Test, Maintenance And Controls For Lightning Protection Systems
Data Base / Frequently Asked Questions
Lightning Protection Systems should be checked regularly by authorized technical personnel in certain periods.
Related documents such as National and / or International Technical and Occupational Safety Standards and Fire Regulations also contain some sanctions and instructions regarding the Lightning Protection System.
According to this;
1. There must be a file of the Lightning Protection System (as a printed document and / or in the virtual medium) in the building / facility.
(a) "Coverage Area Project" calculated according to the Lightning Protection Level (LPL) of the system,
(b) National and / or international documents (obtained from accredited institutions abroad) of all products used in the system (taken from TSE and accredited institutions),
(c) Warranty Documents of the Products,
(d) Test Reports showing the measurements of the Grounding System,
(e) Activation Test Reports if Active Lightning Rod is Used in the Installation,
(f) "Lightning Counter" records should be kept in the installation,
(g)… and there should be documents for other hardware.
2. Electricity systems in a building should be measured, maintained and controlled regularly,
3. Lightning Protection Systems;
(a) Measurement of ground transition resistances from the Test / Measurement Point of the Earth Termination (Grounding) Systems,
(b) Controls of surge arresters used as internal lightning arrestors,
(c) Controls of Air Terminal (Capture End) and Down conductors,
(d) If Active Lightning Rod is used in the installation, the controls of the Activation Tests,
(e) In addition, if any, additional systems such as Obstacle Lights and Warning equipment should be operated. Information about the maintenance periods of these controls is given in the table below.
Lightning Protection System should be inspected at least once a year. (TS EN 62305-3)
In cases of severe weather changes and extreme thunderstorms/thunderstorms, the system should be inspected regardless of the periodic maintenance schedule.
If there is a Lightning Counter/Counter (*) in the installation, it should be determined whether the installation has received a lightning strike by comparing it with the previous records, and if the installation has received a lightning strike, the entire installation must be reviewed as soon as possible.
(*) The Lightning Counter is a product that counts the lightning strikes falling on the installation. LİVA GROUP recommends using Yıldırım Counter for tracking statistical information.
GROUNDING MEASUREMENTS:
In electrical and electronic systems, especially in circuits where fault currents are carried from the ground surface and in lightning protection systems, low grounding resistance is very important for the healthy and reliable operation of the systems.
The low ground resistance is directly related to the soil structure and the electrode and grounding conductor used in practice. Therefore, for a good (low) grounding resistance, in the area where earthing will be made;
1. The appropriate region and soil structure should be selected, and materials that increase the conductivity of the soil texture (*) should be used in places where the soil structure is not suitable,
(*) Liva Soil Conductivity Material (TIM) is used to increase the conductivity of the soil and you can find more detailed information about TIM in the following pages.
2. Earthing electrodes and conductors with appropriate cross-section and standards should be used,
3. The grounding electrode and grounding conductor should be well connected. For trouble-free cable joints, Thermowelded Joint Method (**) is used today.
(**) Liva Thermowelding Powder offers many different and various solutions for Electrode-Cable joints. By using Thermowelding Powder and other additional accessories, cable joints and Additional Material are used to increase the conductivity of the soil and you can find more detailed information about TIM in the following pages.
In order to choose the most suitable region in the grounding field, the "Soil Specific Resistance (Soil Resistivity)" should be measured from different points and the most suitable area should be used as the grounding field.
Earthing Specific Resistance (ρ);
Soil Specific Resistance It is the electrical resistivity of the soil that changes depending on the type, humidity and temperature of the soil.
The soil resistivity is the resistance of a cube with one (1) meter side and its unit is ohm.mm² / m = ohm.meter. In other words, the Soil Specific Resistance value is expressed as Ohm Meter (Ω.m).
With measurement, you have information about how the soil transmits electrical currents. The lower the specific resistance, the lower the value of the grounding resistance value (i.e. positive for the system). This reduces the amount of ground electrode and other equipment needed and the project cost.
Soil specific resistance varies according to the region and soil type. Humidity and temperature affect this resistance. Accordingly, it increases frost or drought resistance. Therefore, soil resistivity varies according to the season or the measurement moment.
Since temperature and humidity levels will be more stable as you go underground, deeper measurements should be made to avoid seasonal effects.
The Soil Specific Resistance must be determined to be used in the grounding calculations of the entire system during the electrical project phase of the building / facility.
By determining the soil specific resistance;
1. Grounding type and electrode selection can be made at the project stage of the buildings / facilities.
2. Ground electrode and soil system technical properties can be written.
3. Grounding system costs to be used for the system can be optimized by determining the ground resistance.
Therefore, as a result, this measurement provides important information regarding the selection and positioning of grounding electrodes in large construction sites or in factory / step down centers.
