Zentra
SwitchRoom
Zentra · engineering software lab
SR-01 · AVAILABLE NOW

Tools that help engineers think faster.

Zentra builds simulation and design software for electrical engineers, technicians and students. Clear enough to learn from, precise enough to work with.

Explore SwitchRoom Try the live tools
Live circuit · try it12 Ω · 12 V
+ − 12 V switch lamp
V12.0 V
I = V ÷ R1.00 A
P = V × I12.0 W
⊕3design workspaces
◎39learning examples
⌗DXFexport to AutoCAD
⧉1×one-time payment
Product index[01] SWITCHROOM · [02] —

Software built by engineers, for engineers.

Each Zentra product solves one real job well: learn it in minutes, rely on it at work.

UNIT SR-01 AVAILABLE NOW

SwitchRoom

An electrical design suite for Windows. Draw a circuit, see live voltage, current and power, then design 10 electrical systems (solar PV, house wiring, EV charging, gensets, motors, UPS and more) and complete building power distribution in the same app.

⚡
Circuit LabDC · AC · 1φ · 3φ
◈
System DesignPV · wiring · EV · UPS
⌂
Power DistributionMV · MSB · UPS · cables
  • Live simulation of DC, AC, single-phase and 3-phase circuits
  • Diagnostics that say where the fault is and how to fix it
  • Automatic single-line diagrams with cable sizes, voltage drop and breakers
  • Export PNG, SVG and editable DXF for AutoCAD
See plansUpgrade to Pro
Workspaces03
Learning examples39
IN THE LAB

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ROADMAP

Built on one idea

Every Zentra product shows the engineering behind each number, so you learn while you work and can defend every result.

Mission timeline

Built in phases. Shipped with care.

What is live today and what we are building next.

Phase 1: BuildPhase 2: Expand
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02
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04
05
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08
⚡
Circuit LabLIVE
◈
System DesignLIVE
⌂
Power DistributionLIVE
◎
39 learning examplesLIVE
⧉
Online licence portalIN PROGRESS
⚑
Next engineering toolNEXT
Field instruments02 / FREE

Free calculators. Real formulas.

Quick checks you can trust on site or in class. Every result shows the formula behind it.

INSTRUMENT 01 · OHM

Ohm's law & power

Enter any two values. The rest is calculated.

V = I × R · P = V × I · P = I² × R · P = V² ÷ R
INSTRUMENT 02 · ΔV

Cable voltage drop

Copper or aluminium cable at full load. Checks against the common 4 % design limit.

Lab archive06 NOTES

Lab notes: the why behind the numbers.

Short, practical explanations. Tap a note to open it.

N-01
√3

Why 3-phase is 400 V, not 690 V

Three 230 V phases do not simply add up.

Read →
Each phase is 230 V to neutral, but the phases are 120° apart. The voltage between two phases is 230 × √3 ≈ 400 V. That is why a 3-phase motor is rated 400 V while a lamp between one phase and neutral still gets 230 V.
N-02
4%

The 4 % voltage-drop rule

Long, thin cables quietly steal voltage.

Read →
Every metre of cable has resistance, so the load receives less than the supply voltage. Many designs keep the drop within about 4 % (≈ 9 V on 230 V). If it is higher, use a bigger cable size or a shorter route. Motors and LED drivers are the first to complain.
N-03
Ib

Breaker vs cable: who protects whom

The breaker exists to protect the cable.

Read →
Check the chain Ib ≤ In ≤ Iz: design current ≤ breaker rating ≤ cable capacity. A 32 A breaker on a cable that can only carry 24 A will let the cable overheat before it trips.
N-04
pf

Power factor: the hidden current

Same kW, more amps.

Read →
Motors draw extra reactive current. With I = P ÷ (V × pf), a 2 kW motor at pf 0.8 on 230 V draws about 10.9 A instead of 8.7 A. Cables and breakers must be sized for the real current, not just the kW.
N-05
PV

Solar strings: cold Voc, hot Vmp

Panels change voltage with temperature.

