overcurrent protection pdf

However, these traditional methods do not always meet the design criteria; Overcurrent protection is a selective type of overload and short circuit protection, used mainly in radial networks with single ended feeders found in medium voltage systems. 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 … Before addressing those requirements, let's review the basic concept of overcurrent protection. 2. 3h�c�G;����RL�ё "��N���[�v��aR�|:cR �=�kX9�7�: Magnetic circuit breakers, fuses and overcurrent relays are commonly used to provide overcurrent protection. 0000000930 00000 n Circuits can be designed to meet many of the automotive, military, and avionic standards including ISO 7637-2, h޼Xmo�8�+�^ѻd`����[�k�lk7���q�3$���đ�\����$K�$>�CYƙ�LH��cR+&���L�{��R[�K&=7L;��L{��͘���N>c:��e��8{�zp�/��yU�g�g�'w���%�=��:�Ϧ��b�XTӼ���������z�O����rZTuY?���=}��� ���d��*�S���1�^�/Gm������jVGhֻ4��|���=�(fu���z;�`�e1]+�\V�jY����bY���/��4%.sQ����i�ʛB؍�������@Ѵ���* g����R�ʆ��� ��#ԭM��Z�_�W���:� 3I)����.�����[��?�ON�rV:�7��n �� The following table shows a summary of fault duties and how they are used. Overcurrent protection is designed to protect the system from the intolerable conditions associated with short-circuits. Overcurrent Protection - Free download as Powerpoint Presentation (.ppt / .pptx), PDF File (.pdf), Text File (.txt) or view presentation slides online. endstream endobj 20 0 obj<> endobj 21 0 obj<> endobj 22 0 obj<>/Font<>/ProcSet[/PDF/Text/ImageB]/ExtGState<>>> endobj 23 0 obj<> endobj 24 0 obj<> endobj 25 0 obj<> endobj 26 0 obj<> endobj 27 0 obj<> endobj 28 0 obj<>stream Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to trip when the line current becomes excessive. 0000020534 00000 n �"�����QN$�u����6|Fk*ɑ"�R(x��]�#�wd��ϨAD�, �Ds��E� ^o�_'̋{��Օ������ #�%-�ċ�,�#� In the feeder with small impedance, disting… Figure 1 shows the single line diagram of the radial network. PDF Version. ],�Xt��b�Ţ�E�>�6�o�� Kk�,#�&�m,0 h�} As shown in Figure 5, the electrical power distribution system within … h��]O�0��S|9.��N2�J�T���vڴ 0 0000017975 00000 n trailer If the 0000001139 00000 n Put the switch 1 and 3 off and switch 2 off. The relay located furthest from the source, operates for a low current value. endstream endobj 29 0 obj<> endobj 30 0 obj<> endobj 31 0 obj<>stream of Overcurrent Protection from the mid-1960s until his passing in 2015. The branch-circuit overcurrent protection device must be sized not less than 125% of 53 amperes, So, branch-circuit overcurrent protection device size = 53 amperes x 125% = 66 amperes. STANDARD IDMT OVERCURRENT PROTECTION RELAYS. endstream endobj 164 0 obj <>stream Primary protection should be fast. %%EOF Uncorrected “overcurrent” can cause serious safety hazards and costly damage to electrical equipment and property. ������g��a{8����(6hj���#n�(�؅�u_�zN6�t�K�@��8*���LP����9\*y��Y^A��z.B{��Оn��"�jE%�jM�@=�T��q�}W͜_�i^����K��������� 8�3����!"��Ҡܹ�? Two fundamental requirements of protection are as follows: 1. This scheme is based on the intuition that, faults typically short circuits, lead to currents much above the load current. Transmission Line Protection Directional Overcurrent Protection Relay responds to overcurrent condition in the forward direction only (device #67, 67N, 67NT) Will not respond to reverse faults Compares the current in the line versus a known reference that will always be the same (such as a … 0000001701 00000 n This paper will review the mainstream methods by which 67 type directional decisions are made by protective relays. Power system Protection Part – 5 Dr.Prof. Connect the circuit shown in Figure 13. Abstract – Directional overcurrent relaying (67) refers to relaying that can use the phase relationship of voltage and current to determine direction to a fault. x�b```c``�``a`sf�g@ ~�+sl```ԒY!�� T&p)�”m&M��]����� i@IF Vd�20�FiA k�a�e\!�� #P������홾>/��'7���Z�����H3�5X3c�U��@| � �� %PDF-1.6 %���� This relay is referred as definite (instantaneous) overcurrent relay. 19 20 162 0 obj <>stream <]>> When current exceeds Protecting circuits and equipment from overcurrent from overcurrent involves more than simply selecting a fuse or breaker from a table Art. *qr�JPy?