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P403-3222 Rev. K 4/18

Maximum Protective Ground Resistance

(From Dalziel's Equation)

Time (cycles)

Resistance (milliohms)

700

600

500

400

300

200

100

Graph 1

This chart is based upon C.F. Dalziel's research and widely used industry values. Calculations were made using equation 1 with

the variable being time duration of current flow.

Содержание CHANCE C403-3220

Страница 1: ...countered which are not sufficiently covered in this guide contact A B Chance Company NOTE Because Hubbell has a policy of continuous product improvement we reserve the right to change design and spec...

Страница 2: ...3 SELF TEST PROCEDURE 6 THRESHOLD PROGRAMMING 7 1 Threshold Derivation 7 2 Changing the Threshold 8 TEST SETUP 9 GROUND SET TEST PROCEDURE 10 GROUND SET TROUBLESHOOTING WITH PROBES 11 EXPECTED GROUND...

Страница 3: ...Thoroughly read and understand these instructions before using the Tester 3 Fixed Input Connections When the INPUT SELECT switch is in the fixed position The resistance measurement shown will be the...

Страница 4: ...pply 13 Probe Input When the INPUT SELECT switch is in the PROBE position the resistance measurement shown will be the value of resistance between probe contact points 14 Input Select Switch Allows se...

Страница 5: ...Page 5 of 20 P403 3222 Rev K 4 18 Figure 1 Front Panel of Protective Ground Set Tester Showing Feature Location...

Страница 6: ...SELECT switch in the FIXED position 6 Place the CONTINUOUS TEST switch in the OFF position 7 Press the SINGLE TEST switch 8 The display will show the measured resistance of the self test cable on line...

Страница 7: ...utility MUST select actual work site values for system fault cur rent fault duration and permissible maximum worker body current before attempting to set grounding jumper acceptable limits to assure...

Страница 8: ...be the voltage across the man used to calculate the maximum values for the thresholds This voltage can be adjusted using the CABLE SIZE and the CONTINUOUS TEST switches as described in 5 7 5 Select a...

Страница 9: ...rrent from one fixed input to the other during testing Without the ground set the resulting open circuit prevents the resistance measurement If the ground set is left unconnected and the INPUT SELECT...

Страница 10: ...displayed at the end of the first line of the display 6 Place the INPUT SELECT in the FIXED position 7 Place the CONTINUOUS TEST switch in the OFF position 8 Press the SINGLE TEST switch 9 The display...

Страница 11: ...end 9 The display will show the measured resistance from one probe to the other when contacting the ground set on line 2 of the display in m The red light will illuminate if the ground set resistance...

Страница 12: ...maximum resistance value for protective grounds issued to workers for use in a predefined area For example a nearly equipotential zone can be created by placing a protective ground in parallel with th...

Страница 13: ...ce for a given set of conditions Rj Rm Im If Im Eq 3 Example 1 Assume Rm 1 000 ohmsK 157 If 1 000 Amp t 25 Sec Imax 314 milliamperes fibrillation threshold from Eq 1 With 3 1 safety margin Rj 100 mill...

Страница 14: ...and Graph 1 This chart is based upon C F Dalziel s research and widely used industry values Calculations were made using equation 1 with the variable being time duration of current flow Chart 2 and Gr...

Страница 15: ...tions vol 79 part III 1960 pp 667 673 6 Dalziel C F Massoglia F P LET GO CURRENTS AND VOLT VOLTAGES AIEE Transactions vol 75 part II 1956 pp 49 56 7 Dalziel C F ELECTRIC SHOCK HAZARD IEEE Spectrum Feb...

Страница 16: ...k up breakers maximum operation time 20 cycles 333 sec Utility s Accepted level of safety Vworker max 100 Volts Iworker max 0 100 ampere 100 milliampere from Eq 4 Maximum parallel jumper resistance al...

Страница 17: ...ble Fault Current 6000 16 7 8000 12 5 1000 5000 10000 10000 10 0 12000 8 3 2 860 861 172 86 14000 7 1 3 702 703 140 70 16000 6 3 4 608 608 122 61 18000 5 6 5 544 544 109 54 20000 5 0 6 496 497 99 50 2...

Страница 18: ...alziel s Equation Time cycles Resistance milliohms 700 600 500 400 300 200 100 5 10 15 20 25 30 Graph 1 This chart is based upon C F Dalziel s research and widely used industry values Calculations wer...

Страница 19: ...0 V Max Resistance milliohms Graph 2 This chart represents the maximum allowable resistance of the protective ground based upon the constraint that the maximum voltage drop across the man will never e...

Страница 20: ...20 of 20 P403 3222 Rev K 4 18 Hubbell Chance USA 210 N Allen Street Centralia Mo 65240 1395 573 682 5521 Fax 573 682 8475 Copyright 2016 Hubbell Incorporated 210 N Allen Centralia MO 65240 Printed in...