Read →
On a cold morning the open-circuit voltage rises, and it must stay below the inverter's maximum DC voltage. On a hot afternoon the working voltage falls, and it must stay above the MPPT minimum. A good string size satisfies both.
N-06
∥

Series vs parallel in one minute

Why one bad bulb used to kill the whole string.

Read →
In series, the same current flows through every part and voltages add up, so one break stops everything. In parallel, every branch gets the same voltage and currents add up. Houses are wired in parallel so each appliance works on its own.
Unit catalogueSR-01 · SwitchRoom pricing

Pick the plan that fits your work.

One-time licence key. Works offline. One licence is for one PC.

BASIC
RM48

For students and anyone learning circuits.

  • Circuit Lab: DC, AC, 1-phase and 3-phase
  • Live diagnostics with step-by-step fixes
  • 15 starter examples: Ohm's law, house DB, LEDs, 555 timer, DOL starter and more
  • Save, open and export (PNG, SVG, DXF)
  • System Design: view only
  • Power Distribution: view only
PRO

For contractors, engineers and consultants.

  • Everything in Basic
  • All 39 examples: motor starters, ATS + genset, VFD, grid-tie solar, PLC-style logic
  • System Design: solar PV, house wiring, EV, genset, motors, PFC, UPS, lighting, earthing and aircond
  • Power Distribution: MV to final boards, UPS and generators
  • Cable sizing, voltage drop and protection checks
  • Building wizard: commercial, factory, residential high-rise or data centre
Already have Basic? Upgrade instead →

Payments by FPX online banking, DuitNow and cards. Your key is shown on screen right after payment and sent to your email.

Not sure yet? Download the free 3-day trial: Basic features, with a live days-and-hours countdown (saving and export unlock with a licence).

Field kitSR-01 · Download

Try it free for 3 days.

One installer for everyone. Without a key it runs as a 3-day trial; your licence key turns the same app into Basic or Pro.

  1. Download and installWindows 10 or 11, 64-bit. No account needed.
  2. Press “Start 3-day free trial”A counter in the app shows the days and hours left.
  3. Like it? Press Buy inside the appThis page opens with your PC ID filled in. Pay, paste the key, done.
SwitchRoom
Windows 10 / 11 · 64-bit
Download free trial

Already bought? It is the same installer. Paste your key on the licence screen.

Licence controlBASIC → PRO

Basic → Pro in three steps.

Keep your licence number and your PC. Pay only the upgrade price.

  1. Paste your Basic keyIn SwitchRoom, the upgrade button copies it for you.
  2. Pay the upgrade priceFPX online banking, DuitNow or card.
  3. Paste your Pro key in the appEvery workspace unlocks instantly. No reinstall.
Licensed to
Licence no.
Current plan
PCs
Upgrade price
BriefingFAQ

Questions, answered.

Q-01How many computers can I use?

One licence is for one PC. Your key is made for that PC, so it will not work on another computer. Changing to a new PC? Open SwitchRoom on the new PC and choose “Move my licence to this PC”, or email us your licence number and the new PC ID shown on the licence screen.

Q-02Do I need internet to use SwitchRoom?

No. Once your key is entered, SwitchRoom works fully offline.

Q-03How do I receive my key?

Right after payment, the key appears on screen and is sent to your email. Paste it into SwitchRoom to activate.

Q-04Can I upgrade from Basic to Pro later?

Yes. Paste your Basic key in the Upgrade section, pay the upgrade price and you get a Pro key with the same licence number.

Q-05Which language is the app in?

English. Every label, report and drawing is in English, the language used on Malaysian electrical drawings and standards. This website is available in English and Bahasa Melayu.

Q-06Is there a free trial?

Yes. Install SwitchRoom and choose “Start 3-day free trial”. For 72 hours you get the Basic features: Circuit Lab with 15 examples, and a view-only look at System Design and Power Distribution. Saving and export need a licence. After the trial, buy Basic or Pro and enter your key to continue.

Q-07Is it suitable for real installations?

SwitchRoom is a learning and design-check tool. Real installations must still be designed, checked and tested by qualified, licensed persons following local regulations.

Contact

Talk to us.

Questions about licences, invoices or features? Email us and include your licence number if you have one.

Comms channel

Email only. We do not take phone calls, so every answer is in writing for your records.