What ELAP computes, under which standard, and where it stops

StandardEngineering criterionE7

Cumulative voltage drop per tier (DC / LV / MV) up to the point of interconnection. It sums ΔV% within each tier and never across tiers: a percentage at 1500 Vdc is not additive with one at 33 kV.

StandardEngineering criterionE9

Total losses and losses per voltage tier, and what percentage of delivered energy they represent.

StandardEngineering criterionE4

Per-feeder capacity (loading% · √3 · kV · ampacity) and grouping of block-transformer stations into a capacity-bounded nearest-neighbour chain from the collector.

StandardEngineering criterionP2

Voltage and angle per bus, flow and loss per branch. The solver picks the method by topology: radial backward-forward sweep on a tree (exact, not an approximation) or a nodal Ybus solve when rings are present.

StandardEngineering criterionP2

Switches out each transformer and each AC cable one at a time, and ranks the thermal, voltage and withstand violations that appear.

Where it stopsThe full N-1 stays in ETAP / PSS-E.

StandardIEEE 519IEC 61000-3-6P4

Current TDD and voltage THD at the point of common coupling against the limits in the standard.

Where it stopsThe harmonic study using the manufacturer's real spectrum is not included.

StandardIEEE 519P4

Nodal impedance |Z(h)| for h = 1…50; flags parallel resonance when it lands near a characteristic harmonic order.

Where it stopsThe harmonic penetration study with a manufacturer model stays in ETAP / PSCAD.

StandardIEC 60287P4

Ampacity of the buried cable, accounting for duct-bank grouping.

Where it stopsIt solves the reduced thermal chain (T1 + T4) and omits dielectric losses Wd and the sheath/armour factors λ1/λ2. Those omissions are NOT conservative: they raise the ampacity. The full T1…T4 calculation is detailed engineering.

StandardIEC 60909E16

Voltage retained at each bus during a three-phase fault at another: V = 1 − Z(i,k)/Z(k,k) over the impedance matrix.

Where it stopsFlat 1.00 pu prefault, positive sequence, and no credit for converter contribution. Full sequence analysis stays in ETAP / PSS-E.

StandardIEC 60909E6

Maximum and minimum Ik″ per bus from the Thévenin equivalent, plus the inverter backfeed contribution.

Where it stopsFull IEC 60909 stays in ETAP.

StandardIEC 60909P2

Ik″ and ip per bus to specify switchgear. The solver picks the method: radial accumulation on a tree, or sequence Zbus when rings are present.

Where it stopsThe radial method opens the rings and returns a LOWER BOUND. Full IEC 60909 stays in ETAP.

StandardIEC 60255-151IEEE C37.112P3

Coordination time interval (CTI) per series pair, instantaneous element (50) and transformer inrush, with 51 grading over the radial tree and auto-tuning.

Where it stopsThis is screening coordination, not certified: rigorous TCC/Star plotting, fine 50 grading and setting-grade 87/67/21 coordination are detailed engineering in ETAP.

StandardIEC 60255-151P3

Grades overcurrent in every radial configuration of the ring (base case plus each tie opened) and flags the pairs that reverse orientation, which require a directional element (67).

Where it stopsA non-directional overcurrent does not coordinate a closed ring. Directional coordination with the ring closed (Zbus sharing) stays in ETAP.

StandardIEEE C37.112IEEE C57.109P3

Checks that each proposed curve falls inside the damage / inrush / load / minimum-Ik / CTI corridor.

Where it stopsIt is a mechanical corridor check over screening-grade damage curves (transformer thermal, cable adiabatic). Certified Star plotting and rigorous damage curves stay in ETAP.

StandardIEEE 1584-2018P3

Incident energy and arc-flash boundary. It REFUSES to compute outside the standard's range (≤ 600 V per §4.10, and > 15 kV).

Where it stopsThe engine permanently flags its result as advisory and does NOT determine personal protective equipment. The cross-check against ETAP is still pending.

StandardIEEE 80E15

Grid resistance, ground potential rise (GPR), and step and touch voltages.

Where it stopsEm/Es grid design is detailed engineering.

StandardEngineering criterionE14

Grounding transformer and neutral earthing resistor (NGT / NER), earth-fault factor, and arrester continuous voltage (Uc) and temporary overvoltage (TOV).

Where it stopsThermal sizing of the NER/NGT — withstanding the fault current for the clearing time — is detailed engineering.

StandardIEC 60071P4

Arrester rated voltage (Ur) and MCOV, and the minimum standardised basic insulation level (BIL) derived from the earth-fault factor.

