MTBF, MTTR & MTBM, Reliability metrics
1- MTBF (Mean time between failures), a measure of asset reliability, is the average operating time between failures for an asset or component. It is used primarily for repairable assets and elements of similar type. MTBF is used to assess the reliability of a repairable asset or component.
Reliability is usually expressed as the probability that an asset or component will perform its intended function without failure for a specified period under specified conditions.
MTBF mathematical formula is operation time in hours divided by the number of failures, so a higher MTBF indicates better asset reliability.
2- MTTR (Mean Time to Repair or Replace) is a primary measure of the maintainability of a repairable asset. It represents the average time required to repair a failed component or asset, regardless of whether it is repaired or replaced.
MTTR assesses maintainability, including the effectiveness of plans and procedures.
MTTR mathematical formula is Total repair or replacement time (hours) divided by the number of repair/replacement events.
Prediction of the number of hours a system or component will be unavailable while undergoing maintenance is vital in reliability and availability studies. Meanwhile, repair yields much information to help reliability engineers make informed decisions such as repair or replacement, hiring, optimizing maintenance schedules, storing parts onsite, or switching parts strategy. For example, as the system ages, it may take longer to repair systems. MTTR will trend upwards, prompting the repair versus replacement decision.
3- MTBM (Mean Time Between Maintenance) is the average length of operating time between one maintenance action and another maintenance action for an asset or component. This metric is applied only for maintenance activities that require or result in function interruption.
MTBM is a measure of reliability considering the maintenance policy, which is the total number of life units expended by a given time divided by the total number of maintenance events (scheduled and unscheduled) performed on that item.
Reliability methods such as MTBF, MTTR, and MTBM apply to products or specific components. However, MTBF remains an essential measure of a system’s reliability for most products. A recent Emerson study on Data Center maintenance investigated the increase in Mean Time Between Failure (MTBF) on assets based on the inspection frequency and preventative maintenance visits. Going from one to four annual inspections would increase MTBF by more than 5x. In this manner, Condition-based Maintenance and increasing inspection frequency can positively impact a company’s bottom line. However, companies will only implement increased inspection frequency if it is convenient and safe for their personnel. Assessing the condition of critical electrical assets by observing the state of the energized system under normal load is imperative for continuous, reliable operation. It allows maintenance engineers to prioritize and optimize resources by helping them identify what maintenance is required and determine the urgency level of the equipment fault, thus minimizing parts cost, system downtime, and time spent on often unnecessary fixed schedule maintenance.
Infrared windows, Ultrasound sensors & ports, wireless temperature monitoring systems & critical assets management systems are all Electrical Maintenance Safety Devices & Solutions (EMSD) made by IRISS, Inc. It is designed and built to ensure the operator's safety while collecting sufficient data about the health condition of the asset and reducing unexpected failures.