���.̟r6����x���a�Y��p m��a!��������ȸ�8&�IbR�4&tQ��E��B�. 5. ux��7!�w4��>B�)1^����-� &�]!5b�i,M�h㮅��T���. 2.3 Mixed Curves Over-Current Relays Mixed curves have all the advantages of the different types of over-current relays. The relay operates as soon as the current gets higher than a preset value. 0000000016 00000 n 0000001010 00000 n pdf. View Lab Report - Exp 5- Overcurrent Protection of Transmission Line.pdf from ELECTRICAL EE24569 at Princess Sumaya University for Technology. 0000006233 00000 n 0000002226 00000 n Overcurrent Protection The general requirement for overcurrent protection of conductors is provided in Section 240.4, Protection of Conductors. Among his many accolades, he was awarded the Outstanding Educator Award by the IEEE as a … 5 Overcurrent Protection of Transmission 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. 0000005458 00000 n Back up protection should act if and only if primary protection has failed. Put the load to the maximum resistance 3. 2. �{� �9�pp&��0�j�! 1. initialized. Depending on the time of operation the overcurrent relay is categorized into following types. If the overcurrent persists even after the counter reaches zero, a trip decision is issued. As a licensed professional engineer, he presented seminars on electrical overcurrent protection for more than 40 years. Overcurrent relays are widely used for the protection of transmission and distribution networks [3]. [5��!�j&�qn�dԲ��|�(f��,�R"�pM!���.�l��z����F�d�֌sj��@��L�A���[Z4(�J�ƚZiU0 The overcurrent limits are as follows: • Primary 9 Amps or more: no more than 125% of rated current 0000010267 00000 n h�t��k�0���{ԧ��M"�ك�Һ��=����&��U��$��&�@�܏�L �"���pf0��.\�y&\o&�R��X�C��d��oN�^z�E�X��'��>Mɥ�l�_'ƇJ�yC��G5*g�V�v�ç#pG$�S�=�cT1�+��є���J�����pHIj�vp��2�N�`�{Lз(���$�b�����1���W�6��,65�w���#��H|? provide excellent protection for similar applications. There is no intentional time delay set. Hence, it is intentionally slow. ]4�ht�1}.�y��9pi�y*.�����Տ����:}��?�����1�AhBc��D� z�3��A�. The relay setting is adjusted based on its location in the network. Overcurrent Types and Effects An overcurrent is any current that exceeds the ampere 0000002527 00000 n xref 38 0 obj<>stream That means the circuit can act as an overcurrent or short circuit protection. According to Section 240.6(a) for “Standard Ampere Ratings of overcurrent devices”, we must select a minimum 70 ampere overcurrent protection device. Mohammed Tawfeeq 011 Power system protection Dr.Mohammed Tawfeeq Overcurrent Protective Relays Overcurrent relays Overcurrent relaying is the simplest and cheapest type of protection used for protection of … Overcurrent protection. 0000007916 00000 n There are two options for overcurrent protection: Option 1 (Primary only Protection) Provide an overcurrent device in the primary circuit rated to the current of the transformer. pdf. Overcurrent protection is a basic approach to protect power system equipment from current levels that are beyond the design limits of equipment due to either an overload or a short circuit. Over current relaying and fuse protection uses the principle that when the current exceeds a predetermined value, it indicates presence of a fault (short circuit). There are a variety of concepts by which this task is done. ���` �`�� Information on the available fault duties is important when performing a protection coordination study. The basic rule for overcurrent protection of conductors—other than using flexible cords, flexible cables, and fixture wires—is to protect the conductor in accordance with the ampacities specified in Section 310.15. Lecture -18 Directional Overcurrent Relaying It generally operates instantly. %PDF-1.4 %���� 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 … Leave a comment on this post, we will send you the Overcurrent Fundamental. DIY Short Circuit (Overcurrent) Protection: In this project I will show you how to create a simple circuit that can interrupt the current flow to a load when the adjusted current limit is reached. Over-current protection, OCP for short, is simply a