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41-423: For example, a subway map intended for passengers may represent a subway station with a dot. The dot is not intended to resemble the actual station at all but aims to give the viewer information without unnecessary visual clutter. A schematic diagram of a chemical process uses symbols in place of detailed representations of the vessels, piping, valves, pumps, and other equipment that compose the system, thus emphasizing

82-531: A wiring diagram , which preserves the spatial relationships between each of its components. Schematics and other types of diagrams, e.g., A semi-schematic diagram combines some of the abstraction of a purely schematic diagram with other elements displayed as realistically as possible, for various reasons. It is a compromise between a purely abstract diagram (e.g. the schematic of the Washington Metro) and an exclusively realistic representation (e.g.

123-441: A copy machine). As such, the modern practice for representing a 4-way wire connection is to draw a straight wire and then to draw the other wires staggered along it with "dots" as connections (see diagram), so as to form two separate T-junctions that brook no confusion and are clearly not a crossover. For crossing wires that are insulated from one another, a small semi-circle symbol is commonly used to show one wire "jumping over"

164-416: A descriptor or reference designator matching that on the list of parts. For example, C1 is the first capacitor , L1 is the first inductor , Q1 is the first transistor , and R1 is the first resistor . Often the value or type designation of the component is given on the diagram beside the part, but detailed specifications would go on the parts list. Detailed rules for reference designations are provided in

205-425: A failure. Maintenance functions can be defined as maintenance, repair and overhaul ( MRO ), and MRO is also used for maintenance, repair and operations . Over time, the terminology of maintenance and MRO has begun to become standardized. The United States Department of Defense uses the following definitions: Maintenance is strictly connected to the utilization stage of the product or technical system, in which

246-431: A metal film. The internationally standardized symbol for a resistor is therefore now simplified to an oblong, sometimes with the value in ohms written inside, instead of the zig-zag symbol. A less common symbol is simply a series of peaks on one side of the line representing the conductor, rather than back-and-forth. The linkages between leads were once simple crossings of lines. With the arrival of computerized drafting,

287-403: A predicted/fixed shelf life schedule. These items are given to tax-exempt institutions. Condition-based maintenance ( CBM ), shortly described, is maintenance when need arises . Albeit chronologically much older, It is considered one section or practice inside the broader and newer predictive maintenance field, where new AI technologies and connectivity abilities are put to action and where

328-455: A significant number of pages to schematic diagrams. Circuit diagram A circuit diagram (or: wiring diagram, electrical diagram, elementary diagram, electronic schematic) is a graphical representation of an electrical circuit . A pictorial circuit diagram uses simple images of components, while a schematic diagram shows the components and interconnections of the circuit using standardized symbolic representations. The presentation of

369-534: A vertical power supply rail on the left and another on the right, and components strung between them like the rungs of a ladder. Once the schematic has been made, it is converted into a layout that can be fabricated onto a printed circuit board (PCB). Schematic-driven layout starts with the process of schematic capture . The result is what is known as a rat's nest . The rat's nest is a jumble of wires (lines) criss-crossing each other to their destination nodes. These wires are routed either manually or automatically by

410-487: Is any variety of scheduled maintenance to an object or item of equipment. Specifically, planned maintenance is a scheduled service visit carried out by a competent and suitable agent, to ensure that an item of equipment is operating correctly and to therefore avoid any unscheduled breakdown and downtime. The key factor as to when and why this work is being done is timing, and involves a service, resource or facility being unavailable. By contrast, condition-based maintenance

451-641: Is not directly based on equipment age. Planned maintenance is preplanned, and can be date-based, based on equipment running hours, or on distance travelled. Parts that have scheduled maintenance at fixed intervals, usually due to wearout or a fixed shelf life , are sometimes known as time-change interval, or TCI items. Predictive maintenance techniques are designed to help determine the condition of in-service equipment in order to estimate when maintenance should be performed. This approach promises cost savings over routine or time-based preventive maintenance , because tasks are performed only when warranted. Thus, it

