Difference Between Surge Arrester And Lightning Arrester PdfBy Melba V. In and pdf 25.01.2021 at 21:34 3 min read
File Name: difference between surge arrester and lightning arrester .zip
Surge arresters are voltage limiting devices used to protect electrical insulation from voltage spikes in a power system.
- Lightning Arrester
- The Difference Between a Lightning Arrester & Surge Arrester
- What is the difference between Surge Arrester & Lightning Arrester?
Surge arresters are voltage limiting devices used to protect electrical insulation from voltage spikes in a power system. Similar to how a fuse functions to protect an electrical system from damage due to overcurrent conditions, the job of a surge arrester is to protect the system from damage due to overvoltage conditions.
In the past surge arresters were called lightning arresters, this name was based on their primary objective of protecting electrical insulation from lightning strikes on the system.
The more generic term "surge arrester" is now used to encompass overvoltage conditions which can occur from numerous other sources, such as switching operations and ground faults.
Everything from personal computers to HV transmission and distribution systems are susceptible to electrical surges and their destructive effects. A "surge" on an electrical system results from energy being impressed on the system at some point, which can result from lightning strikes or system operations. The impressed energy travels throughout the system in the form of waves, with speed and magnitude that vary along with the parameters of the system.
Photo: Schnider Electric. Each type of surge can affect the surge arrester and insulation system in a different manner.
Lightning results in a fast rate of rise because it's a true source of coulomb energy, while switching operations result in a relatively slow rate of rise because it's energy is stored in the magnetic fields of the system. Along with surge phenomena, a system can also experience a longer term overvoltage from electrical faults.
Depending on the configuration and grounding of the system, a single line-to-ground fault will cause system voltage on the unaffected phases to escalate. Per the National Electrical Code NEC , a surge arrester is defined as: "A protective device for limiting surge voltages by discharging or bypassing surge current, and it also prevents the flow of follow current while remaining capable of repeating these functions".
The original lightning arrester was nothing more than a spark air gap with one side connected to a line conductor and the other side connected to earth ground. When the line-to-ground voltage reached the spark-over level, the voltage surge would be discharged to earth ground. Older surge arresters generally consist of silicon carbide resistor blocks in series with air gaps, these arresters normally carry no current and have a single voltage rating.
Aside from a few exceptions, selection of these arresters is fairly simple:. For solidly grounded systems, the next higher arrester rating above the system line-to-neutral voltage is used. For resistance grounded or ungrounded systems, the next higher rating above the system line-to-line voltage is used. Metal oxide surge arresters contain blocks of a variable resistance material, usually zinc oxide, with no air gaps.
Line-to-ground voltage is applied continuously between the line and ground terminals of the arrester, these arresters do carry a minimal leakage current which can be withstood on a continuing basis. When surges occur, the arrester immediately limits, or clamps, the overvoltage condition by conducting the surge current to ground. After passage of the surge, the arrester returns to its initial state.
The surge arrester minimal leakage current is primarily capacitive, with a small resistive component. Metal oxide has many advantages as a surge protector, but it is somewhat more complicated than older surge arresters to apply correctly.
Instead of a single voltage rating, metal oxide surge arresters have three ratings:. The class of surge arrester to be applied on a system depends upon the importance and value of the protected equipment, the impulse insulation level, and the expected discharge currents the arrester must withstand.
The primary objective in arrester application is to select the lowest rated surge arrester that will provide adequate protection of the equipment insulation and be rated such that it will have a satisfactory service life when connected to the power system. The best location for installation of a surge arrester is as close as possible to the equipment its protecting, preferably at the terminals where the service is connected to the equipment. It is important that surge arresters of the correct voltage rating be used.
Both issues of arrester service life and equipment protection should considered when selecting surge arresters. If different ratings are required, the highest resulting surge arrester rating should be chosen. Arrester nominal ratings for various utilization system voltages line-to-line are based on the system's grounding configuration. Choosing the correct arrester rating is critical to prevent an application where the arrester can potentially have a violent failure.
Any system other than a solidly grounded configuration is considered to be effectively ungrounded and a higher arrester rating should be chosen. Arresters are continually exposed to the power system operating voltage during normal operation. For each arrester rating, there is a recommended limit to the magnitude of voltage that may be applied continuously. The arrester rating is selected so that the maximum continuous power system voltage applied to the arrester is less than, or equal to, the arrester's MCOV rating.
Both the circuit configuration wye or delta and arrester connection Line-to-Ground or Line-to-Line are taken into consideration. This is a key factor in the selection and application of an arrester. If the system grounding configuration is unknown, assume the system is ungrounded. Photo: General Electric. The continuous operating voltage is 13, divided by the square root of 3, or V. Depending on the magnitude and duration of system overvoltages, it may be necessary to use a 10 kV arrester with an MCOV of 8.
Depending on the time needed for protective relays to clear ground faults off the system, the choice will be between arresters rated 12 kV, 15 kV and 18 kV. The Temporary overvoltages can be caused by numerous system events, such as switching surges, line-to-ground faults, load rejection and ferroresonance. The system configuration and operating practices are evaluated to identify the forms and causes of TOV. The primary effect of temporary overvoltages on metal-oxide arresters is the increased current, power dissipation, and increased arrester temperature.