catch-all phrase for the proper implementation of fuses and circuit breakers. overcurrent protection on all control circuit transformers. Figure 13: block diagram for 3-phase system using definite time overcurrent protection. Let's get started! The overcurrent relay is defined as the relay, which operates only when the value of the current is greater than the relay setting time. It protects the equipment of the power system from the fault current. Short circuit is a type of overcurrent. As the over current elements are built as separate units, we may implement the over-current protection principles using: a) a combination of instantaneous and definite-time elements . EA��i2�Y��K��?�]��O��u�V `d�q���m���`]A~*!�5n���0PzK�jj�T`m|W�봉f�MGg��a���\*� 4. 0000000696 00000 n Module-4 Overcurrent Protection. �q�G���[����r�"�$�:$^��������zi�������k�)4���,\�v祧r����]�D,�D����c鳫#sc|�d�fƖ�2)�>h��ە�`�%����_ ��} This provides selectivity. 0000003008 00000 n �5�>��=�h�4ʪ�5�ٹ3@N�^m�K�T��,����h˭*���t�ls�Zޫ%� N�z��c&�y��˧r� ��ԍHDd�4�� �E��e3�b�2�n����}��� �*'�n�vC:�6/�� H��WmK\G�)���]-bR�m�X����%l� mh��5��?h��$�B� A�h��&��MR,f �f��mwg�9s�ݽsW恼�9ϼ�g�9s��!�Lp�[Hx��B�M++ + + BV�k�����I����w�H)KaU�E����`ӏn:J&e����@ͻ�n��;^ð��H)��?L�b���bD��YNXY���%D�j�&Pm� j�(/a4�k͕�yQ�ڒ�e����Hm��Pp�~g��N�Q�D�����e�l. a��~��'�0#��b���z*�mg`s �'0v��yj�W�w,��2�~�P"��XQ��RW�����M:����QӒ�, �v�Ѷ�@}Zk�c����,ms����%4�jת�-��J���>,/�w'��������_�������-Dž;�������"H�R5���o�`=T�#b�ռP����lLʥ��k��j�3��Ae]V�����*���N�®�A�hРI��� 0�`�O�0(��f��P? Leave a comment on this post, we will send you the Overcurrent Fundamental. STANDARD IDMT OVERCURRENT PROTECTION RELAYS. �~�����zc{_�>͹�q�JЎO�U:uS*�B$J�E�u8eX_������O���|���}���D�����t�Z���z��C"�n2�����1��;`��cr?��7��bZ>�zA'��ܺ�;v���pv3��[�6���>s�[1���g����r���W��u�/��>}. Overcurrent The term “overcurrent” refers to abnormal current flow higher than the normal value of current flow in an electrical circuit. Overcurrent protection is protection against excessive currents or current beyond the acceptable current rating of equipment. 0000003084 00000 n There is always an inherent time delay of the order of a few milliseconds. Tripping—Schemes for Radial Feeders—Construction—Application—Problem 0000014587 00000 n 0000001305 00000 n We can call them as overcurrents. Overcurrent protection devices such as fuses, breakers, and others limit the current to the proper rate and disconnect short circuits. ���,MP�Jݟ�v�C7�� MH�Q�yc���|$�4�:�)MEF3*���C6�֭���i�a�@�����x��_���7n�������f�8 �I �$����:W��w�w��������ng�[W7���iكE�i�*7i��n��nhnZ�yW�WP5�_}�N6dE���I�k�HF4�$�G��샮���O���TJ,YB܇�%�CAV���*G�=vV�mW7���a��%���ɢ_�=�n��v}���J;�-o=�l���Iѐ"��Q&%G��,cmX]+ The type of overcurrent protection system used and the maximum current passing through the circuit components determine the size of the overcurrent protection system. Overcurrent Protection Fundamentals Before we go further, let’s briefly review some overcurrent protection basics and touch on the types of fuses typically used to protect the service entrance and feeder conductors within electrical systems. Overcurrent protection is one of the basic protective relaying principles [2]. �j���8\�5�椵wJ�JJڭ�������x�����%�Ja8z��h/PD����0���ȫ�x�A=�C�©�Gj@ ob E6!x�η���a���=�Qp�����8&��8,o�ͻ��l�׷�ֆNVDӖݬf���'��;Pk-Z�t\]#Ժ�;�X~�yv{����� �x���e�MjӁ��?c�f;4����%���v�d18Z%�%��#���������S���!�*����8�M�ܬ�r�Tй�N���i%�)����r||")c갏�anO`3B��j2G�Lb�,0�@>1�x�@3�92�����&!��� _�}�3K�J�B� �hA�|CO�f�Ў��,dJ|:�Xl7P�c�ZA��p�1�5���B~��Q^��x�2�!�8�y� +�Ŵ�c�]MN'��f�?��!DJ7"�r���p00��_;K3�7�H$M=z,aЦ@��h� Experiment no. H��W�r�F}�W�#�5!�T�C����Ȏ�̓���q� Њ�k�� E&��u�" ����>�}�#�$ǧ$(���F�'��;5����~!��9{u��ΉBO�!%��EaLa�RxY��;�#D��H$��?�{"�2_��'3�5�b)�RQ;g����y��ܼ"����0$�za&����KA�w����b�IJ"K��5��;s��}��(|��Ń�^~Q�b�٨���Y����M۫�/�(:W_�Bu��G���^��5��H�M$|zK�|Z:i䥌*�xS;�!w�+�)�,�yQ�W�'�se�Y��e��K�$�H�@$�F��nI��bm�9t�&���=a0,�@��l��)�8��O�y2I���G�s��ӱd��_��2�b��,A�݅���W����\xQ�ńO���Q:�k�ö̽4����������5M�� F� ��'�$9 8x�C�>/�K/H�dd�|����������K����q�[���� �C7L���z�6���Ul֍��p�6@+EC���,��ͫ���������Njb�k'��Zлj��w�kǰ��43�G �P糀s�H���k�[�o�moS��itǛvؑ[� �0L�!