The wooden chips workshop is intended to produce process chips from various woods: fir, pine (fir, spruce and silver fir) as well as hardwood (aspen and birch). Then, the production of semi-finished products with high yields is initiated, which is the main raw materials for producing newsprint paper. There are no special requirements to the chips workshop grounding. It is essential to provide the required resistance of a grounding device. The ZANDZ Technical Center has received a request to calculate the grounding system for the chips workshop in Kaliningrad Region. Let us continue with more detailed review of our offered solution.
Calculation of a grounding system for the chips workshop in Kaliningrad Region
Facility: The chips workshop in Kaliningrad Region.
Figure 1. Facility plan.
Task: To perform grounding of a chips workshop in Kaliningrad Region for not more than 10 Ohm.
Solutions to meet the requirements to the chips workshop grounding system in Kaliningrad Region:
A set of measures to ensure the requirements for the grounding arrangement is based on the following solutions:
- a horizontal grounding arrangement made of a zinc-plated steel with cross-section 4 x 40 mm is laid at the depth of 0.7 m along the building perimeter;
- 4 x 6 m vertical electrodes (copper-plated steel rods with the diameter 14 mm) are installed in the corners of the horizontal grounding arrangement;
- vertical and horizontal electrodes are interconnected using clamps ZZ-202-012.
Calculation of equivalent resistance of the grounding arrangement
According to the customer's data, soil: upper layer for 3 m is gravel; lower layer is clay loam.
The gravel resistivity is taken as 5,000 Ohm*m, clay loam is 100 Ohm*m.
Warning! In case the Customer provided erroneous and limited soil data, the above calculation of a grounding arrangement is considered incorrect. If the soil resistivity differs from the calculated one, it is necessary to perform computations with a real value. If the normalized impedance of the grounding arrangement is exceeded, there must be introduced the design corrections.
Equivalent soil resistivity for vertical electrodes
Ом м - Ohm m
Equivalent soil resistivity for horizontal electrodes
Equivalent soil resistivity can be calculated using Table 7.2 from the reference book "Protective Grounding and Electrical Installation Neutral Grounding" by Mankov and Zagranichny.
Таблица 7.2 - Table 7.2
Относительное эквивалентное удельное сопротивление земли ρэг/ρ2 для расчета сопротивления горизонтального электрода - Relative equivalent soil resistivity ρeg/ρ2 to calculate horizontal electrode resistance
Относительное эквивалентное удельное сопротивление при относительной толщине верхнего слоя с учетом глубины заложения электрода - Relative equivalent resistivity at relative thickness of an upper layer based on the electrode depth
Let's calculate the required values:
According to tabular data and using linear interpolation, calculate
Calculation of a grounding arrangement resistance.
The rated resistance of the grounding arrangement is 7.85 Ohm, which is less than the required value 10 Ohm.
Figure 2 shows hardware layout.
Table 1 includes the list of required hardware and materials.
Figure 2. Arrangement of the equipment for the chips workshop grounding in Kaliningrad Region.
Table 1. List of material requirements.
Do you have any questions about grounding of a chips workshop or other facilities? Please, contact the ZANDZ Technical Center!