These conditions affect the protection and survivability characteristics of the arrester. The surge arrester's TOV capability must meet or exceed the expected temporary overvoltages of the system. Surge arresters are selected in coordination with standard electrical equipment insulation levels so that they will protect the insulation against over voltages.
This coordination is based on selecing an arrester that will discharge at a lower voltage level than the impulse voltage required to break down the insulation. Most electrical equipment is rated for impulse levels as defined by industry standards. The Basic Impulse Insulation Level BIL of equipment is determined by applying a full-wave voltage surge of a specified crest value to the equipment insulation, this is known as the Impulse Test.
If the service capability of a surge arrester is exceeded, the metal-oxide disk s may crack or puncture, reducing the arrester's internal electrical resistance. This reduction of resistance will limit the arrester's ability to withstand future overvoltages but it will not jeopardize the insulation properties of the arrester. In the event that an arrester fails, a line-ground arc will develop and pressure will build up inside the arrester housing.
The pressure is safely vented to the outside and an external arc will be established, maintaining equipment protection. Once an arrester has safely vented, it's no longer capable of pressure relief and should be replaced immediately.
To help ensure maximum service life and reduce the chances of sudden failure, surge arresters should be maintained and electrically tested at regular intervals. Inspection and testing should also be performed as part of new installations prior to commissioning.
Field testing of surge arresters can help extend service life and reduce the chances of sudden failure. A comprehensive outline for testing surge arresters is described below. Only qualified workers with the proper safety training and calibrated testing equipment should perform these tasks. The physical and mechanical condition of the surge arrester should be evaluated before any testing is performed.
For new installations, compare the arrester nameplate data with project drawings and specifications. Inspect the arrester housing, mounting, alignment, grounding, and required clearances.
Surge arresters should be clean and free of obstructions to minimize contaminates that may lead to tracking or be harmful to the arresters insulating properties. Prior to cleaning the unit, perform as-found tests to compare results.
Photo: Paul Chernikhowsky via Flickr. Lead length for the connection of the surge arrester to the equipment terminals and to ground should be minimized and installed as straight, minimizing bends in the leads, as possible.
Increases in the lead length will reduce the protection capabilities of the surge arrester, due to the additional increase of impedance in the lead. Bolted electrical connections should be inspected for high resistance by using a low-resistance ohmmeter. Compare the measured resistance values to the values of similar connections. Values which deviate from those of similar bolted connections by more than 50 percent of the lowest value should be investigated.
Tightness of accessible bolted electrical connections may also be verified by using a calibrated torque wrench in accordance with manufacturer's published data or NETA Table Verify that each surge arrester ground lead is individually attached to a ground bus or ground electrode. Point-to-point tests can be performed to determine the resistance between the main grounding system and individual arrester ground points. The resistance between the surge arrester ground terminal and the ground system should be less than 0.
Perform insulation-resistance tests on each arrester, phase terminal-to-ground. Apply voltage in accordance with manufacturer's literature. The measurement of dielectric loss is effective in detecting defective, contaminated, and deteriorated arresters. Watts loss values are evaluated on a comparison basis with similar units and test equipment manufacturer's published data.
Arrester assemblies consisting of single units per phase are generally tested by the grounded-specimen test method GST. All arresters should be tested individually and not in parallel. The watt-loss test is an optional test per NETA acceptance and maintenance testing standards. Stroke counters measure lightning strikes by the induction of current and do not require the use of any external power source. Verify that stroke counter, if present, is correctly mounted and electrically connected.
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The Difference Between a Lightning Arrester & Surge Arrester
Surge arrester is used to protect the circuit or electrical equipment from high voltage transient or electrical surges. It may damage the electrical equipment. In order to avoid this, the surge arresters are normally used. Lightning arrester works like surge arrester from outside of the conductor. They absorb the electrical surges in the transmission tower itself. Lightning rod is a pre protection device.
Surge arrester protects the system from lightning, switching, electrical faults and other transients voltage and surges while lightning arrester are mainly used for lightning strikes and associated surges. Surge arrester can be used as a lighting arrester while lighting arrester can't be used as a surge arrester.
What is the difference between Surge Arrester & Lightning Arrester?
Register now or log in to join your professional community. So Lighting Arrestor is related to only Lighting. It is also used at top of the Buildings. Products By Bayt.
State the difference between Surge Arrester and Lightning arrester,Both are same or not? Surge Arresters are widely also known Lightning arresters. However strictly speaking the two are in fact different.
What is the Difference Between a Lightning Arrester and a Surge Arrester?
Different terms used for arresters are sometimes confusing even professional engineers and electricians use them interchangeably. We will discuss the main difference between the different types of arresters such as surge arrester, lightning arrester, surge suppressor and lighting rod as sometimes, they may used for same purpose. The difference shows that what kind of system you want to protect from what and how? We will discuss all of them in details below. Surge arrester is a voltage limiting device installed inside the installation equipment panel to protect the insulation, equipment and machines not only from lightning, but also from transient voltage produced by switching, sparks, load shading and other electrical faults such as ground faults etc. Surge arresters are used to limit the current and voltage surges to protect the low and high voltage appliances as well as communication lines.
A surge arrester is a protective device for limiting voltage on equipment by discharging or bypassing surge current. It prevents continued flow to follow current to ground and it is capable of repeating these functions as specified per ANSI standard C An arrester does not absorb lightning or stop lightning.