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Carelabs

IEEE 1584 · Engineering

Optimize Fault Response With Relay Coordination Study

Avoid unnecessary outages and protect the system with a reliable relay coordination study report from Care Labs, Singapore. Carelabs builds the study from your facility's one-line diagram, modeling every relay and breaker in ETAP to confirm each device trips only for the fault nearest to it.

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Grading when there is no outage window

On a building or facility that runs continuously, protection is rarely tested and settings are rarely revisited. The work has to be structured around that constraint rather than assuming a shutdown that will never be granted.

What We Deliver

As-found audit without interruption

Settings are read from relays and trip units, and CT ratios and wiring verified, with the installation running. This establishes the real baseline before any change is contemplated.

THE CONSTRAINT

Never tested, never revisited

Continuous operation means protection settings applied at commissioning may never have been examined since. The installation has been extended, fault levels have moved, and the scheme has quietly stopped being selective.

  • Settings read out of the devices rather than transcribed from the schedule, since the two routinely disagree after years of undocumented adjustment.
  • Grading checked against calculated fault levels at each position rather than against the generic curves supplied with the device.
  • CT ratio, class and burden verified, because a saturating CT feeds distorted current and the relay then operates correctly on wrong information.
  • Changes classified by the access they need, so a programme can proceed through short windows instead of waiting for a shutdown that never comes.
  • Every recommendation reported with its arc flash consequence, as faster clearing lowers incident energy and longer grading margins raise it.
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DELIVERABLES

What you receive

Issued against SS 638 and signed by the engineer who carried out the grading.

  1. 1As-found settings register covering every relay and adjustable trip unit
  2. 2Time-current curves per grading path with the achieved margin annotated
  3. 3Discrimination register naming each failing pair and the fault range where it fails
  4. 4Recommended settings grouped by the access required to apply them
  5. 5A verification checklist so applied values can be proven against the approved schedule
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How the study runs

01

Audit live

Every relay and trip unit is interrogated with the installation running, and as-found values recorded together with CT details and protection wiring.

02

Confirm the fault basis

Grading depends on fault current at each device position, so a verified short circuit basis is established from an existing study or within this scope.

03

Model the devices

Manufacturer characteristics are built for every installed device, including intentional delays configured into electronic trip units.

04

Test discrimination

Each pair is checked across the full fault range, and any band where selectivity is lost is recorded with the currents that produce it.

05

Stage the changes

Recommendations are grouped by required access, so the programme can be executed against the windows the site can realistically provide.

06

Apply and verify

Settings are applied in stages with a verification checklist, so the position is provable at every point rather than only at the end.

Frequently asked questions

Most of it, yes. Reading settings, verifying CTs and the entire analysis are carried out with the plant running. Only applying settings to devices that cannot be changed live, and any injection testing, require isolation. Grouping recommendations by required access lets the work proceed through short windows rather than one shutdown.
Through a verification checklist issued with the settings. Where changes are applied across several short windows by different people, the risk is not the calculation but the transcription. A checklist that confirms each applied value against the approved schedule is what makes the final position provable.
It is usually the reason the study is needed. Each extension changes fault levels, and settings calculated for the original installation stop being selective for the network you now operate. The extensions are individually sound; the cumulative effect on discrimination is what goes unexamined.
Faster clearing reduces incident energy, which is the favourable direction. The tension runs the other way: buying selectivity by delaying an upstream device raises the energy a worker faces at that position. Every recommendation is reported with its energy consequence so the trade-off is made openly.

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