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Grounding Grid Design: DECREMENT FACTOR
FAULT DUR 0.3S X R 10 to FAULT DUR 0.5S X R 20
IEEE 80 grounding grid design parameters including touch/step voltage safety limits (50 and 70 kg body weight), decrement factors by X/R ratio, and typical soil resistivity values by soil type.
| parameter type | condition | decrement factor (dimensionless) | limiting value | unit |
|---|---|---|---|---|
| DECREMENT FACTOR | FAULT DUR 0.3S X R 10 | 1.0433 | 1.0433 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.3S X R 20 | 1.0848 | 1.0848 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.3S X R 30 | 1.1248 | 1.1248 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.3S X R 40 | 1.1629 | 1.1629 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.4S X R 10 | 1.0326 | 1.0326 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.4S X R 20 | 1.0643 | 1.0643 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.4S X R 30 | 1.095 | 1.095 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.4S X R 40 | 1.1248 | 1.1248 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.5S X R 10 | 1.0262 | 1.0262 | dimensionless |
| DECREMENT FACTOR | FAULT DUR 0.5S X R 20 | 1.0517 | 1.0517 | dimensionless |
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