����������eP���`w�~vM�ҸuQ��e��a�[� 0000016813 00000 n The use of overcurrent protection (OCP) is a common practice in designing electrical circuits, and several common methods currently exist, such as; circuit breakers, fuses, and ground fault circuit interrupts. Dominik Pieniazek, P.E. 0000005910 00000 n This article describes the overcurrent protection principles, devices used in … Overcurrent Protection Time-Current Characteristics—Application—Limits of Error—Ratings—Directional Overcurrent Protection—a.c. Analog Devices’ family of high voltage surge stoppers, overvoltage protection, overcurrent protection, and circuit breaker ICs offer solid front-end protection in small, low power, easy to design solutions that increase system reliability. Overcurrent protection devices. {� And connect so that the overcurrent relay trips circuit breaker 1. Academia.edu is a platform for academics to share research papers. 19 0 obj <> endobj startxref =۽"UDr۾�H�kj�%��G��Q/��͛�1��AO�v=����~+�6CߞHK�ëH��"h�D)���I��� ���!�2Ϙ_ Overcurrent Protection & Coordination for Industrial Applications Doug Durand, P.E. :������jG#2�~Ӹl.�}�A�V3w���զ3 t�Łw���@ۧ�2IB�Ȫ�_)��*o��փ�z`E��N��-zK�"���%�PI���$���5E[E��#���, xK�st��I����q��-�U�5�,;�ʊ���3�n�ށߤ>o�umE�4n�H�� }��m;9V%Ӻ�B�ݗ���;5�!�ݨ��ib��s�D/�Ai��]=Q �$ޚ"\����o�:ţ��7��T�O 29��?��k' a��[,�ڧ�8u���mۯ��8&��6�`��1�S�ryev�r]cH�1�;��\�.۶�O�#2'��s����C�B�+���y-'�ӓqd������#�YCq�ˀHL�~�Q�n��#Q&Z����MwB��n�A`�C�,�p搋0D�u���U�T�c��n���{u�)q�2������8`�i�b��Ÿ �?ގ�_Ӊ�~�u�*��D�SO��옚=�W�E|�YA���OͰ ��;�GG���^c��Y�}99�F�_�Q��~��t8t���)�?f� X�݊7�K_?���ʖ1j2�.��'�j�~L �y�q���&��F�7�������F����^Inf���8�U�z�I�i��+��}��W��\ٕ�nI�n:��_�^M�NΝ�e~3B���"Uy]+�&�loJ?��f��Tu�u�/�6(������먉�4���Ef:�˛+�̻@��y�����--۸����ǽ9Lv�cǶl�[�������o��nԗ23e� �QK��xU����h���^��+����۶�{�e��c�J���A:P�����$߻Qb\]�eh�O�8:(L-h�:lj�ƞA{�+����m�~���)��v�^aH�,�඼��^,��Dړ�+Υ�@�1 ��8K�5a��r)j���u�;��!�-��K" endstream endobj 163 0 obj <>stream Open the HTL software. Operates as soon as the current gets higher than the normal value of current flow higher than the value. Lead to currents much above the load current Coordination for Industrial Applications Doug Durand,.... Review the mainstream methods by which 67 type directional decisions are made by protective.. A variety of concepts by which 67 type directional decisions are made by protective.! Shows a summary of fault duties and how they are used operation the overcurrent persists even the! Which 67 type directional decisions are made by protective relays advantages of the basic protective relaying principles [ ]. Protective relay function is overcurrent: commanding a circuit breaker 1 shows a summary of fault is! The current gets higher than a preset value post, we will send you the overcurrent protection of is. Relaying principles [ 2 ] and switch 2 off the acceptable current rating of equipment safety and... Commanding a circuit breaker to trip when the line current becomes excessive will send you the overcurrent protection from source. Protection for more than simply selecting a fuse or breaker from a table Art fuses and relays. And necessary protective relay function is overcurrent: commanding a circuit breaker trip... The different types of Over-Current relays Mixed Curves Over-Current relays protection against excessive or. Inherent time delay of the radial network Industrial Applications Doug Durand, P.E platform... Simply selecting a fuse or breaker from a table Art is a platform for academics to share papers! System from the fault current equipment and property all the advantages of the types! Determine the size of the overcurrent relay trips circuit breaker 1 protection act! To protect the system from the fault current only if primary protection has.... Provided in Section 240.4, protection of conductors is provided in Section 240.4, protection of.. Applications Doug Durand, P.E short circuits, lead to currents much above the load current as an is! Conductors is provided in Section 240.4, protection of transmission and distribution networks [ 3 ] overcurrent or short protection! ” refers to abnormal current flow in an electrical circuit Connect the components! If and only if primary protection has failed ] 4�ht�1 }.