Step 1 — Design basis
Project & Supply
Design basis to IEC / IS — machinery electrical equipment to IEC 60204-1, assembly to IS/IEC 61439, conductors to IEC 60364-5-52, devices to IEC 60947. Built to the Siemens control-panel design guide, mapped to the IEC/IS framework.
Supply systemIEC / IS
Prospective fault current sets the required breaking capacity (Icu) of the incomer and the assembly's rated conditional short-circuit current Icc (IS/IEC 61439-1, IEC 60947-2). Ambient drives conductor derating (IEC 60364-5-52).
Project details
The design basis feeds every module. Motor sizing (Tab 2) and the incoming supply / feeder (Tab 3) both read the supply voltage and fault level set here.
Step 2 — Power circuit
Motor Branch-Circuit Sizing
Per IEC 60204-1 / 60364-5-52: rated current from motor kW, efficiency and power factor drives the power conductor (ampacity, IEC 60364-5-52), the overload relay (set to rated current, IEC 60947-4-1) and the disconnect (AC-23, IEC 60947-3). Short-circuit protection follows the manufacturer's Type 2 coordination.
Motor schedule
| Motor | kW | Volts | Eff η | PF | I₁ / step A | Qty | |
|---|---|---|---|---|---|---|---|
Rated current Ie = P / (√3 · U · η · cosφ). Conductor is sized on IEC 60364-5-52 ampacity (method C reference) — apply your installation-method and grouping derating and observe minimum CSA (≥1.5 mm²). These currents feed the feeder totals on Tab 3.
Step 3 — Non-motor loads
Non-motor & Transformer Loads
Heaters, lighting, socket outlets, control / auxiliary transformers and drive inputs. Each is sized by its rated current per IEC 60364-5-52 / 60204-1; the totals feed the incoming supply & feeder on the next tab.
Non-motor load schedule
| Load | Type | Ph | Rating | Iₑ / step A | Qty | |
|---|---|---|---|---|---|---|
Resistive / heater and lighting: I = P / (√3·U) [3-ph] or P / 230 [1-ph]. Transformer: primary I = S / (√3·U); size protection above inrush (per manufacturer). Drive input ≈ kW / (√3·U·0.95); protection per the drive manual. Socket / other: enter the rated current directly.
Step 3 — Incoming supply
Incoming Supply, Disconnect & Feeder
Per IEC 60204-1 Cl 5.3 and IS/IEC 61439: the total connected load, reduced by a diversity (rated diversity) factor, gives the maximum demand. That sizes the incoming conductor, the main disconnecting device, the incomer protective device (with breaking capacity ≥ fault level) and the assembly rated current.
Load & diversity
Motor load
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Non-motor load
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Total circuits
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Motor load comes from the Motors tab; non-motor load from the Non-motor & Transformer Loads tab. Both are summed into the total connected load below.
IEC 61439-2 assumed loading (rated diversity factor) by number of main circuits: 2–3 → 0.9, 4–5 → 0.8, 6–9 → 0.7, ≥10 → 0.6. Override with your measured demand factor if known.
Maximum demand
Total connected
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Circuits n
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Diversity factor
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Maximum demand
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Largest motor
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Incoming supply & main devicesIEC 60204-1 Cl 5.3
Sized for maximum demand —IEC 60204-1 / 61439 / 60947
The main disconnecting device (IEC 60204-1 Cl 5.3.2/5.3.3) must carry the maximum demand and be able to switch the stalled-rotor current of the largest motor together with the running currents of the others. The incomer breaking capacity Icu must exceed the prospective fault current; the assembly is verified to Icc per IS/IEC 61439-1.
Assembly short-circuit ratingIS/IEC 61439-1
Prospective fault Icp
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Peak factor n
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Peak withstand Ipk
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Short-time Icw (1s)
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Conditional Icc
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Peak factor n from IS/IEC 61439-1 Table 7 (ratio Ipk/Icw: ≤5 kA→1.5, ≤10→1.7, ≤20→2.0, ≤50→2.1, >50→2.2). Busbars, supports and the enclosure must withstand Ipk. Provide either a rated short-time withstand Icw ≥ Icp (typically ACB-protected), or a rated conditional short-circuit current Icc where the incomer's current-limiting device holds the let-through I²t and peak within the assembly's capability.
