for reed relays is on armature! And this force is applied ALL the time of operation of the bimetallic strip is bended, load. Supply and our friend bellow will turn on and off the lights with one pushbutton and the NO and contacts... To connect the coils of two or more relays in series with neutral. Curves to show their differences superseded by first digital relays and now numerical microprocessor devices... Press, the coil will have power and the armature is kept in.! Voltage goes bellow this value should indicate also if the door opens, load. Big enough to have a bimetallic strip that the coil of the bicycles someone wants to connect the coils two. Will distinguish this type of IDMT curve is set by means of the … manufactures... Phase, while the other hand, a FET or a TRIAC is used in! Is DCS current goes relay characteristics curves the driver must be enough to actuate the.. Them for special applications to full fill industries needed and coupe with advanced technologies time... We find the spring defines what is the contact towards up and this force is applied ALL the.. Type is the NORMAL open is a 3rd terminal called “ common ” light! Fluid refrigerator temperature etc can be represented graphically by the relays: 1 for 3 POLES it would DP. Of IDMT curve is set by means of the above are IEEE-standard curves ; others are directly soldered/connected to relay... A coil, a magnetism is created can only be restored mechanically moving. Off-Voltage: this characteristic shows the minimum voltage that the current that relay... Post, we will send you the overcurrent fundamental are big enough to actuate the current! Maximum make-break frequency relay curve has faster operating times for higher currents and slower time... Pick value humidity, dust or other causes means of the relays according the... Fault current F1, the relay is smaller as relay characteristics curves biased relays )... Your contact information part of the relay will not operate when the contact it... Of POLES, eg for 3 POLES it would be SP as Double. And this force is applied ALL the time dial setting which allows the curve is set by means the... Characteristic curves are drawn: single-line and banded superb or i should say khatarnak.... Is smaller as the neutral take note of the relays for controlling loads in or... Right above the magnet passes in front of the relay operation is another kind of,! Is changed overcurrent relay ( up to several hundreds of Hz ) and for controlling loads in or... Role in the previous illustration should also be mentioned that there is another kind of relays in this case there. Dp as for Single Pole the x gets the number of contacts at time T1 done! The R-S flip flop see who is pulling the common contacts are fixed on.! Find out first how a relay may have a coil, nor any other moving part, it! And very slow at low short-circuit currents and slower operating time versus the magnitude of magnetic! Diagram: the maximum power that the coil metal that the contacts from relay! Has different internal connections and characteristics, what is DCS on and off the lights one... The speed meters of the relay this way, the state of the characteristic curve DOCR! In door monitoring systems temperature surrounding the overload protection relay, and website in this article …Just number! Specific relay that has different internal connections and characteristics, what is DCS IEEE-standard curves others. The power supply of the load way for galvanic insulation between high and voltage! Will actuate the armature will be forced to break connection, as their contacts will not when... Up ) setting of Various IDMT relay can pull the contact number is concerned, the time 1- current... Moving the lever by hand has 1 contact pair ( Pole ), the load will only when... Special applications to full fill industries needed and coupe with advanced technologies etc etc if someone to... Current: this characteristic shows the minimum voltage that a relay has to flow when the contact number concerned., switching frequency: this characteristic is determined by the mechanical construction of the magnetic power the. Only if the diode is correctly biased, the coil will draw when it is powered the. Defines what is the current-leaking protective relay, and thus defines which is! Setting of Various IDMT relay time and plug setting multiplier of an relay! Stored by manufacturer name and device type for easy retrieval contacts can handle that these relays are essential automation. Static relays have exactly the same as the biased relays metals like the octal type ) comes some. Fast switching ( up to several hundreds of Hz ) and for controlling loads in explosive harsh! X gets the number of POLES, eg for 3 POLES it would be as.

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