Flagship Service

Electrical Calculations

We perform transient and steady-state calculations for electrical installations of all voltage classes — short-circuit currents, relay protection, motor starting, arc flash and much more — modelled in ETAP and delivered as stamped, audit-ready reports.

Discuss your tasks
Load FlowIEC 60909 Short CircuitProtection Coordination IEEE 1584 Arc FlashMotor StartingPower QualityStability
What we calculate

A full range of energy-system calculations for design and operation.

As Zimbabwe's captive-power directive turns every major plant into a micro-grid, ZETDC and lenders increasingly demand a single, verified electrical model behind every decision. We build that model once in ETAP and run the full suite of studies on it — so the load-flow, the short-circuit levels, the protection settings and the arc-flash labels all reconcile to one source of truth.

Every calculation we run

Twelve calculations. One model.

Tap any calculation below to see what it answers, the standard it follows, and exactly what you get. Mix and match — request as many as you need.

EC / 01

Load Flow & Steady-State Analysis

Voltage profiles, equipment loading and system losses across every bus.

Know exactly where your network is sagging before you commission anything.

A load-flow study calculates the voltage at every bus, the loading on every transformer and cable, and the real and reactive losses across the system, under the load scenarios that matter to you (peak, normal, minimum). It is the foundation every other study builds on.

  • Per-bus voltage profiles flagged against statutory ±5% limits.
  • Transformer and feeder loading, identifying overloads and spare capacity.
  • Multiple load scenarios (peak / normal / minimum) on one model.
Backbone study · 2–4 weeksRequest this calculation
EC / 02

Short-Circuit Currents (IEC 60909)

Fault levels at every point — so switchgear is rated, not over-rated.

Specify breakers to the actual fault duty — and prove it on paper.

Short-circuit calculation per IEC 60909 determines the prospective fault current at every point in the network for three-phase, line-to-ground and other fault types. It sets the interrupting and withstand ratings your switchgear must meet, and feeds directly into protection and arc-flash work.

  • Three-phase, line-to-ground, line-to-line fault levels.
  • Equipment withstand and breaking-capacity verification.
  • Inputs prepared for protection coordination and arc-flash studies.
Typical · 2–3 weeksRequest this calculation
EC / 03

Protection Coordination & Relay Settings

Time-current curves and relay settings that isolate faults without nuisance trips.

When a fault happens, the nearest device should clear it — not the main incomer.

Protection coordination produces the time-current characteristic (TCC) curves and relay settings that ensure selectivity: the device closest to a fault operates first, keeping the rest of the plant energised. We model this in the ETAP Star module and deliver settings ready to commission.

  • Overcurrent and differential relay settings with full TCC plots.
  • Selectivity verification across the protection hierarchy.
  • Settings sheets formatted for the relay makes you run.
Stamped deliverable · 3–5 weeksRequest this calculation
EC / 04

Arc Flash (IEEE 1584)

Incident-energy levels, PPE categories and approach boundaries at every panel.

Your electricians have a legal right to know the energy they're working in front of.

Arc-flash analysis per IEEE Std 1584 calculates the incident energy released in a fault at each piece of equipment, which dictates the personal protective equipment (PPE) category and the safe approach boundaries. The output is a set of warning labels and a study that stands up to a safety audit.

  • Incident-energy calculation at every working panel.
  • PPE category and arc-flash boundary per location.
  • Printed equipment labels and a stamped report.
Stamped + labels · 3–4 weeksRequest this calculation
EC / 05

Motor Starting

Voltage dip and acceleration checks for large MV and LV motors.

A mill that won't start on a weak feed is a production line that doesn't run.

Motor-starting studies model the voltage dip and acceleration time when large motors — SAG and ball mills, crushers, pumps, compressors — are energised, confirming they will start under your supply conditions and won't drag the bus voltage below what neighbouring equipment can tolerate.

  • Starting voltage-dip and recovery analysis.
  • Acceleration-time and torque verification.
  • Soft-starter / VFD / reactor starting-method comparison.
Typical · 2–3 weeksRequest this calculation
EC / 06

Power Quality & Harmonics

Harmonic-distortion analysis and filter sizing per IEC 61000-4-30 / IEEE 519.

Drives, furnaces and rectifiers inject harmonics that quietly cook your transformers.

Power-quality and harmonic studies measure and model the distortion your non-linear loads push back into the supply, check it against the limits in IEEE Std 519, and size the mitigation — active filters, line reactors, K-rated transformers — needed to bring it within bounds.

  • Harmonic-distortion modelling at the point of common coupling.
  • Compliance check against IEEE 519 limits.
  • Filter and reactor sizing with quoted bills of materials.
Study + measurement · 3–4 weeksRequest this calculation
EC / 07

Reactive Power & Capacitor Optimisation

OCP + OPF optimisation that lifts power factor and cuts losses.

The same kilowatts delivered with fewer losses is money straight back to the bottom line.

Using ETAP's Optimal Capacitor Placement (OCP) and Optimal Power Flow (OPF), we determine where to add reactive compensation and how to set transformer taps to raise power factor, flatten the voltage profile and reduce system losses. In our reference modelling this approach delivered a measured 9.7% loss reduction.

  • Optimal capacitor-bank sizing and placement.
  • Transformer tap optimisation for a flatter voltage profile.
  • Loss-reduction and power-factor-penalty-avoidance quantified.
Optimisation · 3–4 weeksRequest this calculation
EC / 08

Transient & Dynamic Stability

Generator stability and frequency-response checks for captive plants.

When the grid drops and your generators take the load, will they hold?

