Which model and which limits are used?

The ground grid uses a uniform-soil simplified model, with the allowable touch and step voltages of GB/T 50065-2011 / IEEE Std 80-2013 as the criteria; the loop impedance path uses 50 Hz theoretical conductor impedances and the disconnection requirement of GB 50054-2011 §5.2 / IEC 60364-4-41. Layered soil, a finite-element potential field and lightning-impulse earthing are explicitly not modelled and the page states this.

Why is the ground potential distribution not drawn?

Because the engine does not solve a numerical potential field: the page shows the scalars the model really produces — R_g, GPR, touch and step voltage and their allowable values — instead of a coloured potential map that would have to be invented. Where an input is missing the result reads unknown rather than zero, so an incomplete design cannot be mistaken for a passing one.

Grounding & safety — GPR, touch/step voltage and earth-fault loop impedance

Two checks a substation or factory distribution design cannot skip. (1) Ground grid: earth resistance R_g, ground potential rise GPR and mesh/touch and step voltage are computed with the uniform-soil simplified model and compared with the allowable values of GB/T 50065-2011 §3.4 and IEEE Std 80-2013 §8.3. (2) Earth-fault loop impedance: Zs along the phase and protective conductor paths is checked against the disconnection requirement of GB 50054-2011 §5.2 / IEC 60364-4-41. Enter nameplate and grid data; every value carries its basis and standard number, missing data is shown as “—” and is never replaced by zero.

Inputs (reference case)

The grid block is a pure formula input set; the loop-impedance block uses a reference topology (grid → transformer → LV switchgear → load, LV cables with a PE core). Only the parameters you type are sent; anything left blank stays blank (the engine then reports unknown, it does not guess).

RequiredRecommendedLeft bar: blue = required, gold = recommended. Optional and advanced fields are collapsed by default.

Ground grid — earth resistance R_g, GPR, touch and step voltage

Soil resistivity ρ (Ω·m)Required= 150 Ω·mGround grid area A (m²)Required= 2500 m²Earth fault current I_f (A)Required= 5000 A

Mesh spacing D (m)Recommended= 5 mNumber of parallel conductors nRecommended= 11 Conductor diameter d (m)Recommended= 0.02 mBurial depth h (m)Recommended= 0.5 m

Earth-fault loop impedance Zs — indirect-contact protection

Transformer rating (kVA)Required= 1000 kVAImpedance voltage u_k (%)Required= 6 %Load of the checked loop (kVA)Required= 400 kVALV cable length (m)Required= 40 mLV cable phase section (mm²)Required= 50 mm²

Body weight (kg)

Scope and limits: the ground grid uses a uniform-soil model (no layered soil, no finite-element potential field, no lightning impulse earthing); the loop impedance uses 50 Hz theoretical conductor impedances. Where inputs are missing the result is “unknown” rather than an assumed value, and the grid potential distribution is not drawn because the engine does not solve a numerical potential field.

Frequently asked questions

What can this calculator do?: Two checks. (1) Ground grid: enter the soil resistivity, the grid area and the earth-fault current — plus mesh spacing, conductor count and diameter, burial depth and fault duration if you have them — and the uniform-soil simplified model returns the earth resistance R_g, the ground potential rise GPR and the mesh/touch and step voltages, each compared with the allowable values of GB/T 50065-2011 / IEEE Std 80-2013. (2) Loop impedance: the earth-fault loop impedance Zs and the disconnection check of GB 50054-2011 §5.2 / IEC 60364-4-41. Typical uses: substation earth-grid design, a factory distribution earthing review, and documenting a touch/step voltage compliance check. A missing input gives an unknown result, never an assumed value.
Which model and which limits are used?: The ground grid uses a uniform-soil simplified model, with the allowable touch and step voltages of GB/T 50065-2011 / IEEE Std 80-2013 as the criteria; the loop impedance path uses 50 Hz theoretical conductor impedances and the disconnection requirement of GB 50054-2011 §5.2 / IEC 60364-4-41. Layered soil, a finite-element potential field and lightning-impulse earthing are explicitly not modelled and the page states this.
Why is the ground potential distribution not drawn?: Because the engine does not solve a numerical potential field: the page shows the scalars the model really produces — R_g, GPR, touch and step voltage and their allowable values — instead of a coloured potential map that would have to be invented. Where an input is missing the result reads unknown rather than zero, so an incomplete design cannot be mistaken for a passing one.