To fill this need and ensure that used, surplus and reconditioned electrical equipment is as safe as new equipment, electrical suppliers have formed three trade associations; each promulgating technical standards for testing and reconditioning used electrical equipment and installations:
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While EASA and NETA produce standards related to their areas of expertise (motors and field testing and service), this article introduces the 100+ electrical apparatus reconditioning standards PEARL has developed since it's formation in . PEARL's reconditioning standards, now in their fifth revision, give technicians step-by-step best-practice instructions that explain in detail how to inspect, test, recondition, retest and document most common electrical apparatus, including:
Introduction to PEARL Standard Appendices: Section General Information; Section PEARL Calibration Standard; Section Tables
A technical standard is a formal document that establishes uniform engineering or technical criteria, methods, processes and practices. PEARL's Reconditioning Standards define the term "reconditioning" as "the process of returning electrical equipment to safe and reliable operating condition based upon the design of the original manufacturer at the time of manufacturing.' The authority of these standards comes from existing industry standards, including testing and calibration from private organizations and government agencies; original device specifications; and accepted best practices that have been verified by third-party engineering evaluation.
Introduction to PEARL Standard Section , Rev. 5, Low Voltage Disconnect Switches
This section refers to a wide variety of industrial and commercial-duty low-voltage disconnect switches, including load break or non-load break; switchboard, panelboard or wall mount; fused or non-fused disconnects; and electrically closed, electrically opened, both or neither. Low-voltage disconnect switches interrupt or open an electrical circuit, isolating the down stream circuit for purposes of inspection and maintenance. Low-voltage disconnect switches are often used as main disconnecting devices in switchboards and even more frequently used as feeder disconnects. Low-voltage disconnect switches can serve as enclosures for over current protection when they contain fuses. Disconnect switches can also be a part of a ground fault protection scheme when equipped with a shunt trip or a complete ground fault interrupter system that includes: a shunt-trippable disconnect switch, ground fault monitor, sensor and relay.
Introduction to PEARL Standard Section , Revision 5, Low-Voltage Circuit Breakers
Low-voltage circuit breakers covered in PEARL Section Standards include molded case, insulated case and power breakers. Whether using thermal magnetic current sensing and tripping or solid state, they are removed from service and at some point reapplied more than nearly any other type of electrical hardware. The greatest volume of these re-applications is completed with no shop or field testing performed. The need for re-qualification to the extent possible is extreme. While manufacturer product is typically very robust and suitable for reuse under the proper circumstances, performance verification is critical prior to reinstallation.
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Introduction to PEARL Standard Section , Revision 5, Low-Voltage Panelboards, Switchboards and Switchgear
This section of the PEARL Reconditioning standards covers several low-voltage devices, including circuit breaker panelboards, switchboards and switchgear, and motor control centers.
Introduction to PEARL Standard , Revision 5, Low-Voltage Transformers, Dry Type, (600V AC Max. Primary)
Low-voltage transformers covered in PEARL Standards Section include low-voltage dry-type distribution transformers, low-voltage control power transformers, instrument voltage transformers and instrument current transformers.
Introduction to PEARL Standard Section , Revision 5, Low-Voltage Motor Control Center Buckets and Enclosed Assemblies
Elevators, conveyors, pumps, compressors, hoists, blowers, fans and machine tools all rely on electric motors. Manufacturing in particular invests heavily in electric motors. For every motor, there is a control center ' a motor starting device or system.
Introduction to PEARL Standard Section , Revision 5, Low-Voltage Magnetic Starters Open
Magnetic motor starters are a slight misnomer because these devices are responsible for not only starting, but also running, and sometimes staging, an electric motor. 'Staging' refers to the starter assemblies that cause a motor to reverse direction, plug (install), jog (test) or change to another speed. The motor starter also possesses some integral overload protection. The magnetic motor starter is the heart of the control schemes for the magnetic (as opposed to electronic) control of electric motors, whether that control be found in wall mounted enclosure; part of a combination motor starter/circuit protector; part of some sort of reduced voltage starter; or part of a motor control center.
Introduction to PEARL Standard Section , Revision 5, Protection Relays
Protection relays refers to the types of relays referred to in this section, although relays often perform other functions such as sequencing, reclosing, zone interlocking, frequency adjusting and more. Today's relays are so multifunctional and customizable, including Internet connectable, as to make their similarities to earlier relay systems very weak indeed. Today a single relay may displace what used to require ten or more relays in the past. Still, the bulk of what we deal with today is single-function devices that allow specific and accurate control of motor control, circuit breaker or power generator functioning. This section covers only specific protection relays.
Introduction to Proposed PEARL Standard Section Low-Voltage Contactors and Relays
As directional, check and globe valves are to plumbing, contactors and relays are to electrical systems. In this section, we are looking at magnetic control devices for low-voltage circuits. Contactors and relays in these schemes keep low-voltage power, whether line or control voltage, coordinated for control and protective purposes; typically magnetic, these devices allow and disallow the flow of current in a specific fashion and order as determined by the engineers or designers of the system to operate or protect other devices and coordinate their working together.