Transient and dynamic stability studies model how generators and the network respond to disturbances — faults, sudden load changes, loss of the utility supply — checking that machines stay in synchronism and frequency recovers within limits. Essential for any site islanding onto its own generation.

  • Rotor-angle and voltage stability through disturbances.
  • Rate-of-change-of-frequency (ROCOF) and load-shedding response.
  • Island-transition and re-synchronisation behaviour.
Advanced study · 4–6 weeksRequest this calculation
EC / 09

Reliability Analysis

System reliability indices and redundancy assessment.

Quantify how often — and how long — each critical load could go dark.

Reliability analysis evaluates the probability and duration of supply interruption to critical loads, given your network topology and equipment failure rates. It justifies (or challenges) redundancy investment with numbers a board and a lender can weigh.

  • Reliability indices for critical buses and loads.
  • Single-point-of-failure and redundancy assessment.
  • Cost-justified redundancy recommendations.
Typical · 3–4 weeksRequest this calculation
EC / 10

DC Systems & Battery Sizing

Station battery and UPS autonomy calculations.

The protection and control that has to work when everything else fails runs on DC.

DC-system studies size the station battery and charger, and verify UPS autonomy, so protection relays, control systems and critical loads ride through an outage for the required duration. We calculate the duty cycle, battery capacity and voltage-drop on the DC distribution.

  • Battery duty-cycle and capacity (autonomy) sizing.
  • Charger sizing and DC voltage-drop verification.
  • UPS runtime modelling for telecom and IT loads.
Typical · 1–3 weeksRequest this calculation
EC / 11

Current Transformer Saturation

CT sizing and knee-point verification for reliable protection.

A current transformer that saturates in a fault blinds the relay that depends on it.

CT saturation studies verify that your current transformers will reproduce fault current faithfully — without saturating — so the protection relays they feed operate correctly. We check knee-point voltage, burden and accuracy class against the protection scheme's requirements.

  • Knee-point voltage and saturation time-to-saturate checks.
  • CT burden and accuracy-class verification.
  • Re-specification where existing CTs are inadequate.
Focused study · 1–2 weeksRequest this calculation
EC / 12

Earthing & Grounding (IEEE Std 80)

Step- and touch-potential analysis and grounding-grid design.

In a ground fault, a badly-earthed yard can put a lethal voltage under someone's feet.

Grounding studies per IEEE Std 80 design the earthing grid and verify step- and touch-potentials stay within safe limits during a ground fault, accounting for local soil resistivity — important on the karst and variable terrain found across Zimbabwean industrial sites.

  • Soil-resistivity-based grounding-grid design.
  • Step- and touch-potential verification against safe limits.
  • Earth-grid conductor and electrode specification.
Typical · 2–4 weeksRequest this calculation

One verified ETAP model. Every study runs on it.

We don't build a fresh spreadsheet for each calculation. We build your network once in the ETAP power-systems platform — buses, transformers, cables, machines, protection — verify it against site data, then run the full suite of studies on that single model. Results reconcile, because they share one source of truth.

Reports are issued in English, in your template or ours, and can be exported in ETAP, PDF, DWG and other formats.

12+
Calculation types
ETAP
In practice since 2021
118-pg
Dissertation backbone
How we work

Your project, step by step.

A clear four-stage process, agreed before any work starts, so you know exactly what you're getting and when.

1

Bid & scope

We discuss the technical specification and project details so the scope is clear and agreed before the contract is signed.

2

Initial data

We collect and verify the input data — equipment parameters from nameplates, drawings or site measurement — at the project's stage of readiness.

3

Scenarios

For each study we agree the list of network configurations, operating modes and conditions to be calculated, and run them.

4

Results

We prepare and issue the report (English, your template or ours) and can hand over the model with its equipment library in ETAP, PDF, DWG and more.

Why you can trust us

Real models. Real results.

This calculation suite is built on the founder's Master's dissertation (with distinction): a 118-page, ETAP-based study of an industrial power system. Three case studies form its backbone — and they map directly onto the services above.

Case 01 · Load Flow

Power-flow analysis of a 34.5 kV main substation

A 13-bus network modelled across peak, normal and minimum load scenarios — surfacing a bus under-voltage at 87.07% and a transformer loaded to 289.9%.

13 buses · 8 transformers · 3 load scenarios
Case 02 · Optimisation

Optimisation via capacitor placement & optimal power flow

Capacitor banks and transformer tap optimisation (OCP + OPF) applied to the same model to lift power factor and cut system losses.

9.7% loss reduction · vs 5.8% capacitor-only
Case 03 · Protection

Protection coordination across the network

Differential and overcurrent relays coordinated with full time-current characteristic plots in the ETAP Star module.

13 relays · full TCC coordination
Standards & tools we work to
ETAPIEC 60909IEEE 1584IEEE Std 80IEEE 519 IEC 61000-4-30IEEE 1547IEC 61724IPMVPISO 50001 ZWS / ZERA Grid Code
Sample ETAP load-flow study output for a 33/11 kV industrial plant
What you receive

Exactly what's inside every report.

Every study is written so anyone — your team, a regulator, or a bank's engineer — can follow the reasoning and check the result. No black boxes.

  • Stated assumptions, input data and their sources.
  • The full calculation method and the standard applied.
  • Single-line diagram and annotated results.
  • Findings, violations and ranked recommendations.
  • Issued in English · PDF, DWG and native ETAP export.

Tell us the problem. We'll solve it.

Send a single-line diagram and a recent ZETDC bill, and we'll come back with a scoped proposal — which calculations you need, what they'll show, and what they'll cost.