Return-Path: Delivered-To: shishir@banglamarkgroup.com Received: from server2.www.flokoin.com by server2.www.flokoin.com with LMTP id 2HgrMy6NFGk/IyQAB2Lfrw (envelope-from ) for ; Wed, 12 Nov 2025 13:35:42 +0000 Return-path: Envelope-to: shishir@banglamarkgroup.com Delivery-date: Wed, 12 Nov 2025 13:35:42 +0000 Received: from o1678952x239.outbound-mail.sendgrid.net ([167.89.52.239]:32590) by server2.www.flokoin.com with esmtps (TLS1.3) tls TLS_AES_128_GCM_SHA256 (Exim 4.98.2) (envelope-from ) id 1vJB0h-00000009wGS-2WmN for shishir@banglamarkgroup.com; Wed, 12 Nov 2025 13:35:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=newzenler.com; h=list-unsubscribe:list-unsubscribe-post:list-id:from:subject: content-transfer-encoding:date:mime-version:reply-to:to:content-type:cc:content-type:date:from: subject:to; s=s1; bh=R7DPaKeJov1ws9eBCQ6zcIZ3k1cqcv9mYGe+Hnak+9Q=; b=PQIjIYGuFcIPbaNFHOgdjj71t6REWrLThxIMfCF16hwBenWRs79/kijI1n0Qf7XKbsQe /NddqI8NIX+fNb8nCXexkjbDHZgUo00N9cwJf6azl4Mw/+547mbZRhYcWa2bVEDwM8yxal pjzdiJFvaOKyUQyTWvNsAX6S2sYhqKx9OYUfPNMRPAMQiLuvXjdmxWwStCDe/tNsVt5FmZ Qd6CJqh2MIfZoMlwmINCAm7lLKOrFcS4LHPfoQJtzMLmmEQE9MQkCbvZheF2OLcesokFsb GKbaeIXF90LrVe8AngQ5xzVvbS6SMz/ZaOgho61ApOPOJ6xnMnbjfn6zzqpGFpHA== Received: by recvd-6fc848bf8d-bgpkq with SMTP id recvd-6fc848bf8d-bgpkq-1-69148D02-4D 2025-11-12 13:34:58.836156455 +0000 UTC m=+13899056.850569744 Received: from ip-10-116-6-46.ec2.internal (unknown) by geopod-ismtpd-2 (SG) with ESMTP id HNFNLfsvRGaeWbJs8069cQ for ; Wed, 12 Nov 2025 13:34:58.769 +0000 (UTC) List-Unsubscribe: =?us-ascii?Q?=3Chttps=3A=2F=2Fwww=2Epowerprojectstraining=2Ecom=2Fmail=2Funsubscribe=2FeyJhbG?= =?us-ascii?Q?ciOiJIUzI1NiIsInR5cCI6IkpXVCJ9=2EeyJ1c2Vy?= =?us-ascii?Q?X2lkIjoiMTMxMDcuNjdkNGZiNTNiMWQ3YyIsImV?= =?us-ascii?Q?tYWlsX3NlbmRfaWQiOiI2OGU1ODRkMTMzODI0ZD?= =?us-ascii?Q?liOWIwMzFhZjIiLCJjYXRlZ29yeSI6MSwiY2F0Z?= =?us-ascii?Q?WdvcnlfaWQiOiIiLCJzY2hvb2xfdXJsIjoiaHR0?= =?us-ascii?Q?cHM6Ly93d3cucG93ZXJwcm9qZWN0c3RyYWluaW5?= =?us-ascii?Q?nLmNvbSIsInNjaG9vbF9pZCI6MTMxMDcsImlhdC?= =?us-ascii?Q?I6MTc2Mjk1NDQ5OH0=2EvkHG-npHekte6xveEgP6w?= =?us-ascii?Q?yXsCLsLyBWGEumMihugilI=3E=2C?= List-Unsubscribe-Post: List-Unsubscribe=One-Click List-ID: the 'https://www.powerprojectstraining.com' via Email Broadcasting From: Selvakumar Subject: Do you always need 67/67N on incomers? Not really. Message-ID: <3d746686-7bff-7acf-f510-4f2d42d5f0ac@powerprojectsindia.com> Content-Transfer-Encoding: quoted-printable Date: Wed, 12 Nov 2025 13:34:58 +0000 (UTC) MIME-Version: 1.0 Reply-To: selvakumar@powerprojectsindia.com X-SG-EID: =?us-ascii?Q?u001=2EcKjL+JRDAQ6syzs3DUgW7jzKWwJ7mAeyrSA21MGpnu6x6pVoBTwfoYzm0?= =?us-ascii?Q?79yZnSzo58o8hou7BLMnruxQNe0zgx0gP=2FSEJST?= =?us-ascii?Q?JUOK2TCEv+16byafNwHRho6GFMwzTrHbDf8uDvL?= =?us-ascii?Q?+rZRqGWXsu=2F5DTX00AeqiY=2FBSJUqZVR0gJ1nX5A?= =?us-ascii?Q?2SEUyposC74DMOrAvAlsVcm7ddRuoUi29dHijaX?= =?us-ascii?Q?GuMW3ZQ5Nsd9GCm7I0m1O=2FylhAAJkq1fuwVN8JZ?= =?us-ascii?Q?B26y0EyY72SlKaqbYLec8dBwIQ=3D=3D?= To: shishir@banglamarkgroup.com X-Entity-ID: u001.sv/2PJNoaDOr/V28MEjImg== Content-Type: text/html; charset=utf-8 X-Spam-Status: No, score=1.9 X-Spam-Score: 19 X-Spam-Bar: + X-Ham-Report: =?ISO-8859-1?Q?Spam_detection_software=2C_running_on_the_system_=22server2=2Ewww=2Ef?= =?ISO-8859-1?Q?lokoin=2Ecom=22=2C=0A_has_NOT_identified_this_incomin?= =?ISO-8859-1?Q?g_email_as_spam=2E__The_original=0A_message_has_been_?= =?ISO-8859-1?Q?attached_to_this_so_you_can_view_it_or_label=0A_simil?= =?ISO-8859-1?Q?ar_future_email=2E__If_you_have_any_questions=2C_see=0A_?= =?ISO-8859-1?Q?root=5C=40localhost_for_details=2E=0A_Content_preview?= =?ISO-8859-1?Q?=3A__Text_Engineers_often_apply_67/67N_=28directional?= =?ISO-8859-1?Q?_protection=29=0A____on_every_incomer_as_a_default=2E_?= =?ISO-8859-1?Q?=0A_Content_analysis_details=3A___=281=2E9_points=2C_?= =?ISO-8859-1?Q?5=2E0_required=29=0A__pts_rule_name______________desc?= =?ISO-8859-1?Q?ription=0A_----_----------------------_--------------?= =?ISO-8859-1?Q?------------------------------------=0A__1=2E2_RCVD=5FI?= =?ISO-8859-1?Q?N=5FBL=5FSPAMCOP=5FNET_RBL=3A_Received_via_a_relay_in?= =?ISO-8859-1?Q?_bl=2Espamc X-Spam-Flag: NO Text

