IEEE 1584 · Engineering

Protection Coordination Made Reliable

Give your power systems the right protection from cascading faults with an in-depth relay coordination study in Malaysia. Carelabs builds this from your facility's one-line diagram, modeling relays, breakers, and damage curves in ETAP to confirm the fault clears at the closest point rather than tripping equipment further upstream.

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What the study establishes

Coordination decides how much of your plant goes dark when a fault occurs, and how long the fault burns before it is cleared. Those two answers pull against each other.

What We Deliver

Grading across every protection path

Time-current curves are plotted for each path from final circuit to incomer, and the grading margin at every level is checked against relay operating time, breaker interrupting time and CT error rather than against habit.

WHY IT MATTERS

A fault on one feeder should not take the site

When a downstream fault trips the incomer instead of the local breaker, the cause is rarely a faulty device. It is grading set at commissioning and never revisited as the plant grew. Each extension changes fault levels; old settings stop being selective.

Grading verified against calculated fault levels at each point, not against the generic curves supplied with the relay.
Relay settings read from the device rather than transcribed from the settings schedule, because the two frequently disagree after years of commissioning adjustments.
CT ratio, class and burden checked; a saturating CT delivers a distorted current and the relay then operates correctly on the wrong information.
Coordination assessed on both utility supply and standby generation. The generator case is the one usually skipped, and decaying fault contribution can leave a downstream fault uncleared.
Miscoordinating pairs listed with the fault current range over which selectivity is lost, rather than reported as a simple pass or fail.

DELIVERABLES

What you receive

The package is issued against MS IEC 60364 and the protection requirements in the Electricity Regulations 1994, and is signed by the engineer who performed the grading.

1Time-current curves for every grading pair, plotted on log-log axes with the margin annotated
2Settings schedule per relay and adjustable trip unit, recording both as-found and recommended values
3Miscoordination register naming each overlapping pair and the fault range where selectivity is lost
4Separate earth fault grading with pick-up and time multiplier per device
5A statement of the arc flash consequence of each recommended change, so the safety trade-off is explicit

Reach Out

How the study runs

Protection audit on site

Settings are read directly from each relay and trip unit. CT ratios, polarity and burden are verified against the schematics rather than assumed to match them.

Fault level inputs

Grading depends on fault current at each device position, so a verified short circuit basis is established first — either from an existing study or as part of this scope.

Curve construction

Manufacturer characteristics are built into the model for every installed device, including any intentional delay configured in electronic trip units.

Grading calculation

Margins are calculated at each level with explicit allowances for relay operate time, breaker interrupting time and measurement error, instead of a single flat assumption.

Trade-off review

Where selectivity and clearing time conflict, options are presented with the arc flash consequence of each, and the decision is made with your engineering and safety teams rather than for them.

Settings issue and verification

Final settings are issued for application, with a re-verification checklist so the applied values can be proven against the approved schedule afterwards.

Frequently asked questions

A network can go years without a fault in the position that would expose bad grading. The absence of a mis-operation is evidence that you have not yet had the wrong fault in the wrong place, not evidence that grading is correct. The study establishes which of the two situations you are in.

Yes, and this is the trade-off that matters most. Selectivity is often bought by delaying the upstream device, which lengthens arcing duration and raises incident energy at that location. We report the energy consequence of every recommended change so the choice between selectivity and worker exposure is made openly.

Both arrangements are available. Where your own team applies the settings we issue them in the format the relays are configured in, plus a verification checklist. Where we apply them, as-found values are recorded first so the change is fully traceable if a later investigation needs it.

A generator's fault contribution decays within seconds, so the current available to operate a downstream device late in a fault can fall below its pick-up. Grading that is correct on the TNB supply may leave a fault uncleared on generator supply, which is why the two source cases are graded separately.

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