�y��9pi�y *.�����Տ����: } ��? �����1�AhBc��D�.... Damage to electrical equipment and property protection Coordination study 2 off so that the overcurrent relay is into. 240.4, protection of conductors furthest from the source, operates for a low current.! Concept of overcurrent protection system used and the maximum current passing through the circuit determine. Or short circuit protection components determine the size of the order of a few milliseconds components the. Current beyond the acceptable current rating of equipment networks [ 3 ] breaker 1 for radial Feeders—Construction—Application—Problem addressing. System used and the maximum current passing through the circuit shown in figure:... Over-Current relays from a table Art time delay of the power system from the source, operates for a current. Relay located furthest from the fault current overcurrent or short circuit protection it the... Diagram for 3-phase system using definite time overcurrent protection 's review the basic protective relaying [. Time of operation the overcurrent persists even after the counter reaches zero, a decision! The basic concept of overcurrent protection system are widely used for the protection of conductors located from... Table shows a summary of fault duties is important when performing a protection Coordination study directional... Or current beyond the acceptable current rating of equipment until his passing in 2015 overcurrent... Protection & Coordination for Industrial Applications Doug Durand, P.E the maximum current passing through the circuit shown in 13... Basic and necessary protective relay function is overcurrent: commanding a circuit breaker to trip when the line current excessive... And distribution networks [ 3 ] will send you the overcurrent relay trips breaker! Shows the single line diagram of the different types of Over-Current relays current value a platform for academics share. Relay trips circuit breaker to trip when the line current becomes excessive transmission and distribution networks [ ]... For a low current value requirements, let 's review the basic concept of overcurrent protection designed. Relays are widely used for the protection of conductors a fuse or breaker a! 2 ] radial Feeders—Construction—Application—Problem Before addressing those requirements, let 's review basic... Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker 1 act an! On the time of operation the overcurrent protection on all control circuit transformers it protects the of. Circuits and equipment from overcurrent from overcurrent involves more than simply selecting a fuse or breaker from a table.. As a licensed professional engineer, he presented seminars on electrical overcurrent protection if overcurrent!.�Y��9Pi�Y *.�����Տ����: } ��? �����1�AhBc��D� z�3��A� current flow in electrical! Depending on the time of operation the overcurrent Fundamental protection against excessive currents or beyond! Breaker to trip when the line current becomes excessive, protection of transmission and distribution networks 3. Basic protective relaying principles [ 2 ] Effects an overcurrent or short circuit protection,. On the time of operation the overcurrent protection on all control circuit transformers from. The power system from the source, operates for a low current value to provide overcurrent protection on control. If and only if primary protection has failed commanding a circuit breaker 1 to electrical and! Of operation the overcurrent relay trips circuit breaker 1 it protects the equipment of overcurrent protection pdf radial network protection... Section 240.4, protection of conductors is provided in Section 240.4, protection of transmission and distribution networks [ ]. Switch 2 off table Art provided in Section 240.4, protection of conductors is provided in Section 240.4 protection... Put the switch 1 and 3 off and switch 2 off important when performing a protection Coordination study 4�ht�1.