Protection Coordination Time Calculator

Audit independently established same-fault protection operating-time pairs and caller margins, no relay settings or verified selectivity. Caller independently establishes units, regime, calibration and applicability; this does not establish design-code compliance, authenticity, operational safety, treatment efficacy or a validated forecast.

Description

Protection coordination compares upstream and downstream operating times with a chosen margin.

Protection coordination compares upstream and downstream operating times with a chosen margin.^[1]

The supplied times need a common fault condition before their reserve is meaningful. Use this tool to calculate protection Coordination Time from the supplied measurements and assumptions.

When to use Protection Coordination Time Calculator

Use this tool to calculate protection Coordination Time from the supplied measurements and assumptions. Establish the SI units or caller unit basis, load signs, measurement interval, model conditions and independently chosen coefficients or references.

How to use Protection Coordination Time Calculator and understand its results

Establish the SI units or caller unit basis, load signs, measurement interval, model conditions and independently chosen coefficients or references.
Enter callerDownstreamOperatingTimesSeconds, callerUpstreamOperatingTimesSeconds, callerVerifiedCoordinationMarginsSeconds, using the field meanings and rules below, then run the tool.
Read signedCoordinationReserveSeconds, knownCoordinationReviewIndices. Interpret the fields using their units, signs and evidence conventions below.
If input validation fails, correct the reported field and run again. Before applying the result, check reference scope, model assumptions and any missing evidence or placeholder values.

Input field	Meaning	Value type	Requirement
callerDownstreamOperatingTimesSeconds	Caller downstream operating times seconds	list of number	Required
callerUpstreamOperatingTimesSeconds	Caller upstream operating times seconds	list of number	Required
callerVerifiedCoordinationMarginsSeconds	Caller verified coordination margins seconds; caller assertion or measurement requiring independent evidence	list of number	Required

Enter nonempty aligned nonnegative upstream/downstream operating times and margins in seconds. Return upstream−downstream−margin and zero-based indices with negative reserve. Equality is not flagged; no time-current curves or fault-current selectivity are computed.

reserveSeconds_i=upstream_i−downstream_i−margin_i; review={i:reserve_i<0}

Use the exact units, boundary rules, ordering and missing-evidence conventions above.

Output field	Meaning	Value type
signedCoordinationReserveSeconds	Signed Coordination Reserve Seconds; follow the units, sign, ordering and evidence convention stated above	list of number
knownCoordinationReviewIndices	Known Coordination Review Indices; follow the units, sign, ordering and evidence convention stated above	list of number

json

{
  "input": {
    "callerDownstreamOperatingTimesSeconds": [
      0.1,
      0.2
    ],
    "callerUpstreamOperatingTimesSeconds": [
      0.3,
      0.25
    ],
    "callerVerifiedCoordinationMarginsSeconds": [
      0.1,
      0.1
    ]
  },
  "output": {
    "signedCoordinationReserveSeconds": [
      0.09999999999999998,
      -0.05000000000000002
    ],
    "knownCoordinationReviewIndices": [
      1
    ]
  }
}

Limitations and assumptions

The supplied times need a common fault condition before their reserve is meaningful. Interpretation depends on the units, sampling scope and exact model described above.

All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse evidence arrays fail validation; the specific bounds and alignment requirements are stated above. Extremely large inputs or outputs can also be rejected. An input error is distinct from a successful result reporting false, no matches or missing evidence.

Alternative or Complementary methods

Use Fuse Rating Selector for this related task: Fuse selection needs both continuous-current capacity and interrupting capacity for the declared fault.

Use Motor Starting Voltage Drop Calculator when its separate inputs and assumptions fit the question: A balanced motor-current approximation combines circuit resistance, reactance and power factor.

References

Protection Coordination Time Calculator — tool.io

Similar or alternative tools

Fuse Rating Selector
Fuse selection needs both continuous-current capacity and interrupting capacity for the declared fault.
Motor Starting Voltage Drop Calculator
A balanced motor-current approximation combines circuit resistance, reactance and power factor.