If your facility&#;s priorities involve safety, extending equipment life, or meeting a budget, mastering switchgear preventative maintenance is essential to achieving your goals. This article will guide you through the five most important things to consider for switchgear PM.
Nothing is more important than safety, so knowing how to correctly isolate your equipment is priority number one. Find out if your system has a single source, is double-ended, or if it has tiebreakers. Then, identify potential backfeed issues, either from a generator or someone testing a transformer downstream that is not isolated properly. Make sure you have the proper amount of lockout tagout (LOTO) equipment and never assume your equipment is de-energized; it is crucial that LOTO rules are always followed. Switchgear often has control power coming from other locations and comes
in various voltages (120VAC, 125VDC, 250VDC, etc.).
Knowing what type of environment your equipment is in can guide many of your PM decisions. If the switchgear is dusty, is it from normal, outdoor dust, smoke, or coal dust? Different types of contaminants may require different types and quantities of cleaning products and supplies, like vacuum filters and rags. For example, if you have porcelain insulators, waxing may be necessary (consult the manufacturer for the type needed). If the insulators are epoxy type, lint-free rags and alcohol may be all that&#;s needed.
Some environments have higher chemical vapors, which can quickly corrode metal parts (especially electronic equipment). Make sure that you take pictures to document and pay attention to the physical condition of your equipment. If you find that silver-plated parts are corroding or badly discolored, infrared scans may be needed to ensure that no there are no hotspots developing, which can be a catastrophic failure point.
Know what type of equipment you are going to PM. At a minimum, you should have basic procedures that outline what is needed for each type of equipment to be serviced, such as load break switches, air circuit breakers, vacuum circuit breakers, and motor starters. Also, remember to check for bolt tightness and insulation coverings (cables & bus) as well as inspect surge arresters and instrument transformers. The procedures should include which type of lubrication to be used, where and how to apply the lubrication, test voltages for Hi-Pot and Meggers, relay information for testing both electromechanical and digital relays, torque wrench requirements, and TTR testing details. Find out if the equipment you have uses a specific type or brand of lubrication. In some cases, using the incorrect product will void a warranty or is less effective than the materials the manufacturer used.
Develop a schedule for how often you plan to PM your switchgear. NETA Appendix B lays out a general program to follow for preventative maintenance. It takes into consideration such things as the criticality of equipment, equipment condition, and type of equipment. These are just guidelines, but they provide a great start to developing an effective PM schedule. If you maintain your equipment on a schedule that minimizes the effects of contamination and wear, reliability and uptime will increase and overall cost of ownership will decrease.
Look at the instruction manuals that came with your equipment to see if certain items have specific replacement schedules based on use or age. For obsolete equipment, this can become a challenge. Parts can be very expensive or unavailable, so see if there are retrofits or upgrades that can be done. Southwest Electric Co. can help with locating hard-to-find parts as well as upgrading or retrofitting your equipment. Ignoring these issues will only cost more money and extend any potential downtime.
Lastly, make sure to create comprehensive reports for your switchgear preventative maintenance, and study them closely. This is probably the most overlooked part of an effective PM plan. Most just look at flagged or identified item lists for the &#;found&#; problems. But, if you invest in studying the test reports and trending the results, potential problems can be identified long before failure or service interruption takes place. This saves time by determining if the PM frequency can be adjusted to meet the equipment&#;s real need. Studying reports can also guide you on where to spend (or save) your resources, help you avoid catastrophic equipment failure, and ultimately help keep your personnel from experiencing potentially catastrophic events.
If you are using a third-party testing or a switchgear preventative maintenance company, see if they can format the test reports to make trending easier to follow. Set limits that can be color coded to make identifying negative trends easier to spot.
When optimizing and modernizing your energy management program, switchgear should be an integral part &#; the only question is which type is right for your facilities.
The primary purpose of switchgear is to maintain an uninterrupted power supply to healthy system sections in both low and high-voltage power transformers. It contains individual circuits that distribute power downstream to additional electrical distribution equipment.
It automatically switches off malfunctioning equipment downstream created by system faults to prevent the buildup of abnormal currents that may damage the structure or other connected equipment.
