Publish Time: 2025-12-16 Origin: Site
Surge arresters are used to guard electrical systems against surges due to lightning arcs or switching procedures. Nevertheless, failure may occur if they are not connected properly. Understanding how to connect a surge arrester can guarantee safety and reliable operation.
In this guide, we'll show you how to install and connect surge arresters for optimal performance.
A surge arrester is a protective device that diverts excess current safely to the ground when a surge occurs.
It is important to properly connect a surge arrester since this defines the effectiveness of the surge arrester in undertaking its protective role.
Here are the components involved in connecting a surge arrester and their respective functions:
Surge arrester body: It is the main protective unit, which has zinc oxide blocks that take in and release surge energy.
Line terminal: The line terminal is the part that carries a source voltage. It is normally related to the line conductor.
Ground terminal: The ground terminal is the part that holds excess current and helps to safely take the current to the ground or earth. It is normally related to the grounding system.
Connecting conductors: These are conducting wires that connect the system and the ground to the arrester.
Grounding rod: The grounding rod gives a low-resistance pathway through which the surge current can be dispelled into the ground.
Mounting hardware: The mounting hardware consists of brackets and insulators that secure the arrester.
The right location to install a surge arrester can help identify how well it would protect the electrical system.
Place arresters at the line terminals of distribution transformers so that they intercept overvoltages before they reach sensitive equipment. In low-voltage installations, mount arresters at the service entrance so that they protect sensitive electronics.
To ensure overhead distribution, install arresters close to poles or at an entry point of the line in order to minimize the distance over which the surge energy passes. Install surge arresters near busbars in substations to prevent damage from surge events.
More so, take into consideration the physical layout. Select a point at which the length of conduit to the grounding system and equipment to be safeguarded is as short as possible. Evaluate environmental exposure. Install external arresters in areas that are not prone to environmental degradation. Make sure that the arrester matches fusing, circuit breakers, or reclosers.
The second thing is to ensure the voltage rating and suitability of the arrester with the equipment it is guarding. Surge arresters are optimized to a given nominal system voltage, and they have such parameters as maximum continuous operating voltage (MCOV), rated voltage, and impulse withstand capability, which must be appropriate to the equipment.
A surge arrester should not be connected to a surge rating that is lower than the surge arrester itself. Conversely, an arrester that has unsuitable protective characteristics can fail to effectively clamp the surges on the equipment insulation level. Check the arrester's parameters against the expected surge environment for the site.
Determine whether the application is a low-voltage, medium-voltage, or high-voltage arrester. Place low-voltage arresters at service entrances and distribution panels. Install high-voltage arresters at transformers, switchgear, and transmission lines.
Consider the insulation coordination of the equipment and ensure it aligns with the arreter's protective level to prevent flashovers. Check environmental ratings, mechanical strength, and arrester type.
Select mounting hardware for the weight and mechanical loads of the arrester, such as wind or conductor tension. In the case of structure-mounted arresters, corrosion-resistant brackets and stainless steel fasteners should be utilized, so that no rusting or corroding takes place. Secure the mounting location to maintain the clearances of the manufacturer with respect to live parts and equipment.
If the arrester is mounted on a base or insulator, connect it as required by the manufacturer to ensure that the creepage distance is maintained, as well as to avoid the decrease in dielectric strength in the presence of pollution.
The arrester should be in a vertical position to allow the drainage system and avoid the pooling of water around terminals. Install insulating supports to ensure that there are the necessary distances between the conductors of phases and grounded structures.
When the arresters are mounted in a group, keep a sufficient distance so that the arresters do not overheat. Do not exert excessive force on terminals when fitting between the terminals on transformer bushings. Tighten the bolts according to the recommended screw torque values. Support the arrester body in such a way that no stress is put on the electrical connections.
Next, connect the line terminal properly so that the arrester can intercept surges immediately. Choose a conductor size that supports the thermal and short circuit requirements of the system. Install compression fittings that can align with the design of the terminal on the arrester and make the contact surfaces remain clean and free from contamination.
In case of aluminum conductors, an approved anti-oxidation compound as given by the manufacturer should be used. Check the terminal threads to make sure it is not damaged, and then connect. Install bolted connectors to the correct torque given by the manufacturer. A loose contact may enhance resistance and overheating
In a busbar connection, ensure that the seating is smooth and that there is no insulation clearance. After tightening, check the line terminal and the source conductor to ensure that there is a solid path. Replace protective terminal covers to prevent accidental contact and moisture buildup.
Choose a grounding conductor that is large enough in terms of cross-sectional area and mechanical strength. You are advised to use a short conductor of copper as recommended by the manufacturer or local requirements. Connect the ground contact with heavy-duty compression.
