Substation engineering, without the spreadsheet wrestling.
Calculators and QA templates for substation design, testing and commissioning — built by a practising power engineer. Buy once, download instantly, use forever.
Voltage Drop
Quick demo
Voltage drop—
As percentage—
Compliance—
Teaser only — the full tool also sizes the cable for you. Open it →
AS/NZS · IEC · IEEE methodsInstant downloadOne-time paymentBuilt for substations
The toolkit
Substation calculators and QA templates, in one place
Four working calculators and a full substation ITP/ITR pack — properly built and checked, so you stop maintaining fragile workbooks someone made in 2014. Here's the one engineers reach for first.
AS/NZS 3008 · Copper & Aluminium
Cable Sizing & Voltage Drop Calculator
Enter the load, the run, and the installation conditions. Get the smallest compliant conductor, voltage drop, and current-carrying capacity with derating already applied.
Auto-recommends the smallest size that passes
Ambient temperature & grouping derating built in
Voltage drop and capacity, shown side by side for every size
Transparent working you can sanity-check before sign-off
$49AUD · one-time · free updates
Why Switchyard
No subscriptions, no fluff, no guesswork
— FROM THE FIELD
Built by a practising engineer
These tools come out of real substation and design work, not a generic template marketplace.
— OWN IT
Pay once, keep it
One-time price and instant download. No seat licences, no bill creeping up every year.
— CHECKED
Transparent & verifiable
Every calculation shows its working so you can sanity-check the result before you sign off.
Flagship tool · Live
Cable Sizing & Voltage Drop Calculator
Enter your circuit and installation conditions. The tool finds the smallest copper or aluminium conductor that satisfies both current-carrying capacity (with derating) and voltage drop, and shows every size so you can see what governs.
Inputs
Project details (optional · for report)
All standard sizes — at your conditions
Size
Derated I (A)
Vd
Vd %
Result
Indicative design aid — verify before you build. This tool uses physics-based voltage-drop maths and representative conductor and current-rating values for preliminary design. It does not reproduce the AS/NZS 3008.1.1 tables, and ratings vary with the exact installation method, cable construction, depth, soil resistivity and circuit grouping. Final cable selection must be checked against the current edition of AS/NZS 3008 by a competent person. Switchyard uses R at 75 °C, representative reactance, and standard derating methodology (rating × ambient factor × grouping factor).
The kit
Substation tools, drawn straight from the job
Four working calculators and a complete QA template pack — every one ready to use right now, built for substation and HV work.
/ 01
Cable Sizing & Voltage Drop
Auto-sizes copper or aluminium to AS/NZS 3008 with derating and voltage drop in one pass.
$49
/ 02
Fault Current Calculator
Prospective short-circuit current at every board, with impedance build-up shown step by step.
$49
/ 03
Transformer Sizing & Fault
Full-load currents both windings, base impedance and transformer-limited through-fault.
$39
/ 04
Earthing & GPR (IEEE 80)
Grid resistance, ground potential rise and tolerable step/touch voltages for a quick screen.
$59
/ 05
Substation ITP & ITR Pack
FAT/SAT plan plus eighteen substation & HV record forms, ready to brand.
$39
/ 06
Complete Toolkit
All four calculators and the full template pack — one price, free future tools.
$129
About
Tools by someone who has to use them too
Switchyard exists because the same calculations get rebuilt in fragile spreadsheets on every project, in every office, by every engineer. The maths doesn't change — so why does everyone keep re-deriving it?
Each tool here started as something needed on real power and substation work: sizing cables, recording inspections, documenting SCADA displays. They've been cleaned up, checked, and packaged so you can buy one once and stop reinventing it.
No subscriptions. No accounts to manage. You pay once, download the tool, and own it. Calculations show their working, because a black box is no use when your name goes on the design.
