Electrical· Worked example · Release 2.69
Worked example — LV load schedule, cables and fault levels
A treatment-plant process building: four distribution boards, fourteen loads with their demand factors, a UPS, cables sized with derating and voltage drop, and fault levels at every board. The Electrical Design Bench carries the demand up the board tree, sizes each feeder and checks the protective devices; in ASH ELDAS the same project feeds the network studies.
The figures on this page are the bench's built-in example project with sample data ("Example — Treatment plant process building"), generated from the software itself, not a real project. Values the bench takes from a document in the ASH library carry the clause; values it assumes are labelled "engineering default" in the software.
What the example starts from.
| Location | Example site |
|---|---|
| Scope | Independent check of the LV load schedule, cable sizing and fault levels (sample data). |
| Distribution boards | 4 rows |
| Loads | 14 rows |
| UPS systems | 1 row |
| Rooms | 3 rows |
| Earthing systems | 2 rows |
| Life-safety loads | 7 rows |
| Arc-flash points | 3 rows |
| Library devices | 2 rows |
What comes out.
185 checks are evaluated in the detailed design stage; the rows below are the ones a reviewer looks at first (Code C, then B), each with the clause it rests on.
| Item | Check | Demand | Capacity / limit | Unit | Code | Clause |
|---|---|---|---|---|---|---|
| RAS-01 | Breaker ≥ 1.25 × FLC | 68.47 | 63 | A | C | IEC 60364-4-43 §433.1 |
| RAS-01 | Breaker In ≤ derated cable rating Iz | 63 | 52.20 | A | C | IEC 60364-4-43 §433.1 (Ib ≤ In ≤ Iz; In = the setting of an adjustable device) |
| UPS-1 | Battery capacity (C10) for 60 min | 43.88 | 40 | Ah | C | IEEE 485 (constant-power method with the capacity-rate factor Kt; ageing 1.25, design margin) |
| R3 | Average illuminance ≥ required | 300 | 244.44 | lux | C | EN 12464-1; lumen method |
| MX-01 | Earth-fault disconnection ≤ 0.4 s (Ik1 0.20 kA) | 2.13 | 0.40 | s | C | IEC 60364-4-41 §411.3.2 (Table 41.1); IEC 60909-0 (cmin) |
| C-DB-E1 | In ≤ Iz of the scheduled cable 4C×35 + 16 E | 125 | 112.72 | A | C | IEC 60364-4-43 §433.1 (In ≤ Iz); IEC 60364-5-52 Annex B ratings |
| C-RAS-01 | In ≤ Iz of the scheduled cable 4C×10 | 63 | 52.20 | A | C | IEC 60364-4-43 §433.1 (In ≤ Iz); IEC 60364-5-52 Annex B ratings |
| C-RAS-02 | In ≤ Iz of the scheduled cable 4C×16 | 80 | 69.60 | A | C | IEC 60364-4-43 §433.1 (In ≤ Iz); IEC 60364-5-52 Annex B ratings |
Two screens of the example.
Captured from the ASH ELDAS with the example loaded (release 2.69).
The bench's standards register.
As printed in Annex A of the bench's report (54 documents). Clause texts are not reproduced; each check cites its clause.
| Document | Title | Used for |
|---|---|---|
| IEC 60364-4-41 | Low-voltage electrical installations — Protection against electric shock | Disconnection times (Table 41.1), automatic disconnection in TN systems |
| IEC 60364-4-43 | Low-voltage electrical installations — Protection against overcurrent | Ib ≤ In ≤ Iz (433.1); adiabatic S ≥ I√t / k (434.5.2) |
| IEC 60364-5-52 | Low-voltage electrical installations — Wiring systems | Current-carrying capacity (Annex B tables B.52.x), correction factors, voltage drop (Annex G) |
| IEC 60364-5-54 | Low-voltage electrical installations — Earthing arrangements and protective conductors | CPC size (Table 54.2) |
| NFPA 780-2017 (re-verified against 2023) | Installation of lightning protection systems | Requirement pack: Class I / II materials (23 m), air terminal spacing 6 / 7.6 m, rolling sphere 45 m, down conductors ≥ 2 and ≤ 30 m average spacing, ground rods ≥ 12.7 mm × 2.4 m (3 m depth) (2023: §4.12.2), SPDs (In ≥ 20 kA; 2017 §4.20 = 2023 §4.19) — same values in the 2023 edition held |
| IEC 60909-0 | Short-circuit currents in three-phase a.c. systems — Calculation of currents | Ik3 max (cmax), Ik1 min (cmin), peak factor κ, motor contribution §3.8 — text not in the library; equations as published |
| IEC TR 60909-2:2008 | Short-circuit currents — Data of electrical equipment | §2.6 Table 16 / Fig. 13: ILR / IrM of asynchronous motors (LV ≈ 6.7, MV ≈ 5.5) — library copy |
| IEC 60947-2 | Low-voltage switchgear and controlgear — Circuit-breakers | Breaking capacity Icu, selectivity (Annex A), Im tolerance ±20 % (applied as given in EIG 2018 ch. G §5 — the IEC text is not held) |
| IEC 60947-4-1 | Low-voltage switchgear and controlgear — Contactors and motor-starters | Starter coordination |
| IEC 61439-1 / -2 / -3 | Low-voltage switchgear and controlgear assemblies | Short-time rating Icw, peak factor n (Table 7), forms of separation, DBO |
| IEC 61439-6 | Low-voltage switchgear and controlgear assemblies — Busbar trunking systems (busways) | Busduct rating, Icw / Ipk, voltage drop |
| IEC 60228 | Conductors of insulated cables | Conductor resistance at 20 °C |
… and 42 more documents in the bench's register.
Run the example yourself, then your own project.
The trial opens with the same example project; choose "Load example project" on the first screen. Trial reports and exports carry a watermark.