Ground Potential Rise Screen (IEEE 80)
Ground potential rise in a substation yard.
Example
You enter
- Grid current I_G (A) 200
- Grounding-grid resistance R_g (ohm) 0.5
- Tolerable touch voltage (V, from step-touch-voltage; 0 to skip) 200
You get
- Ground potential rise 100 V
- Margin v 100
Details, formula, and sources
GPR = grid_current x grid_resistance, screened against the tolerable touch voltage. The IEEE 80 shortcut - a GPR at or below the tolerable touch means no yard point can exceed it, so no mesh/step analysis is needed. A 200-A grid current on a 0.5-ohm grid rises just 100 V (passes a 200-V limit outright); a 5,000-A fault on a 1-ohm grid rises 5,000 V (25x the limit, full mesh/step study required). A screen, not a grounding design.
gpr_v = grid_current_a x grid_resistance_ohm; safe_by_gpr = tolerable_touch_v > 0 AND gpr_v <= tolerable_touch_v.
IEEE Std 80 ground potential rise, by name.
IEEE 80 is available through IEEE; the ground-potential-rise relation is a published grounding-study screen.
Estimate. AHJ and licensed professional govern.
Field names used by the API: grid_current_a, grid_resistance_ohm, tolerable_touch_v, gpr_v, margin_v
- GPR shortcut a GPR <= the tolerable touch voltage clears the whole yard without mesh/step analysisIEEE Std 80
- Grid current I_G is the portion of fault current returning through the grid to remote earth, not the total faultIEEE Std 80