At a glance
Based Melbourne, AU
Focus Substation & HV
Methods AS/NZS · IEC · IEEE
Delivery Instant download
Licensing One-time, own it
Stay in the loop
New tools & updates
Drop your email for a heads-up — and a discount — whenever a new substation tool ships.
No spam — launch news only. Unsubscribe anytime.
Flagship tool · Live
Prospective Fault Current Calculator
Define your source — a distribution transformer or a known supply fault level — then chain the cable path board by board. The tool builds up the impedance and returns the three-phase symmetrical fault current, peak current and an indicative line-to-neutral fault at every node, so you can verify switchgear and device short-circuit ratings.
Source & cable path
Cable path (source → boards)
Project details (optional · for report)
Fault current at each node
Node
Z (mΩ)
X/R
I″k3 (kA)
Ip (kA pk)
I_LN≈ (kA)
Indicative design aid — verify before you rely on it. Calculations use the impedance method with conductor resistance at 20 °C (for maximum fault current), representative reactance, and the IEC 60909 peak factor κ. The line-to-neutral figure is approximate and assumes a neutral of equal cross-section to the phase; it is intended for a first protection check, not a substitute for a full sequence-component study. Confirm transformer data with the nameplate and verify equipment ratings and protection grading against a complete fault study and the current AS/NZS standards.
Product · Inspection & test
ITP & ITR Template Pack
A complete, editable set of inspection and test documents for substation and HV plant — a FAT/SAT-structured ITP plus eighteen ready-to-use record forms spanning cables, earthing, transformers, circuit breakers, instrument transformers, capacitor banks, NERs, protection, SCADA, DC systems, comms and distribution boards. Built for power work, not generic construction.
Editable Word (.docx) · A4 · Print-ready
Stop rebuilding the same QA paperwork on every project
The plan tells you what to inspect, against what criteria, who signs, and where the hold and witness points sit. The records are the check-sheets that get filled in on site. Both are branded with a placeholder header you swap for your logo and document numbers.
FAT/SAT-structured ITP matrix with hold / witness / surveillance points
Eighteen substation & HV ITR forms — from cables and earthing to transformers, breakers, CT/VT, protection, SCADA and DC systems
Acceptance criteria left blank to complete against your spec and the applicable AS / IEC standards
Fully editable: rename, re-brand, add or remove rows
Installation checks plus insulation resistance and continuity record.
ITR-03
Earthing & Bonding
Conductor, connection and earth resistance / continuity record.
ITR-04
Switchboard / Switchgear
Installation, wiring, interlock, function and IR inspection record.
ITR-05
Power Transformer SAT
Ratio, winding R, IR/PI, Buchholz, OLTC, oil, earthing and withstand.
ITR-06
Protection Relay Test
Secondary injection: metering, element pickup/timing, trips, CBF, AR.
ITR-07
SCADA / RTU / HMI
End-to-end point-to-point, alarm, indication and functional test.
ITR-08
HV Circuit Breaker SAT
Contact resistance, IR, withstand, timing, mechanism and integration.
ITR-09
Instrument Transformer
CT/VT ratio, polarity, magnetisation, IR and secondary wiring.
ITR-10
Disconnector / Earth Switch
Operation, interlocks, main-circuit resistance, IR and earthing.
ITR-11
Surge Arrester
Inspection, segment IR, earth connection and torque checks.
ITR-12
DC Supply & Battery
Battery float/impedance, capacity discharge, charger and DC board.
ITR-13
Substation Earthing System
Grid resistance, step/touch injection, bonding and secondary earth bar.
ITR-14
Capacitor Bank
Rack IR, reactor/CT IR, capacitance per leg, step switch and unbalance.
ITR-15
Neutral Earthing Resistor
Resistance, earthing, IR and torque — plus bypass CB reference.
ITR-16
Fibre Optic Comms
Per-core insertion loss, OTDR trace and end-to-end link test.
ITR-17
AC / DC Distribution Board
Change-over, IR, earth leakage, thermal survey and alarms.
