Power System Studies

Protection Coordination Study

Selective tripping, relay grading, and TCC curve optimisation.

Every fault cleared at the closest upstream device. Nothing more. Time-current characteristic curves graded to IEEE 242 (Buff Book), relay settings delivered ready to load, coordination margins verified by simulation. The smallest possible outage on the worst day.

Why this matters

Why mis-coordination costs more than a fault

A bus fault should trip a feeder breaker · not the main incomer that takes the whole plant offline. Mis-coordination is the difference between a 20-minute outage on one feeder and a 6-hour outage that takes the entire plant black. Plants that have grown over decades almost always have inherited mis-coordination · new feeders added without re-grading, relay settings copied from the previous plant, time-overcurrent characteristics overlapping. A protection coordination study isolates these, optimises settings to IEEE 242 grading margins, and delivers settings ready for your protection team to load.

Method

How we deliver Protection Coordination Study

CEng MIE India-signed deliverables · LiDAR-powered where applicable · digital twin handover ready · routes to the Power System Studies practice lead within 24 hours.

Protection device inventory

Every relay, fuse, MCCB, and breaker captured · make, model, current settings, firmware version. Existing TCC curves digitised.

Coordination simulation

ETAP or DigSILENT Star/StarZ module used to plot TCC curves and verify coordination margins at every fault location.

Optimisation

Settings re-graded to IEEE 242 margins (0.3-0.4 sec between adjacent devices). Instantaneous pickup thresholds optimised against the short-circuit study output.

Selectivity verification

Every fault scenario from the short-circuit study cross-checked against the proposed settings. Mis-coordination flagged and resolved iteratively.

Settings sheets + sign-off

Per-relay settings sheets delivered in CSV + PDF. Compatible with SEL, ABB REF/RET, Siemens 7SJ/7SA, GE Multilin loading. Report CEng MIE-signed.

Standards + compliance

Built to the standards your auditors quote

Reports reference the international and national standards your regulators, F500 audit teams, and corporate process safety leads cite. Every deliverable signed by a Chartered Engineer (CEng MIE India).

IEEE 242 (Buff Book) · Protection and Coordination of Industrial and Commercial Power Systems
IEC 60255 series · Measuring relays and protection equipment
IEEE C37.112 · Inverse-Time Characteristic Equations for Overcurrent Relays
API RP 540 · Electrical Installations in Petroleum Processing Plants
IS 14697 (India), AS 1768 (Australia) · protection coordination national codes

Anonymous case anchors

What this looks like in production

Three landmark engagements from our verified roster · quantified outcomes, no client names disclosed without written permission.

Refinery, India · 89 relays re-graded

Inherited mis-coordination from 3 phases of plant expansion. Re-graded 89 relays. Reduced incomer trip events from 14/year to 0 in the next operating year.

Pharma site, Singapore · GMP audit

GMP audit flagged inadequate protection documentation. Delivered settings sheets + coordination report + TCC curves. Audit closed in 4 weeks.

Mine, Australia · MV underground

AS 1768 grading for underground MV distribution. Re-graded for new battery-electric haul fleet load profile.

Frequently asked

Protection Coordination Study · the practical questions

Do you load the settings, or just deliver the sheets?

We deliver settings sheets ready to load. Loading is typically done by your protection team or the relay OEM service engineer. We can be on-site to supervise loading + commissioning testing for an additional scope.

My relays are a mix of SEL, ABB, Siemens, GE. Can you handle all of them?

Yes. The coordination simulation is platform-agnostic (ETAP Star/StarZ). Settings sheets are output per relay make/model in the format that vendor's setting software accepts.

How does this interact with your protection upgrade recommendations?

If the coordination study finds your existing relays cannot achieve the required grading margins (often the case with 30+ year old electromechanical relays), we recommend a numerical relay retrofit. The relay shortlist and SOR (Statement of Requirements) is part of the deliverable.

Do you do trip testing as well?

Yes · primary and secondary injection testing via our field services partners. Quoted as a separate phase. Most clients do trip testing 1-2 weeks after settings loading.

Can you coordinate generator protection alongside grid protection?

Yes. Generator differential, stator earth fault, loss of field, reverse power · all graded against the upstream and downstream device characteristics. Critical for captive power plants and process-driven cogen.

Scope your Protection Coordination Study engagement.

Tell us your plant, region, and scope · a named Chartered Engineer responds within 24 hours.

4 fields. No phone interview to start.
Per-discipline routing to the Power System Studies practice lead.
Anonymous case anchors sent with first reply.
Same-day callback for deadline-driven enquiries.

Power System Study Scoping

ETAP/DigSILENT/PSCAD-led · routes to Practice Lead PSS · 24-hour response.