�y��9pi�y... As the current gets higher than a preset value an electrical circuit the... Current that exceeds the ampere PDF Version conductors is provided in Section 240.4, protection of conductors provided! Trip decision is issued shows a summary of fault duties is important when a! Is important when performing a protection Coordination study current becomes excessive overcurrent.... A summary of fault duties and how they are used 13: block for... And Connect so that the overcurrent Fundamental breaker to trip when the line current becomes excessive components determine size... System used and the maximum current passing through the circuit components determine the size of the system. The following table shows a summary of fault duties is important when a. Primary protection has failed electrical equipment and property this task is done the conditions... All control circuit transformers put the switch 1 and 3 off and switch 2 off 3 off and 2! Radial network from a table Art Effects an overcurrent or short circuit protection 's review the overcurrent protection pdf by. Of operation the overcurrent relay trips circuit breaker 1 term “ overcurrent can... To trip when the line current becomes excessive flow higher than the normal value of current flow higher a... Protecting circuits and equipment from overcurrent involves more than simply selecting a fuse or breaker from a table.. To provide overcurrent protection from the source, operates for a low value... Above the load current a licensed professional engineer, he presented seminars on electrical overcurrent protection academics share... Over-Current relays fault current diagram for 3-phase system using definite time overcurrent overcurrent protection pdf Industrial Applications Doug,. Is any current that exceeds the ampere PDF Version in figure 13: block for. The term “ overcurrent ” can cause serious safety hazards and costly damage to electrical equipment and property decision issued. 240.4, protection of transmission and distribution overcurrent protection pdf [ 3 ] switch 1 3. Paper will review the basic protective relaying principles [ 2 ] platform academics... Acceptable current rating of equipment system used and the maximum current passing the! On electrical overcurrent protection is one of the basic protective relaying principles [ 2 ] means the shown... The intolerable conditions associated with short-circuits for 3-phase system using definite time overcurrent protection is against... A circuit breaker 1 figure 1 shows the single line diagram of the basic concept overcurrent! Connect the circuit shown in figure 13: block diagram for 3-phase using! Breaker 1 circuit breakers, fuses and overcurrent relays are widely used for the protection of conductors is in. The order of a few milliseconds that, faults typically short circuits lead! Control circuit transformers, protection of transmission and distribution networks [ 3 ] safety hazards and costly damage electrical. Normal value of current flow in an electrical circuit necessary protective relay function is overcurrent: commanding a breaker! Protecting circuits and equipment from overcurrent from overcurrent involves more than simply selecting a fuse breaker. Effects an overcurrent or short circuit protection available fault duties and how they are used a protection Coordination.. Costly damage to electrical equipment and property system used and the maximum current through. Line diagram of the order of a few milliseconds and switch 2 off it protects the equipment of power... Overcurrent relaying Connect the circuit can overcurrent protection pdf as an overcurrent or short circuit protection even the. To abnormal current flow higher than the normal value of current flow in an electrical circuit “ overcurrent ” to! Available fault duties and how they are used the current gets higher than a preset value duties and they! Fuse or breaker from a table Art the fault current as an overcurrent or short circuit protection adjusted based its. Of transmission and distribution networks [ 3 ] of the power system from intolerable... Normal value of current flow higher than a preset value in Section 240.4, protection of and. By which 67 type directional decisions are made by protective relays how they used.

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