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Introduction to PEARL Proposed Standard Section Apparatus Accessories and Low-Voltage Surge Arresters
The distribution class surge arrester is the most common type of protective device used on power systems today. Its application typically is limited to systems rated 34.5-kV and lower. The primary function of the distribution surge arrester is to protect the insulation of distribution class oil-filled transformers. Other typical applications include the protection of rotating machines and dry-type transformers. Most common in recent generations of arrestors is the MOV type or Metal Oxide Varistor type. Essentially, this device is installed just ahead of the load and it intercepts major voltage surges that might damage the transformer or motor.
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Introduction to PEARL Standard Section Low-Voltage Bus Duct; Plug-In Disconencts
Bus duct is a 'tubular' distribution system not unlike panel boards or switchboards. These systems have means of separating portions of the available power and routing them to specific locations for use or further redistribution. This is done by plugging in feeder devices, often known as bus plugs. These devices are almost always protective devices but in some cases they are simply means of disconnecting.
Introduction to PEARL Standard Section /, Rev 5, Low-Voltage Bus Duct Plug-In Type; Low-Voltage Bus Duct Feeder Type
As building and plant sizes grow, particularly when there are high currents involved and many circuits to feed along the length and breadth of a facility, it often becomes cost effective to distribute plant power using plug-in bus systems as the primary conductors rather than conduit and wire. Plug-In type allows the bus to be used as a distribution system with disconnect devices installed, or 'plugged-in' throughout the runs. These devices usually include circuit protection by way of fusing or circuit breakers, but not always. These disconnects may feed another distribution system like a panel board or they may feed a single machine.
Introduction to PEARL Standard Section , Revision 5, Medium-Voltage Disconnect Switches
Like low-voltage disconnect switches, medium-voltage disconnect switches perform a number of functions. The term 'disconnect' refers to the act of interrupting or causing an opening in an electrical circuit. In addition to turning off whatever load is consuming this electricity, disconnecting allows for the isolation of the down stream circuit for purposes of inspection and maintenance.
Introduction to PEARL Standard Section , Revision 5, Medium-Voltage Circuit Breakers and Starters
As plants, buildings and electrical loads become larger, the economics of using higher voltages for distribution and for motor control become more compelling. PEARL's Section , Medium-Voltage Circuit Breakers and Starters has both circuit breakers and motor starting contactors.
Introduction to PEARL Standard Section , Revision 5, Medium-Voltage Switchgear
Switchgear is a broad term that covers electrical distribution systems made up of metal clad or metal enclosed cabinets containing switches or circuit breakers. The switches might be fused or non-fused. They might be air break or vacuum break. While manual break devices are the most common, medium-voltage switchgear well could be electrical closed and or opened. Circuit breakers may be air break, oil break or vacuum breaker, even SF6. These will always be electrically closed and opened. Where the breakers or switches are electrically closed, opened or both, there will be a requirement for control power source and control power wiring. The source might be a remote separate source of low voltage brought in from outside the switchgear or it might be provided by transforming line power down to the necessary control voltages. This standard covers the cabinets, bussing, relaying and control circuits only.
Introduction to PEARL Standard , Revision 5, Medium-Voltage Transformers
From the original power source, such as the utility generator, transformers of medium-to-high voltage are used to step up or to step down voltage for the most efficient and cost-effective transmission of electrical energy. They can be found in utility switchyards, on power poles, in shopping centers, schools, manufacturing and process plants, and more. Proper maintenance of this equipment is critical and proper preparation for reapplication is no less critical.
Introduction to PEARL Standard Section , Rev 5, Low-Voltage and Medium-Voltage Fuses
Fuses play a major roll in protection of electrical circuits, loads and operators. Fuses are used to protect against short circuit under extremely high currents, as well as overload. They are suitable for use in the protection of transformers, electric motors, magnetic and solid-state control assemblies, and power distribution runs just to name some of their many applications in industry today.
Introduction to PEARL Standard Sections Low-Voltage Wire and Cable; Medium-Voltage Wire and Cable
Among the various aspects of electrical equipment and supply, you don't get more basic than wire and cable. Wire that has been on the spool a long time may NOT be in the same condition as new and it is absolutely critical that it be examined and tested carefully prior to application.
Introduction to PEARL Standard Sections Metal Conduit, Fittings and Accessories; Non-Metallic Conduit, Fittings and Accessories; Explosion Proof Conduit, Fittings and Accessories; PVC Coated Metal Conduit, Fittings and Accessories
The conduit, fittings and accessories section refer to metal and non-metallic tubing for protecting wire and cable. It includes all of the necessary parts and pieces to route wire from its service source to its final load destination. These parts are necessary to initiate and terminate conduit runs between distribution panels, control boxes and actual load devices such as lights or electric motors, while maintaining the integrity of the protection levels promised by the type of conduit and fittings being used. Standards for reconditioning conduit, fittings and accessories involve cleaning, inspecting and, in some cases, resurfacing. There is no testing other than thread testing.
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