ITR-18
Pre-Energisation & Commissioning
Switching, controlled energisation, on-load CT/VT and proving.
ITR-19
Final Inspection & Handover
Clean-up, joint inspection, deficiency close-out and as-built handover.
Templates, not a substitute for engineering judgement. Acceptance criteria and references are starting points based on standard AS/NZS methodology. Review and adapt every form against your project specification and the current editions of the applicable standards before use.
Substation tool · Live
Transformer Sizing & Through-Fault Calculator
Enter the transformer rating and voltages to get the full-load current on both windings, the base and transformer impedances, and the transformer-limited through-fault current that downstream switchgear must withstand.
Inputs
Project details (optional · for report)
Calculated quantities
Quantity
HV side
LV side
Indicative design aid. Through-fault current here assumes an infinite source (transformer impedance only), which is the conservative maximum for switchgear rating; for a network-limited value, add the source impedance in the fault current tool. Confirm rating, voltages and %Z against the transformer nameplate, and verify equipment ratings against a full study and the applicable standards.
Substation tool · Live
Earthing & Ground Potential Rise Calculator
A first-pass IEEE 80 screen for a substation earth grid: estimates grid resistance (Sverak), the ground potential rise during an earth fault, and the tolerable step and touch voltages — so you can tell early whether a full mesh analysis is needed.
Inputs
Project details (optional · for report)
Results
Quantity
Value
Screening tool — not a full earthing design. Grid resistance uses the Sverak equation and tolerable voltages use the IEEE 80 body-current formulas (50/70 kg). It does not compute actual mesh or step voltages, soil layering, or current division. A GPR below the tolerable touch voltage indicates the site is safe by inspection; if it exceeds it, a full IEEE 80 / AS 2067 mesh and step-voltage analysis by a competent person is required.
Pricing
Own your tools. Don't rent them.
The established AU calculators are subscriptions — typically $190 to $490 per seat, every year. Switchyard is a one-time purchase: buy it, download it, keep it, and get free updates. No login, no watermark, no annual invoice.
Single tool
One calculator
$49
AUD · one-time
Any one calculator — cable, fault, transformer or earthing
Branded report export
Free updates · no signup
Best value · most popular
Complete toolkit
$129
AUD · one-time
Every calculator on the site
The full ITP & ITR template pack
All future tools added free
Branded report export on every tool
For firms
Firm licence
$399
AUD · one-time
Everything in the toolkit
Use across your whole engineering team
Priority email support
One invoice — no per-seat renewals
How it compares
Typical subscription tool
Switchyard
Pricing model
$190–490 per seat / year
One-time — own it
Cost over 3 years (1 seat)
$570–1,470
$129 once
Sign-up / login
Required
None — open and use
Free version watermark
Often
No watermark
Power & substation depth
Generic LV
Built for it
QA templates (ITP / ITR)
Separate vendor
Included in toolkit
Competitor pricing reflects publicly listed plans and varies; one-time pricing above is indicative and editable.
Questions
How accurate are the calculators?
They use physics-based maths (voltage drop from conductor resistance and reactance; the impedance method for fault current) with representative AS/NZS-aligned values, and they show their working. They're a design aid: every result must be verified against the current edition of the relevant Standard by a competent person before sign-off.
Do they reproduce the AS/NZS 3008 tables?
No. The Standard's tables are Standards Australia's copyright. The tools compute from first principles and use indicative ratings, which is why a final check against the Standard is required — and why they're safe to use and sell.
One-time price — do I really keep it?
Yes. You download the tool and it's yours, including future updates. There's no per-seat annual renewal.
What format are the templates?
Editable Microsoft Word (.docx), A4, print-ready, with a placeholder header and blank document-number fields so you can brand them as your own in minutes. Excel versions are available on request.
Refunds?
If a tool doesn't do what the page says, email within 14 days for a refund — these are professional tools, not a lucky dip.