= Engineers often apply 67/67N (directional protection) on every incom= er as a default.

But do you always need it? Not really.

 
 

Think of a simple 11 kV double-incomer system with a bus co= upler.

=F0= =9F=94=85 If all three breakers (two incomers + bus coupler) remain = closed in normal operation, then faults can feed from either side. = Current may reverse, so incomer relays need directional elements = (67/67N) to distinguish forward vs reverse.
=F0=9F=94=85 But = if you follow a two-out-of-three scheme=E2=80=94where the bus c= oupler is normally open, and each incomer feeds its own section=E2=80=94the= n current never reverses. In that case, non-directional 50/51, 50N/= 51N are enough. Directional adds cost and complexity without benef= it.

This is = why system configuration matters as much as fault levels in relay se= lection. Directional protection is not =E2=80=9Calways required=E2=80=9D=E2= =80=94it=E2=80=99s conditional.

= <= /table>
 
 

Here=E2=80= =99s a quick mental checklist:

=E2=9C=85 Parallel incomers with bus coupler= normally closed? =E2=86=92 Yes, enable 67/67N.
=E2=9C=85 Two inc= omers split, bus coupler normally open? =E2=86=92 No, standard 50/51, 5= 0N/51N suffice.
=E2=9C=85 Ring bus, parallel sources, or export capa= bility? =E2=86=92 Yes, always directional.

Too often, designs enable directional on every in= comer =E2=80=9Cjust to be safe.=E2=80=9D The result? Extra CTs, wiring, log= ic, and coordination headaches. And if your operators run the system in two= -out-of-three mode, those settings are never exercised.

 
 
 
<= p style=3D"padding: 0px; margin: 0px 0px 20px; font-family: 'IBM Plex Sans'= ; color: #222228; font-size: 16px; line-height: 24px;">Relay settings must = match the operating philosophy, not just the one-line diagram.
What=E2=80=99s your biggest challenge with directional p= rotection?
 
3D"LinkedIn"  <= img border=3D"0" width=3D"30px" alt=3D"Instagram" src=3D"https://s3.us-east= -1.amazonaws.com/contents.newzenler.com/13107/library/Instagram - Black67dc= 04ce8cfaf_lg.png" style=3D"margin: 0px; padding: 0px; max-width: 100%; bord= er: none; vertical-align: top; width: 30px;">  = ;3D"YouTube"
<= tr>

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