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492-532: Is not lubricated on schedule" that functions "until a bearing burns out." Preventive maintenance contracts are generally a fixed cost, whereas improper maintenance introduces a variable cost: replacement of major equipment. Main objective of PM are: Preventive maintenance or preventative maintenance ( PM ) has the following meanings: Other terms and abbreviations related to PM are: Planned preventive maintenance (PPM), more commonly referred to as simply planned maintenance ( PM ) or scheduled maintenance ,

533-423: Is not trivial to turn this measured data into actionable knowledge about the health of the equipment. As systems get more costly, and instrumentation and information systems tend to become cheaper and more reliable, CBM becomes an important tool for running a plant or factory in an optimal manner. Better operations will lead to lower production cost and lower use of resources. And lower use of resources may be one of

574-782: Is often used. In electronic design automation, until the 1980s schematics were virtually the only formal representation for circuits. More recently, with the progress of computer technology, other representations were introduced and specialized computer languages were developed, since with the explosive growth of the complexity of electronic circuits, traditional schematics are becoming less practical. For example, hardware description languages are indispensable for modern digital circuit design. Schematics for electronic circuits are prepared by designers using EDA ( electronic design automation ) tools called schematic capture tools or schematic entry tools. These tools go beyond simple drawing of devices and connections. Usually they are integrated into

615-456: Is regarded as condition-based maintenance carried out as suggested by estimations of the degradation state of an item. The main promise of predictive maintenance is to allow convenient scheduling of corrective maintenance , and to prevent unexpected equipment failures. This maintenance strategy uses sensors to monitor key parameters within a machine or system, and uses this data in conjunction with analysed historical trends to continuously evaluate

656-557: Is that the first generation of CBM in the oil and gas industry has only focused on vibration in heavy rotating equipment. Secondly, introducing CBM will invoke a major change in how maintenance is performed, and potentially to the whole maintenance organization in a company. Organizational changes are in general difficult. Also, the technical side of it is not always as simple. Even if some types of equipment can easily be observed by measuring simple values such as vibration (displacement, velocity or acceleration), temperature or pressure, it

697-532: The International standard IEC 61346 . It is a usual (although not universal) convention that schematic drawings are organized on the page from left to right and top to bottom in the same sequence as the flow of the main signal or power path. For example, a schematic for a radio receiver might start with the antenna input at the left of the page and end with the loudspeaker at the right. Positive power supply connections for each stage would be shown towards

738-497: The acronym CBM is more often used to describe 'condition Based Monitoring' rather than the maintenance itself. CBM maintenance is performed after one or more indicators show that equipment is going to fail or that equipment performance is deteriorating. This concept is applicable to mission-critical systems that incorporate active redundancy and fault reporting . It is also applicable to non-mission critical systems that lack redundancy and fault reporting. Condition-based maintenance

779-431: The concept of maintainability must be included. In this scenario, maintainability is considered as the ability of an item, under stated conditions of use, to be retained in or restored to a state in which it can perform its required functions, using prescribed procedures and resources. In some domains like aircraft maintenance , terms maintenance, repair and overhaul also include inspection, rebuilding, alteration and

820-436: The connection of two intersecting wires was shown by a crossing of wires with a "dot" or "blob" to indicate a connection. At the same time, the crossover was simplified to be the same crossing, but without a "dot". However, there was a danger of confusing the wires that were connected and not connected in this manner, if the dot was drawn too small or accidentally omitted (e.g. the "dot" could disappear after several passes through

861-452: The corresponding aerial view of Washington). In electrical and electronic industry, a schematic diagram is often used to describe the design of equipment. Schematic diagrams are often used for the maintenance and repair of electronic and electromechanical systems. While schematics were traditionally drawn by hand, using standardized templates or pre-printed adhesive symbols, today electronic design automation software (EDA or "electrical CAD")