Step 5 — Control circuit
Control-Circuit Sizing
Per IEC 60204-1 Cl 9: AC control circuits are supplied from a control transformer with electrically separate windings. The transformer is sized from the continuous (sealed) and inrush VA burden of every coil, lamp and auxiliary supply — for any brand of device — and its primary/secondary protection and control conductor follow.
Control supply
IEC 60204-1 Cl 9.1.1 recommends a separate-winding transformer for AC control; 24 V PELV/SELV is preferred for operator safety. The inrush factor is how much momentary VA the transformer can deliver while holding ~85% secondary voltage so contactors pull in reliably — confirm from the transformer datasheet.
Control transformer & protection
Sealed (cont.) VA
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Inrush VA
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Required VA
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Transformer
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Control device schedule
| Device | Inrush VA each | Sealed VA each | Qty | Σ inrush | Σ sealed | |
|---|---|---|---|---|---|---|
Enter inrush and sealed (holding) VA per device from the component datasheet — works for any brand of contactor, relay, solenoid, lamp or auxiliary supply. Pilot lamps and PLC supplies have inrush ≈ sealed. Primary protection must withstand transformer inrush (curve-D MCB or gG fuse); secondary protection protects the control conductors, minimum 0.75 mm² (IEC 60204-1 Cl 12).
Step 6 — Earthing
Grounding & Protective Bonding
Per IEC 60204-1 Cl 8 and IEC 60364-5-54: the protective (PE) conductor is sized either from the phase conductor cross-section (table method) or by the adiabatic calculation from the fault current and clearing time. The larger governs. Protective bonding continuity must be verified by test.
PE by table methodIEC 60204-1 Table 1
Main phase conductor
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Main PE conductor
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SPE from phase cross-section S: S ≤ 16 → SPE = S · 16 < S ≤ 35 → 16 mm² · S > 35 → S/2 (same material). Minimum 2.5 mm² (mechanically protected) or 4 mm² (unprotected), IEC 60364-5-54 §543.1.1. Each outgoing circuit's PE follows the same rule from its own phase conductor.
| Phase S (mm²) | PE (mm²) |
|---|
PE by adiabatic calculationIEC 60364-5-54 §543.1.2
k factor
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S = √(I²t)/k
—
PE (adiabatic)
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S = √(I²·t) / k. With a current-limiting SCPD use the device's actual let-through (much less than prospective fault × full time). k per IEC 60364-5-54: Cu/PVC 143, Cu/XLPE 176, Al/PVC 95, Al/XLPE 116.
Main PE bar, earthing terminal & bondingIEC 60204-1 Cl 8.2
Governing protective conductor —larger of table & adiabatic
The protective bonding conductor connects all exposed conductive parts to the main PE terminal. Continuity of the protective bonding circuit shall be verified by test (IEC 60204-1 Cl 18.2.2) — typically injecting ≥ 10 A for a period, with a resistance consistent with the conductor length and cross-section. Supplementary equipotential bonding per IEC 60364-5-54 §544.
Step 7 — Wiring
Conductors, Wiring & Clearance/Creepage
Per IEC 60364-5-52 and IS/IEC 61439 / IEC 60664-1: conductor cross-section from the design current after ambient and grouping derating, conductor identification (IEC 60204-1), and the minimum clearance and creepage distances for the rated impulse voltage and pollution degree.
Ampacity & deratingIEC 60364-5-52
Ambient factor
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Grouping factor
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Conductor
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Required base ampacity = design current / (ambient × grouping). The conductor is the smallest CSA whose reference ampacity (method C) meets it; its derated ampacity is shown. Ambient factors per Table B.52.14, grouping per Table B.52.17.
Clearance & creepageIEC 60664-1
Min clearance
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Min creepage
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Clearance (through air) from Uimp per Table F.2; creepage (over surface) from the working voltage and pollution degree, material group IIIa, per Table F.4. Verify busbar & terminal spacings meet these for IS/IEC 61439 dielectric verification.
Conductor identification (IEC 60204-1 Cl 13)
Colours are the IEC 60204-1 recommendations for internal panel wiring — used for any brand of conductor. Green-and-yellow is reserved exclusively for the protective conductor; light blue for the neutral.
