To arrange the workplace and provide safe operation of the plasma cutting machine by the personnel, you have to make a series of preparations. An essential issue is the presence of a functional grounding device meeting several requirements.
Further, we are going to consider which requirements have to be taken into account and what solution was offered by the ZANDZ Technical Center.
Initial data:
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facility: plasma cutting machine;
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region: Moscow Region;
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soil resistivity: 100 Ohm*m.
Task:
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to calculate functional grounding arrangement with the resistance not more than 1 Ohm;
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the distance to the machine should not be more than 6 m.
Solution:
Functional grounding arrangement for the plasma cutting machine is made in compliance with:
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Technical requirements to preparation of the premise and personnel for startup operations with the AMN plasma cutting equipment.
A set of measures to ensure the requirements to the functional grounding system for the plasma cutting machine is represented by the following solutions:
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installation of 5 x 27 m deep vertical grounding arrangements combined with a horizontal grounding arrangement;
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the distance between the electrodes is 30 m;
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deepening is at least 0.5 to 0.7 m;
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27 m copper-plated steel electrodes are used as a vertical grounding arrangement (18 pcs x 1.5 m each);
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the copper-plated steel strip with a cross-section 30 x 4 mm, combining all vertical electrodes, is used as a horizontal ground electrode;
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the distance from the grounding arrangement to the machine is not more than 6 m.
Ground terminal resistance calculation:
Vertical electrode resistance:
Верт - Vert
Ом - Ohm
where ρ ρeq – is equivalent soil resistivity, 100 Ohm·m;
L – is vertical electrode length, 27 m;
d – is diameter of the vertical electrode, 0.014 m;
T – is deepening, i.e. the distance from the ground surface to the ground electrode, 14 m;
м - m
where t – is deepening of the electrode top, 0.5 m
Horizontal electrode resistance:
Гор - Hor
Ом - Ohm
where ρ – is soil resistivity, 100 Ohm·m;
b - is horizontal electrode width, 0.03 m;
h - is horizontal electrode depth, 0.5 m;
Lhor – is horizontal electrode length, 120 m..
Electrical impedance of the grounding arrangement:
ЗУ - GA
Ом - Ohm
where n – is a number of sets, vertical grounding arrangements - 5 pcs, horizontal grounding arrangement - 1 pc;
Kutil – is utilization rate, 0.7.
Estimated resistance of the functional grounding arrangement is 0,96 Ohm, which is less than the required value of 1 Ohm.
Design of the grounding arrangement is shown in Fig. 1.
Электрод L=27 м, D=14 мм - Electrode L = 27 m, D = 14 mm
Полоса стальная омедненная сечением 30 х 4 мм - Steel copper-plated bar with cross-section 30 x 4 mm
Figure 1. Equipment layout.
The list of necessary materials is given in Table 1.
Table 1. List of needed materials.
| № | Part number | Name | Quantity, pcs. | Unit weight, kg. | Note |
| FUNCTIONAL GROUNDING: | |||||
| 1. | GL-11075-50 | GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) | 3 | 0,98 | Weight per 1 m |
| 2. | ZZ-001-065 | ZANDZ Copper-plated threaded grounding rod (D14; 1.5 m) | 90 | 2,00 | |
| 3. | ZZ-002-061 | ZANDZ Threaded coupling | 86 | 0,08 | |
| 4. | ZZ-003-061 | ZANDZ Termination | 5 | 0,07 | |
| 5. | ZZ-004-060 | ZANDZ Guide head for jackhammer attachment | 18 | 0,09 | |
| 6. | ZZ-005-064 | ZANDZ Conductor connection terminal (up to 40 mm) | 9 | 0,312 | |
| 7. | ZZ-006-000 | ZANDZ Conductive grease | 9 | 0,10 | |
| 8. | ZZ-007-030 | ZANDZ Waterproofing tape | 3 | 0,40 | |
| 9. | ZZ-008-000 | ZANDZ Attachment to the hammer (SDS max) | 1 | 0,50 | |
Do you need to calculate the functional grounding arrangement for the plasma cutting machine? Please contact the ZANDZ Technical Center!
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