Most electro-mechanical relays, and GE relays like the one from The Relay Testing Handbook example, use the phase-phase voltage from the two un-faulted phases as a polarizing signal. The over current relay can be used as overload (thermal) protection when protects the resistive loads, etc., however, for motor loads, the over current relay cannot serve as overload protection Overload relays usually have a longer time setting than the over current relays. Lecture -18 Directional Overcurrent Relaying This would be particularly true if the relay simply compared voltage and current from a common phase for a line to ground fault (e.g., I A is compared to V AN). 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. The supply CT is rated 400:5A and the fault current is 12000A. Overcurrent Relay Setting Model for Effective Substation Relay Coordination International organization of Scientific Research 27 | P a g e associated with temperature rise of the equipment whose permissible limit is based on insulation class and material problems. The MTA setting is commonly thought of in terms of the forward-looking line impedance angle. Overcurrent Coordination Page 3 Qual-Tech Engineers, Inc. 8. Operating time setting range (T) 0.1 to 30 s Startup lock time setting range (LOCK) Note: Enabled only for overcurrent operation. 0 to 30 s (The startup lock timer starts when the input has reached approximately 30% or more of the set value.) Consequently, additional protective measures are needed here. Overload relay is the one of important device for motor control.It can prevent our motor from overheat or winding burning due overload of ampere. If we clear the concept for these relays first then understanding the Numerical Relay settings becomes easy. The relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. A definite time over-current (DTOC) relay is a relay that operates after a definite period of time once the current exceeds the pickup value. In this way, establishing an optimal coordination strategy is recognized as the first prerequisite in assuring a safe protection scheme. Breaker Failure If after a programmable time delay, the circuit breaker has not opened, breaker failure protection issues a trip signal to isolate the failure breaker by tripping other surrounding backup circuit breaker. The REJ 523 is based on a microprocessor environment. The basic element in overcurent protection is the overcurrent relays. Fuse - Relay coordination requires a minimum 0.3 second time margin between the curves. 3. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. The fault analysis that will be study only for over current, short circuit and earth fault, 1.5 Expected results . Calculation of IDMT Over Current Relay Settings (50/51/50N/51N) Calculation model for thermal relay Siemens 7SJ64 We refer the pre-set value of current in the relay coil as pickup setting current. Lecture -14 Fuse Protection; Lecture -15 Fundamentals of Overcurrent Protection; Lecture -16 PSM Setting and Phase Relay Coordination (Tutorial) Lecture -17 Earth Fault Protection using Overcurrent Relays; Module-5 Directional Overcurrent Protection. EHV system is an Interconnected Network System of Circuit Element, having more than one Voltage Source. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current Relay. Therefore a setting of 20% should prevent the relay from switching to the more sensitive characteristic on a low-voltage fault. 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. 51P1T Phase Time-Overcurrent Element Curve Timing and Reset Timing 51P1P 51P1C 51P1TD 51P1RS 51P1CT 51P1MR Settings Relay Word Bits 51P1P 51P1T 51P1R Controls the Torque Control Switch Instantaneous over-current relay. It shows both the minimum fault current and the maximum load current. Solution: I p 12000A I s 150A 400 5 12000 u On PS of 200%: The relay current 10A 100 200 5u Hence PSM 15 10 150 Overcurrent Relay Technical Reference Manual 3. 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. RE: Overcurrent Relays - Tap Setting vs. Overcurrent relay. A type of relay in which the time of relaying varies directly as the distance of the fault from the station . Current setting is the setting of current(pick-up current) in a relay at which we want to operate that relay. is 400/5, then the plug setting multiplier should … Curve - Select the Curve setting of the time overcurrent relay.. This project should be: Successful in setting the IDMT MK2000 relay for over current protection in the system. However, when quadrature The relay has a Plug Setting of 125% and TMS=0.3.Find the time of operation of the said relay if a fault current of 5000A flows through the feeder. The varying pick-up level makes it more difficult to co-ordinate the relay with other fixed pick-up overcurrent … This should be 0.50 - 15.00 for U.S. curves and 0.05 - 1.00 for IEC curves. Use of the relay The overcurrent relay REJ 523 is intended for selective