Soil Specific Resistance Measurement;
Many calculation methods can be used to determine the soil resistivity. The most commonly used methods in practice are four (4) reference electrodes that can be measured;
A. Wenner Method (Suitable for a constant depth),
It is the B. Schlumberger Method. (Suitable for different depths)
A. Wenner Method: It is the most common measurement method used.
Measurement Principle; The measurement is performed by placing four (4) reference electrodes in a line on the ground with (a) equal distance.
With the tester, the "I" current is applied between the electrodes "E" and "H". The voltage value "ΔV" between the "ES" and "S" electrodes is measured.
The resistance value R read on the ohmmeter is used in calculating the specific resistance.
Accordingly, Specific Resistance (ρ)
Here (ρ) (in .m) represents the specific resistance under point 0 h = 3/4 a depth.
The value (a) represents the distance between the reference electrodes (meter, m), the value (R) represents the resistance (ohm, Ω) measured by the device.
Note: The shortest recommended distance for measurement is 4 meters.
B. Schlumberger Method: The Schlumber method works with the same principle as the Wenner method.
Measurement Principle; The difference with the Wenner Method is only the difference in the placement of the reference electrodes.
The Specific Resistance is calculated using the distance (2d) between the outer two reference electrodes, the distance between the inner two reference electrodes (a) (meter, m), and the resistance value (R) (ohm, Ω) obtained as a result of the measurement in the following formula.
Accordingly, Specific Resistance (ρ);
Since this method can only be measured by moving the outer two reference electrodes, it saves considerable time, especially in large field resistivity measurements.
Earthing (Through) Resistance (R);
Grounding Systems are important systems for the application, operation and continuity of all electrical circuits;
A. Ensuring the connection of operating circuits of transformers and panels with ground,
B.Transmission of fault currents that may occur as a result of breakdown / puncture and / or damage of the insulation structure of panels, devices and machines to the ground in the fastest way without creating vital risks for living things,
A. These are the systems designed to ensure the connection of special systems / circuits such as lightning rods and surge arresters with the ground.
In this context, ground connection is made by using different techniques and different grounding electrodes according to the structure of the circuit.
Since the grounding system is not suitable, it creates the risk of serious loss of life and property, so the system should be measured and checked in certain periods within the scope of national and international standards, and if it does not comply with the standards, it must be improved and / or renewed.
Generally, two different methods are used for the measurements of the Grounding System. These;
1. Three-End (Using Two Reference Electrodes) Comparison Measurement Method,
2. Loop Impedance (Over Phase, Neutral and Earth Line) Measurement Method. For both measurements, a measuring instrument suitable for the features that can make these measurements should be used.
According to this;
1. Three-End Comparison Measurement Method: The measurement tool and connection details for the measurement of the Ground (Transition) Resistance with the Three-End (Using Two Reference Electrodes) Comparison Method are given below.
When measuring with a three-prong measuring device, two (2) 20-25 cm long reference electrodes (with a T-shaped tip pointed to allow easy entry into the soil) and three (3) test cables (with tongs / sockets with different color and length tips) are used.
The grounding system to be measured is separated from the network / line to which it is connected by using earthing busbar and / or test terminal.
For the measurement, the grounding system electrodes (Rx) and the reference electrodes are driven into the ground at a distance of 5-10 meters each. (For a healthy measurement, the surface should not be filled with soil.)
The grounding system to be measured and the reference electrodes are connected with the appropriate socket of the measuring instrument with test cables.
Measurement is carried out in steps specified in the test device user manual.
2. Loop Impedance Measurement Method: The measurement instrument and connection details for the measurement of the Ground (Transition) Resistance with the Loop Impedance (Over Phase, Neutral and Ground Line) Measurement Method are given below.
Accordingly, the grounding resistance can be measured without using reference electrodes at every point with Phase and Neutral lines.
While measuring with the Loop Impedance Measurement Method, three (3) test cables (with tongs / sockets at the ends of different colors and lengths) are used.
Phase and Neutral line is connected to the appropriate socket of the measuring instrument via the grounding system to be measured and the Electric Panel / Electric Bus Bar or Socket.
Measurement is carried out in steps specified in the test device user manual.
Soil resistance can be measured easily with this method, especially in areas where the soil surface cannot be found and in high-rise and / or underground structures / facilities.
Today, measuring instruments that can be directly attached to socket lines are also used in order to make more practical and fast measurements.
Within the scope of all this information, Soil Specific Resistance (Resistivity) and Grounding Resistance measurements must be measured and recorded at the appropriate time and / or at appropriate periods during the project, installation and maintenance stages of the Grounding Systems.