Typical high-voltage switchgear comprises many parts, including fuses, switches, relays, isolators, circuit breakers, lightning arrestors, and indicating devices. All these parts can support a complicated network spanning multiple power stations.
So how does switchgear control, protect, and isolate electrical equipment and circuits? It works by switching electrical currents on and off and isolating circuits to prevent faults and protect equipment and personnel.
When electrical current flows through switchgear, it is controlled by the circuit breakers, disconnect switches, and fuses. When there is an overload or short circuit in the electrical circuit, the circuit breakers trip, interrupting the flow of current and preventing damage to the equipment or personnel.
There are three main switchgear types:
An LV switchgear is a three-phase power distribution unit that can supply electric power at up to 1,000 volts and current up to 6,000 amps. Often used indoors, these are enclosed in a metal case containing copper conductors and a combination of circuit breakers and isolators.
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This type of switchgear is commonly used for distribution systems with voltage above 1 kV up to 36 kV. Depending on the requirement, MV switchgear can come with metal-enclosed indoor or outdoor units. A dedicated MV substation connects to an MV utility distribution network.
A switchgear rated above 36kV AC is a high-voltage switchgear. It is generally classified as gas-insulated indoor-type and air-insulated outdoor-type when used in a high-voltage power system.
A high-voltage switchgear electrical system is more efficient than the typical apparatus. Its efficiency is derived from the high voltage.
The main reason for using a high-voltage switchgear system is enhanced efficiency. When the power is transmitted at a high voltage, the higher voltage results in a lower current required for the same amount of energy to be distributed.
The lower current requires smaller conductors, which are easier to install, less expensive, and more efficient to distribute over longer distances.
LV Switchgear is often used in large facilities as the main incoming distribution if the power requirements exceed A. Located downstream of the main service transformer and typically serving the facility at 480V, this switchgear can include circuit breakers or fuses to protect outgoing circuits.
Digital relays can also be used in this gear for finite control of the protection and allow for the ability to monitor other system conditions beyond overcurrent conditions.
MV Switchgear is located upstream of the transformer, stepping down the requirements to 480V for normal facility use. Typically used in larger facilities where multiple services are incoming from the utility, this switchgear can be looped between one another for redundancy.
HV Switchgear is typically used in utility applications in substations and large campus situations with multiple buildings. HV Switchgear is distributed in a loop system across the campus depending on the use case and then stepped down to MV or LV. In these instances, the circuit breakers would be a vacuum, SF6, etc. breakers or equivalent with relay control or just provided with simple fuse switch protection.
All switchgear has the same common construction a metal frame exterior with copper or aluminum bus bars on the interior that distribute power horizontally across multiple sections, which then connect to vertical bus bars that distribute the individual section protective devices.
Incoming cabling hits the main protective device or stabs off the horizontal bus as the incoming supply. Outgoing cabling will be connected to the individual circuit breaker or fuse circuits to supply loads downstream.
Switchgear was often used only in the MV and HV industries for the past few decades. As power requirements for facilities increased and technology advanced to shrink the footprint of LV Switchgear, it has become more commonly used as a more flexible solution for high-power requirement situations over A to reduce the footprint of gear required.
Besides widespread power station applications, switchgear is used across various commercial and industrial units. For instance, it maintains large motors in a water treatment plant. Construction companies often install switchboards to control power to certain parts of the building site. It is also commonly deployed to serve the hospitality, pharmaceutical, food processing, and consumer goods sectors.
With the rise of electric vehicles and the required charging systems for commercial use and industrial infrastructure for delivery purposes, switchgear for large distribution networks will soon increase the need for both LV and MV.
By , the switchgear market is poised to reach $120.1 billion. The rising cost of electricity, new regulations, and demand for energy-efficient systems drive this demand. As a result, the market is quickly transforming from traditional switchgear systems to digital and intelligent switchgear.
Your organization is likely looking to deploy eco-efficient and high-voltage switchgear systems for smart energy management to save costs. Amid the rising electricity demands, there is little doubt that high-voltage switchgear will play a pivotal role in maximizing efficiency.