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902-481: The design ( circuit design ), construction (such as PCB layout), and maintenance of electrical and electronic equipment. In computer science , circuit diagrams are useful when visualizing expressions using Boolean algebra . Circuit diagrams are pictures with symbols that have differed from country to country and have changed over time, but are now to a large extent internationally standardized. Simple components often had symbols intended to represent some feature of

943-494: The details that would be repeated on each phase of a three-phase system, showing only one element instead of three. Electrical diagrams for switchgear often have common device functions designate by standard function numbers . Another type of diagram used for power systems is a three-line diagram . For analysis purposes of a power system, from the one-line diagram, if the system is balanced, an equivalent per-phase (or single-phase ) schematic diagram can be obtained. If all of

984-450: The drawing. Detailed rules for the preparation of circuit diagrams, and other document types used in electrotechnology, are provided in the international standard IEC 61082-1 . Circuit diagrams are often drawn with the same standardized title block and frame as other engineering drawings . Relay logic line diagrams, also called ladder logic diagrams, use another common standardized convention for organizing schematic drawings, with

1025-410: The functions of the individual elements and the interconnections among them and suppresses their physical details. In an electronic circuit diagram , the layout of the symbols may not look anything like the circuit as it appears in the physical world: instead of representing the way the circuit looks , the schematic aims to capture, on a more general level, the way it works . This may be contrasted with

1066-399: The initial cost of CBM can be high. It requires improved instrumentation of the equipment. Often the cost of sufficient instruments can be quite large, especially on equipment that is already installed. Wireless systems have reduced the initial cost. Therefore, it is important for the installer to decide the importance of the investment before adding CBM to all equipment. A result of this cost

1107-472: The interconnections between circuit components in the schematic diagram does not necessarily correspond to the physical arrangements in the finished device. Unlike a block diagram or layout diagram , a circuit diagram shows the actual electrical connections . A drawing meant to depict the physical arrangement of the wires and the components they connect is called artwork or layout , physical design , or wiring diagram . Circuit diagrams are used for

1148-440: The maintenance personnel of today is more than ever able to decide what is the right time to perform maintenance on some piece of equipment. Ideally, condition-based maintenance will allow the maintenance personnel to do only the right things, minimizing spare parts cost, system downtime and time spent on maintenance. Despite its usefulness of equipment, there are several challenges to the use of CBM. First and most important of all,

1189-690: The most important differentiators in a future where environmental issues become more important by the day. Another scenario where value can be created is by monitoring the health of a car motor. Rather than changing parts at predefined intervals, the car itself can tell you when something needs to be changed based on cheap and simple instrumentation. It is Department of Defense policy that condition-based maintenance (CBM) be "implemented to improve maintenance agility and responsiveness, increase operational availability, and reduce life cycle total ownership costs". CBM has some advantages over planned maintenance: Its disadvantages are: Today, due to its costs, CBM

1230-564: The one-line diagram, three different per-phase schematic diagrams are obtained, known as sequence diagrams : positive sequence diagram , negative sequence diagram , and zero sequence diagram . Each of these diagrams can be represented as an impedance diagram or as an admittance diagram. Schematic diagrams are used extensively in repair manuals to help users understand the interconnections of parts, and to provide graphical instruction to assist in dismantling and rebuilding mechanical assemblies. Many automotive and motorcycle repair manuals devote

1271-1033: The original constituent materials where possible, or with suitable polymer technologies when not. Preventive maintenance ( PM ) is "a routine for periodically inspecting" with the goal of "noticing small problems and fixing them before major ones develop." Ideally, "nothing breaks down." The main goal behind PM is for the equipment to make it from one planned service to the next planned service without any failures caused by fatigue, extreme fluctuation in temperature(such as heat waves ) during seasonal changes, neglect, or normal wear (preventable items), which Planned Maintenance and Condition Based Maintenance help to achieve by replacing worn components before they actually fail. Maintenance activities include partial or complete overhauls at specified periods, oil changes, lubrication, minor adjustments, and so on. In addition, workers can record equipment deterioration so they know to replace or repair worn parts before they cause system failure. The New York Times gave an example of "machinery that

