Repair time

Serviceability. ServiceabiUty is defined as the degree of ease (or difficulty) with which a system can be repaired. This measure specifically considers fault detection, isolation, and repair. RepairabiUty considers only the actual repair time, and is defined as the probabiUty that a failed system is restored to operation in a specified interval of active repair time. Access covers, plug-in modules, or other features to allow easy removal and replacement of failed components improve the repairabihty and serviceabihty (see also Electrical connectors). 

N1 886 is a similar pump study. Repair time data are collected as a part of the IPRDS. 

EPRI NP-2433 addresses diesel generator reliability at nuclear power plants. The sources include plant records, utility records, and LERs. The report gives frequency of failure to start, failure. o continue running, and mean repair times. 

Repair-time dislribution parameters Repair times Mdimcnancri rcpoi f-. control phi -, fiv. ... 

Since dependency analysis is not needed, we can go on to the BUILD program. Go to FTAPSUIT and select 5 "Run Build." It asks you for the input file name including extender. Type "pv.pch," It asks you for name and extender of the input file for IMPORTANCE. Type, for examle, "pv.ii . It next asks for the input option. Type "5" for ba.sic event failure probabilities. This means that any failure rates must be multiplied by their mission times as shown in Table 7.4-1. (FTAPlus was written only for option 5 which uses probabilities and error factors. Other options will require hand editing of the pvn.ii file. The switch 1 is for failure rate and repair time, switch 2 is failure rate, 0 repair time, switch 3 is proportional hazard rate and 0 repair time, and switch 4 is mean time to failure and repair time.)... 

Over 100 data sheets, conta/ning failure rate estimates for various failure modes and some repair times. 

Fallnre canae Failure Fallnre popnlation ( ) Repair time s ... 

The failure rates and times-to-restore developed used a variety of data sources and data construction methodologies and are presented in Section 2. The principal methodology used is a kind of failure mode analysis for each component several principle modes of failure are analyed by characteristics including frequency of occurence, repair time, start-up time, and shut-down time. From these an average failure rate is developed and expressed as failures per million hours and mean time between failure(MTBF). 

RAC publications include data summaries for specific component types, such as hybrid microcircuits, small, medium and large-scale integration digital devices, linear and interface devices, digital monolithic devices, and discrete semiconductors. In addition, there are reliability and equipment maintenance data books that provide the failure and repair time data on military electronic equipment by application such as subsystem. 

Predictive maintenance was shown to reduce the actual time required to repair or rebuild plant equipment. The average improvement in mean-time-to-repair, MTTR, was a reduction of 60 per cent. To determine the average improvement, actual repair times before the predictive maintenance program were compared to the actual time... 

Equations 11-19 through 11-25 assume a negligible repair time. This is usually a valid assumption because on-line process equipment is generally repaired within hours, whereas the inspection intervals are usually monthly. 

Compute the availability and the unavailability for both the alarm and the shutdown systems of Example 11 -2. Assume that a maintenance inspection occurs once every month and that the repair time... 

Depositions are inexpensively performed at ambient conditions without the need for expensive, specialized equipment such as reaction furnaces and/or vacuum chambers, reducing repair times and costs. 

The economic loss term includes two types of losses i) economic loss associated with failed equipments that have not been repaired (for example, a fouled heat exchanger can continue operating but at reduced heat transfer rate, ii) economic loss due to imavailability of equipment during repair time. The economic loss is calculated as a loss rate ( per day) multiplied by the duration of the period within which the loss is realized. To determine economic loss rates, an analysis is carried out on each piece of equipment to determine the economical effects of equipment failure, which include reduced production rate or even shutdown, the deterioration of product quality, etc. 

An equipment may have different failure modes involving different parts of the equipment. It can fail because of deterioration of mechanic parts (possible consequence is complete failure that requires equipment replacement) or electronic parts malfunction (partial failure that can be repaired). Different failure modes need different repair costs and repair times and induce different economic losses. The sampling of different failure modes of equipment is done as follows i) assign a probability of occurrence for each type of failure mode using information on how common a failure mode is, ii) at the simulated failure time of the equipment, the type of failure mode that actually occurred is sampled in accordance with the failure modes probability of occurrence. 

The cost of corrective maintenance, the repair time and the economic losses are determined corresponding to the type of failure modes identified. 

After required drug exposure/repair time, pellet cells by centrifuging at 200g for 5 min at 4°C. Remove supernatant and resuspend cells to a final concentration of 2.5 x 104 cells/mL in the appropriate tissue culture media maintained at 4°C ensuring that a single-cell suspension has been achieved (see Note 11). 

Suppose the station can fail even when they are idling. Let the mean time to failure, and repair times of stage i, be and D, respectively, for i = 1, 2,. . . , m. With no inventory bank, all stations in the line stop as soon as any station fails. Then it follows that... 

Consider a transfer line with m stages and m - 1 banks of capacities Zi, Z2, , Zm-i- The number of cycles of operation before failure and the repair times aU have geometric distributions with mean 1/flj and 1/bi respectively for stage i, I = 1,. . . , m. The parameters of stage i are then (a, b ). 

Maintainability is defined as the probability that a failed system can be made operable in a specified interval of downtime. As shown in Figure 2, the downtime includes the failure detection time, the active repair time, the logistics time connected with the repairs of the product, and all the administrative time. The maintainability function describes probabilistically how long a system remains in the failed state. 

Repairability deals only with the active repair time and can be defined by the time to actively repair random variable and the associated distribution. Repairability is defined as the probability that a failed system be restored to a satisfactory operating condition in a specified interval of active repair time. This measure is more valuable to the administration of the repair facility since it helps to quantify the workload for the facility and its workers. 

Intrinsic availability is more restrictive than availability because it is limited to operating and active repair time only. 

Maintainability is the probability that a system in need of maintenance will be retained in or restored to a specified operational condition within a given period. Thus, the underlying random variable is the maintenance time. Let T be the repair time random variable. Then the maintainability function Mif) is given by... 

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