When connecting the ground conductor, keep it straight and short. Connect it to a dedicated grounding grid. When connecting to an existing grounding system, make sure that the point of connection has a low impedance and meets the requirements.
Protect connections against corrosion and secure grounding points from mechanical damage.
After connecting the ground terminal, the next step is to ensure that the ground resistance is checked. Test the resistance between the arrester ground connection and the facility grounding system with the necessary equipment, which is a calibration of an earth resistance tester.
In commercial settings, effective dissipation is suggested to be less than 5 ohms against the target resistance. The value, however, varies depending on the site conditions, the voltage level of the system, and the safety standards. Select the right testing method in order to achieve the correct readings.
In the case of the fall-of-potential technique, install probes at the recommended distances and measure at several points in order to determine localized high-resistance zones. If the resistance is too high, use corrective measures to reduce the resistivity.
Conduct continuity tests between the arrester ground and the remaining bonding systems. Record the measurements and retest after each corrective action. Have a schedule of periodic monitoring of grounding resistance and retest after major surge events or earthworks.
The last step is to check and test that the surge arrester is installed correctly and ready to work when needed. Start with a visual inspection of the mechanical and electrical connections. Look for loose bolts, corrosion, contamination, discoloration, or any other physical damage to the arrester housing and terminals. Make sure the torque values match those from the inspection, and tighten any loose connections.
Check the condition of the insulation bases and protective covers to keep out moisture and prevent accidental contact. Perform electrical tests on the line and ground conductors, and measure insulation resistance. Verify the communication link in arresters with monitoring features. Ensure the alarm thresholds are set correctly in the protection system.
If the arrester has a replaceable fuse link, check its status and record the readings. Carry out diagnostic tests to ensure it's ready to operate. Finally, create a detailed report of the completed installation. Train personnel on safety and emergency procedures after a surge event.
Using the wrong size of grounding wire can compromise the arrester's performance. For example, a thin or long grounding conductor can increase resistance. Use copper or aluminum conductors that are short to help with the quick discharge of currents into the earth.
Do not connect a surge arrester in series; always connect them in parallel. A series connection can cause a fault current and prevent normal functioning, which can harm both the arrester and the circuit. In contrast, a parallel connection safely releases excess current without affecting power continuity and the system.
Poor earthing or high-resistance earthing can lead to arrester failure. Having a ground that exceeds the recommended limits (typically 5 ohms) decreases the discharge capability of the arrester. It is always a good idea to test and maintain a reliable grounding system with multiple rods or grids to create a low-resistance path.
If you install an arrester with a voltage rating lower than the system's nominal voltage, you may face continuous leakage and breakdown. Connecting an arrester with a higher voltage rating than the system's voltage may affect its ability to protect equipment. So, before connecting, make sure the rated voltage matches the MCOV of the arrester to the system unit.
Long or sharply bent conductors can increase inductance and delay surge discharge. Ensure that the path between the line, arrester, and ground is short and straight. Do not connect surge protection between conductors near metallic objects, as this can reduce the effectiveness of the protection.
Do not forget to perform post-inspection. Check for loose connections and address any issues.
You've gotten to the end of the article. By now, you should understand how to connect a surge arrester. You've also learnt that every connection must be secure, properly rated, and well-tested for safety and reliable protection.
For durable surge arresters and connection guidance, choose Haivol Electrical. Contact us today for professional support and personalized recommendations.
The installation process of a surge arrester is straightforward. First, turn off the power, mount the arrester near the main electrical panel, and connect the line terminal and the ground terminal. Next, reassemble the panel and verify the insulation. Follow the manufacturer's instructions, use the correct tool, and ensure the arrester is grounded correctly. Confirm its working status, and you're good to go.
No, you cannot install a surge arrester by yourself. Doing so can lead to errors, injury, and potential damage. Even if you know how to install, it is recommended that you hire a licensed electrician to ensure it is properly installed and complies with safety codes.
A surge arrester protects equipment against overvoltages from internal events like switching surges, and external events like lightning. A lightning arrester, on the other hand, is specifically designed to handle surges that come from direct lightning strikes.
The correct way to connect a surge arrester to a transformer is to attach it as close as possible to the high-voltage and low-voltage terminals of the transformer. Connect it directly to the transformer's grounding system with a short conductor to ensure fast surge discharge.
To test if a surge arrester is properly connected, conduct a visual inspection, check for status lights, and use a multimeter for basic verification. For high-risk applications, it is recommended that you get the help of a professional for safety reasons.
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