REG NASA-LLIS-0870-2000 Lessons Learned Fault Isolation Using Terminal Blocks.pdf

1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-20a71 Center Point of Contact: KSCa71 Submitted by: Wilson HarkinsSubject: Fault Isolation Using Terminal Blocks Practice: Utilize terminal blocks (strips) in control cabinets and junction boxes to provide common test poin

2、ts for fault isolation.Programs that Certify Usage: This practice has been used on the following KSC systems: Space Transportation System (STS), Facilities and Ground Support Equipment, Examples: Vehicle Assembly Building (VAB) 325 Ton Bridge Cranes, Orbiter Processing Facility Three (OPF-3) 30 Ton

3、Bridge Cranes.Center to Contact for Information: KSCImplementation Method: This Lesson Learned is based on Maintainability Technique number OPS-12 from NASA Technical Memorandum 4628, Recommended Techniques for Effective Maintainability.This practice reduces the amount of time spent during troublesh

4、ooting and maintenance of ground support and facility equipment by:a71 Centralizing test point locations for electrical circuits.a71 Clearly labeling wire/terminals for ease of locating a particular circuit.a71 Making spare wires available for wire replacement or system modifications.Provided by IHS

5、Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Fault Isolation is simplified by utilizing terminal blocks in the circuitry of ground support and facility equipment. The terminal blocks are used to modularize the equipments circuits at locations that are convenient

6、 to personnel access. Examples of convenient locations are control panels and junction boxes.Each wire at the terminal blocks is labeled clearly. The label is the wire number listed on the electrical schematic. Clear, meaningful labels and a centralized location will reduce the time required for mai

7、ntenance personnel to locate and identify circuits necessary to troubleshoot. The centralized location makes component isolation easier. Only a screwdriver is usually required to disconnect wires during troubleshooting.Consideration must be given to the design of the terminal block. The screw termin

8、als should be recessed into the block or separated by non-conductive dividers so that tools and probes cannot create a short across adjacent terminals during troubleshooting or accidental contact. Consideration must also be given to wiring layout. Signal wiring should be separated from power and con

9、trol wiring to reduce the chance of electrical interference. Any high voltage wiring should be separated and a cover placed over the terminal block to reduce the danger to personnel. If required, covers should be placed over all terminal blocks if there is a concern regarding debris and foreign obje

10、cts causing electrical short circuits.Other benefits are realized from this practice. Control panels and junction boxes are located in areas that are safe for personnel access, reducing the need to expose personnel to dangerous conditions. Spare wires between control cabinets and junction boxes are

11、included in the original design. The spare wires can be used to replace existing wires if they are damaged or to add new components during system modifications. A systematic approach to wiring is necessary to implement this practice which reduces wiring errors at startup.Impact of Non-Practice: Main

12、tenance effort and system downtime will be reduced by the implementation of this practice.Related Practices: N/AAdditional Info: Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Approval Info: a71 Approval Date: 2000-04-20a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-