Step 8 — Enclosure
Enclosure, Forms of Separation & Thermal
Per IS/IEC 61439 and IEC 60890: the form of internal separation, the ingress protection (IP), the temperature rise from the installed power loss, and the arc-flash assessment. Forms and IP apply to any brand of enclosure.
Form of separationIS/IEC 61439-2
The form of separation defines how busbars, functional units and terminals are segregated. Higher forms ease maintenance and reduce internal fault propagation but cost more. IP is the enclosure's dust/water ingress rating (IEC 60529).
Temperature riseIEC 60890
Cooling surface
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Temp rise ΔT
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Internal temp
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Arc-flash assessmentIEEE 1584 · IEC 61439
Arc energy proxy
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∝ I·t
Relative risk
—
!
Incident energy and PPE category must come from a full IEEE 1584-2018 study — this screen only indicates relative severity, which scales with fault current × clearing time. The primary mitigation is reducing clearing time (faster incomer, zone-selective interlocking, or an arc-flash relay), not increasing the device rating.
Panel size & sheet weight
Weight = surface area (all faces + mounting plate, +15% for flanges, stiffeners & gland plates) × gauge × 7.85 kg/m²·mm. Dimensions come from the Temperature-rise card above; press “Suggest size” to estimate them from the capacitor step count.
Enclosure & fabrication costingfeeds Costing tab
All rates are indicative — edit to your current market. Sheet & fabrication scale with the panel weight; powder coating with surface area. This total carries into the Costing & Quotation tab automatically.
Step 9 — Reactive power
Capacitor & Harmonic-Filter Panel — Step Builder
Per IEC 61921 / IS 13340, IEC 60831 & IEC 61642: build the panel step by step. Fixed bank or automatic multi-step; each step can be plain or reactor-connected (detuned) and can be a different kVAr. The tool sizes each step's capacitor, reactor, contactor and fuse, then totals the panel for the incomer and busbar.
Panel setup
Add each step below with its kVAr and whether it has a detuning reactor. Detuning tunes below the 5th harmonic (7% -> 189 Hz) to avoid resonance; plain steps have no reactor. Mix them freely.
Panel totalsfor incomer & busbar
Total reactive
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Steps
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Capacitor order Σ
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Total current
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Incomer (design)
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APFC relay
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Incomer sized at 1.43 x total step current (IEC 61921 rating factor). Add the specific makes of contactors, fuses, reactors, capacitors and the APFC relay from the Component Library, then price them on the Costing tab.
Step schedule
| Step | kVAr | Type | Cap order kVAr | Reactor kVAr | Current A | Design A | Contactor A | Fuse A | |
|---|---|---|---|---|---|---|---|---|---|
Capacitor order = kVAr x (UCn/Un)² x (1-p); reactor ≈ p x capacitor order; step design current = 1.43 x step current for the contactor (AC-6b capacitor duty) and fuse. Confirm against manufacturer selection tables.
Step 10 — Library
Component Library
Your brand-agnostic price book — every make and type of protective gear, switching device, capacitor, reactor, meter or accessory, with technical specification, dimensions, price and discount. Populate it once; the costing & quotation tab draws from it. Drag-drop a CSV to bulk-load.
Component catalogue
| Section | Make | Type / model | Rating | Dims | Specification | Unit ₹ | Disc % | Net ₹ |
|---|
Add sections, brands and types freely — every field is editable. Discount is applied here; the quotation uses the list price and keeps the discount as your margin.
Step 11 — Commercial
Costing & Quotation
Build the bill of materials from the library, apply your costs and margin, and export the quotation — itemised (BOQ, individual prices) or as a package (total only). Discount applies to your internal cost; the customer quote uses list prices.
Your company
⤓ Click to upload
Customer
Bill of materials
| Item / description | Qty | List ₹ | Disc % | Amount ₹ (net) |
|---|---|---|---|---|
Charges, margin & tax
Cost, discount & profitinternal
Your cost
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Discount benefit
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Est. profit
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Quotationitemised
Build plan
Design Roadmap — IEC / IS
This tool follows the Siemens control-panel design guide across its 15 chapters, built in phases and mapped to the IEC / IS framework. Phases 1–2 are live; the rest follow.
