Instantaneous over-current relay. The Directional Overcurrent element needs a polarizing signal to operate reliably; otherwise anything could happen depending of the sophistication of the relay. Module-4 Overcurrent Protection. The varying pick-up level makes it more difficult to co-ordinate the relay with other fixed pick-up overcurrent … At 25 percent voltage the relay picks up at 25 percent of the relay setting (1.75 0.25 = 0.44 times rated). 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 relay operates for the defined direction when the fault current is in the same direction and exceeds the over current setting value. 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. 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. EHV system is an Interconnected Network System of Circuit Element, having more than one Voltage Source. 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). Defination: Overcurrent Relays respond to the threshold value of the current i.e. RE: Overcurrent Relays - Tap Setting vs. 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 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. 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. Low Voltage Breaker - Fuse coordination requires a minimum 0.1 second time margin between the … Current setting is the setting of current(pick-up current) in a relay at which we want to operate that relay. A. B. 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. If the fault current is larger than the overcurrent setting, the relay will trip. Hence, this relay has current setting range as well as time setting range. 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 Example1: Determine the PSM (plug setting multiplier) of a 5A, 2.2 sec over current relay having a plug setting P s =200%. Fuse - Relay coordination requires a minimum 0.3 second time margin between the curves. 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. 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. For example, the relay can be set for 175 percent of generator rated current with rated voltage applied. A relay that operates or picks up when its current exceeds a predetermined value (setting value) is called Over-current Relay. 13 An IDMT type over current relay is used to protect a feeder through 500/1A CT. The supply CT is rated 400:5A and the fault current is 12000A. Distance Relay. Introduction 3.1. Overcurrent Relay Technical Reference Manual 3. 3. Curve - Select the Curve setting of the time overcurrent relay.. If we clear the concept for these relays first then understanding the Numerical Relay settings becomes easy. To understand this concept easily, it is better to know about settings of the Electromechanical Relays. The REJ 523 is based on a microprocessor environment. The overcurrent unit continuously measures the phase currents of the object. More recently, dual-setting over-current relays are evolved as competent countermeasures for such cases. The MTA setting is commonly thought of in terms of the forward-looking line impedance angle. This should be 0.50 - 15.00 for U.S. curves and 0.05 - 1.00 for IEC curves. Consequently, additional protective measures are needed here. The overcurrent relay REJ 513 is a secondary relay which is connected to the current transformers of the object to be protected. 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 Calculation of IDMT Over Current Relay Settings (50/51/50N/51N) Calculation model for thermal relay Siemens 7SJ64 Fault Current - Enter the Fault Current for which the operate time should be calculated. We refer the pre-set value of current in the relay coil as pickup setting current. Successful in coordinating and implementing the IDMT MK2000 relay in … Table 2 details the calculations associated with setting of overcurrent relays. 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 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. 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. In this way, establishing an optimal coordination strategy is recognized as the first prerequisite in assuring a safe protection scheme. is 400/5, then the plug setting multiplier should … The characteristic angle is the phase angle by which reference or polarising voltage is adjusted such that the directional relay operates with maximum sensitivity. The fault analysis that will be study only for over current, short circuit and earth fault, 1.5 Expected results . The basic element in overcurent protection is the overcurrent relays. Pickup - Enter the pickup setting of the time overcurrent relay in primary amps.. Time Dial - Enter the Time Dial setting of the time overcurrent relay. Fig. 0 to 30 s (The startup lock timer starts when the input has reached approximately 30% or more of the set value.) It shows both the minimum fault current and the maximum load current. 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 […] 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. 9. 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. 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. Operating time setting range (T) 0.1 to 30 s Startup lock time setting range (LOCK) Note: Enabled only for overcurrent operation. A type of relay in which the time of relaying varies directly as the distance of the fault from the station . Note: Enabled only for overcurrent operation. 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. once the current through the relay goes, beyond the set Value, it operates ANSI Code : Its ANSI Code is 50. Therefore a setting of 20% should prevent the relay from switching to the more sensitive characteristic on a low-voltage fault. Better to know about settings of the forward-looking line impedance relays ( 21 ) to a. ( 21 ) to prevent a situation like this from occurring from station. Relays ( 21 ) to prevent a situation like this from occurring calculations much easier Siemens 7SJ64 Fig details. 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