Where it stopsThe residual voltage (Upl) comes from an in-house representative ratio, not from the published Upl of the selected arrester. The resulting BIL is a proposal to verify against the datasheet, not a closed specification.

StandardIEC 62305P4

Strike density Nd from the collection area (full eq. A.2) and risk R1 against the tolerable risk, with the suggested protection class.

Where it stopsR1 is computed with the probability·loss product collapsed into a single constant. The R_A…R_Z components per zone, with their probabilities and losses — that is, IEC 62305-2 proper — are not implemented.

StandardIEC 62109-2UL 1741UL 1699BP4

Checks which functions the arrangement requires — insulation monitoring (IMD/RCMU), ground-fault detection and interruption (GFDI), arc-fault detection (AFCI) — and reports the missing ones, along with the first-fault current.

Where it stopsIt is a conformity screening — which functions are missing — not the design or the certification testing of the device.

StandardIEC 61660E12

Fault current on the DC bus as the sum of partial contributions: battery (dominant), current-limited converter, and the PV combiner Isc contribution. This is what rates the DC-side breakers, fuses and busbars.

Where it stopsThe time constants (t_p, τ) are a later refinement and the cross-check against ETAP's DC short-circuit module is deferred.

StandardIEEE 1547.1P5

Grid-code voltage, frequency and RoCoF windows against the scheme's 27 / 59 / 81 settings.

Where it stopsThe demonstration is made with the manufacturer's certified model.

StandardEngineering criterionE16

Checks that the interface protections (27 / 59) do not disconnect the plant inside the ride-through envelope during someone else's fault.

Where it stopsIt does NOT evaluate current elements. The demonstration requires a certified EMT/RMS model and the operator's case.

StandardEngineering criterionE16

Composes depth (impedance matrix), duration (clearing time, which is the operator's datum) and the code envelope: how much voltage is retained, whether it must be ridden through, and whether your own 27 / 59 would trip for someone else's fault.

Where it stopsIt requires a certified EMT/RMS model and the operator's case. If the clearing time is missing, the study declares it missing instead of assuming it.

StandardEngineering criterionP1

Coincident maximum demand of LV auxiliary services: applies each load's demand factor, sums active and reactive, applies plant diversity, and returns kVA and current.

StandardEngineering criterionP1

Picks the smallest standard kVA step that keeps loading at or below target, and reports normal loading, N-1 loading — the governing case is the surviving transformer carrying the full demand — and primary and secondary currents.

StandardEngineering criterionE10

P-Q envelope at the interconnection point against the agreement's target power factor. It subtracts the reactive power absorbed by the collector network, so the envelope sits at the interconnection point and not at the inverter terminals.

StandardEngineering criterionE13

Turns a power and duration target into nameplate energy, C-rate, converter apparent rating, charge energy, and end-of-life augmentation.

StandardIEEE 485P1

Max-section method sizing: cell capacity from the duty (continuous load × autonomy, plus the momentary breaker-operation load), with the Kt factor for discharge rate, aging, temperature and design margin; plus the charger and the autonomy hours.

Where it stopsIt uses a representative lead-acid Kt table: for the final design it must be verified against the published discharge curve of the selected cell.

StandardEngineering criterionE8

Voltage variation at the interconnection point when the plant connects or disconnects, against the connection agreement's band: ΔU/Un = (P + Q·k) / (Scc · √(1 + k²)), closed over the grid short-circuit power and its X/R ratio. The reactive setpoint sweep reports the worst case in both directions.

Where it stopsIt is not a load flow: it is the accepted distribution screening. Real fault level and dynamic behaviour stay in ETAP.

StandardIEC 61000-3-7P4

Planning short-term severity (Pst) at the point of common coupling against the level allocated by the network.

Where it stopsMeasurement with an IEC 61000-4-15 flickermeter is done in PSCAD.

StandardEngineering criterionP5

Overlays the grid code's mandatory envelope against the declared undervoltage and overvoltage trips, and checks the dynamic reactive-current K factor and the active-power recovery rate.

Where it stopsIt is the pre-compliance verdict a developer submits. The certified run with the manufacturer's EMT/RMS model stays in PSS-E / PSCAD. An undeclared manufacturer datum is reported as undeclared, never as zero.

StandardEngineering criterionP5

Reduced-order positive-sequence RMS simulation through a scripted voltage dip: dynamic reactive-current support ΔIq = K·ΔV outside the dead-band, current-priority limiting, and an active-power recovery ramp. It returns the V/P/Q/Iq(t) trajectory.

Where it stopsSingle machine equivalent, explicit fixed step, positive sequence and scripted voltage. The certified EMT/RMS run stays in PSCAD / PSS-E.