short-circuit protection in medium voltage distribution networks but can also be used for protection of generators, motors and transformers. Note: Enabled only for overcurrent operation. Example1: Determine the PSM (plug setting multiplier) of a 5A, 2.2 sec over current relay having a plug setting P s =200%. The Directional Overcurrent element needs a polarizing signal to operate reliably; otherwise anything could happen depending of the sophistication of the relay. For example, the relay can be set for 175 percent of generator rated current with rated voltage applied. This indicates for any fault causes over current in the earth element of the relay that exceeds the setting value. Low Voltage Breaker - Fuse coordination requires a minimum 0.1 second time margin between the … Model overcurrent overcurrent or earthfault boards size † inst † inst † inst MCGG 22 14 MCGG 42 26 MCGG 52 38 MCGG 53 28 MCGG 62 36 MCGG 63 16 MCGG 82 48 Application The relay can be used in applications where time graded overcurrent and earth fault protection is required. The overcurrent unit continuously measures the phase currents of the object. B. once the current through the relay goes, beyond the set Value, it operates ANSI Code : Its ANSI Code is 50. Now ideally, one can set the pick up current of the overcurrent relay anywhere within the maximum feeder load current (column 2) and minimum fault should not allow PSM to be below 1.5. Introduction 3.1. Over Current Protection: It finds its application from the fact that in the event of fault the current will increase to a value several times greater than maximum load current. The overcurrent relay REJ 513 is a secondary relay which is connected to the current transformers of the object to be protected. In this case, the relay is sensing Z A between the relay and the fault. Directional overcurrent protection schemes were replaced with line impedance relays (21) to prevent a situation like this from occurring. Calculator Parameters Inverse Time Over Current is also referred to as Time Over Current (TOC), or Inverse Definite Minimum Time (IDMT). Fault Current - Enter the Fault Current for which the operate time should be calculated. A. The Reyrolle 7SR10 Argus overcurrent and earth fault relay is developed using the latest generation of hardware technology and is available in multiple variants depending on the power supply, binary input/binary output configuration and data communication facility. 4: Network map with non-directional, maximum-overcurrent time protection relay. 13 An IDMT type over current relay is used to protect a feeder through 500/1A CT. Hence, this relay has current setting range as well as time setting range. The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. Tap Range dpc (Electrical) 13 Aug 12 18:36 In general, the tap range is fixed based on the relay model, not a setting you can change. More recently, dual-setting over-current relays are evolved as competent countermeasures for such cases. If the fault current is 2000 amps, the relay setting is 50% and the C.T. This relay is referred as instantaneous over current relay, as ideally, the relay operates as soon as the current in the coil gets higher than pick upsetting current.There is no intentional time delay applied. We need to setting the value of overload relay properly depend on our application and motor full load ampere.If we setting low from FLA,it can cause motor trip c0ntinues and process […] Distance Relay. relay settings, over current relay settings, idmt relay setting, earth fault relay setting, instantaneous relay setting, how to set relays, relay setting calculation, relay characteristics, calculation to set relays, IDMT relay setting calculation These spreadsheets below will make your endless calculations much easier! Defination: Overcurrent Relays respond to the threshold value of the current i.e. If the fault current is larger than the overcurrent setting, the relay will trip. At 25 percent voltage the relay picks up at 25 percent of the relay setting (1.75 0.25 = 0.44 times rated). The tappings are connected to plug setting bridge.With the help of this bridge, the number of turns of the primary winding can be adjusted.Thus the desired current setting for the Non-Indirectional Induction Overcurrent Relay can be obtained.There are usually seven sections of tappings to have the overcurrent range from 50% to 200% in steps of 25%. Successful in coordinating and implementing the IDMT MK2000 relay in … Module-4 Overcurrent Protection. 9. Table 2 details the calculations associated with setting of overcurrent relays. Fig. On the 50/51 overcurrent relay, the time-overcurrent-element (device 51) setting is made by means of a plug or screw inserted into the proper hole in a receptacle with a number of holes marked in CT secondary amperes, by an adjustable calibrated lever or by some similar method. 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