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1312-485: The other wire (similar to how jumper wires are used). A common, hybrid style of drawing combines the T-junction crossovers with "dot" connections and the wire "jump" semi-circle symbols for insulated crossings. In this manner, a "dot" that is too small to see or that has accidentally disappeared can still be clearly differentiated from a "jump". On a circuit diagram, the symbols for components are labelled with

1353-484: The parameters are represented as impedances and voltage sources, the equivalent per-phase schematic diagram is called an impedance diagram . If all of the parameters are represented as admittances and current sources, the equivalent per-phase schematic diagram is called an admittance diagram . If the power system is unbalanced, but it is linear (or can be approximated by a linear system), then Fortescue's theorem ( symmetrical components ) can be applied. In this way, from

1394-467: The physical construction of the device. For example, the symbol for a resistor dates back to the time when that component was made from a long piece of wire wrapped in such a manner as to not produce inductance, which would have made it a coil . These wirewound resistors are now used only in high-power applications, smaller resistors being cast from carbon composition (a mixture of carbon and filler ) or fabricated as an insulating tube or chip coated with

1435-856: The rudiments of circuit diagrams and their functioning. Use of diagrammatic representations of circuit diagrams can aid understanding of principles of electricity. Principles of the physics of circuit diagrams are often taught with the use of analogies, such as comparing functioning of circuits to other closed systems such as water heating systems with pumps being the equivalent to batteries. Repairing The technical meaning of maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery , building infrastructure and supporting utilities in industrial, business, and residential installations. Over time, this has come to include multiple wordings that describe various cost-effective practices to keep equipment operational; these activities occur either before or after

1476-984: The supply of spare parts, accessories, raw materials, adhesives, sealants, coatings and consumables for aircraft maintenance at the utilization stage. In international civil aviation maintenance means: This definition covers all activities for which aviation regulations require issuance of a maintenance release document (aircraft certificate of return to service – CRS). The marine and air transportation, offshore structures, industrial plant and facility management industries depend on maintenance, repair and overhaul (MRO) including scheduled or preventive paint maintenance programmes to maintain and restore coatings applied to steel in environments subject to attack from erosion, corrosion and environmental pollution. The basic types of maintenance falling under MRO include: Architectural conservation employs MRO to preserve, rehabilitate, restore, or reconstruct historical structures with stone, brick, glass, metal, and wood which match

1517-468: The system health and predict a breakdown before it happens. This strategy allows maintenance to be performed more efficiently, since more up-to-date data is obtained about how close the product is to failure. Predictive replacement is the replacement of an item that is still functioning properly. Usually it is a tax-benefit based replacement policy whereby expensive equipment or batches of individually inexpensive supply items are removed and donated on

1558-403: The top of the page, with grounds, negative supplies, or other return paths towards the bottom. Schematic drawings intended for maintenance may have the principal signal paths highlighted to assist in understanding the signal flow through the circuit. More complex devices have multi-page schematics and must rely on cross-reference symbols to show the flow of signals between the different sheets of

1599-462: The use of electronics design automation (EDA) tools. The EDA tools arrange and rearrange the placement of components and find paths for tracks to connect various nodes. This results in the final layout artwork for the integrated circuit or printed circuit board . A generalized design flow may be as follows: Teaching about the functioning of electrical circuits is often on primary and secondary school curricula. Students are expected to understand

1640-427: The whole design flow and linked to other EDA tools for verification and simulation of the circuit under design. Programmable logic controllers (PLC) can be programmed using ladder diagrams . In electric power systems design, a schematic drawing called a one-line diagram is frequently used to represent substations , distribution systems or even whole electrical power grids. These diagrams simplify and compress

1681-480: Was introduced to try to maintain the correct equipment at the right time. CBM is based on using real-time data to prioritize and optimize maintenance resources. Observing the state of the system is known as condition monitoring . Such a system will determine the equipment's health, and act only when maintenance is actually necessary. Developments in recent years have allowed extensive instrumentation of equipment, and together with better tools for analyzing condition data,

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