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Annex 3.1. The highest allowable resistance values of grounding devices in electrical installations. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Rules for the technical operation of consumer electrical installations (PTE)
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Table 36
Object characteristic |
Soil resistivity, r, Ohm×m |
Resistance, Ohm |
Electrical installations with a voltage of 110 kV and above networks with effective neutral grounding, made according to resistance standards |
to 500
more 500 |
0,5
0,002×0,5r |
Electrical installations 3 - 35 kV networks with isolated neutral |
to 500
more 500 |
250/Ip*, but not more than 10 Ohm
0,002r×250/Ip |
Electrical installations of networks with voltage up to 1000 V with dead-earthed neutral voltage: |
|
|
660/380 V |
up to 100 (more than 100) |
15**
(15×0,01r) |
380/220 V |
|
30**
(30×0,01r) |
220/127 V |
|
60**
(60×0,01r) |
Electrical installations of networks with voltage up to 1000 V with an isolated neutral at the power of the power source: |
|
|
over 100 kVA |
to 500 |
50/Ip*, but not more than 4 Ohm |
up to 100 kVA |
more 500 |
50/Ip*, but not more than 10 Ohm |
*Iр - see the note to the table. 34.
** The resistance of the grounding device, taking into account the repeated grounding of the neutral wire, should be no more than 2, 4 and 8 ohms at line voltages of 660, 380 and 220 V, respectively, of a three-phase current source and voltages of 380, 220 and 127 V of a single-phase current source.
See other articles Section Rules for the technical operation of consumer electrical installations (PTE).
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