Howard W Penrose, Ph.D.
VP Electrical Reliability Programs
T-Solutions, Inc.
hpenrose@tsoln-inc.com
The Concept of RCM-Based Motor Management Part 2
The flavor of RCM Program that is used for an RCM-Based approach to Motor Diagnostics is the Classical RCM concept put forward by the fathers of RCM, Nowlan and Heap. This program has been adopted by the US Navy as the MIL-P-24534A, which has been in place since 1985. This standard outlines a process for the implementation of RCM. The basic steps of the standard are:
1. Set boundaries for the system being reviewed
2. Generate a functional block diagram and partitioning of the system under review
3. Determine functional failure analysis
4. Determine functionally significant items of the system
5. Perform a failure modes and effects analysis
6. Go through a logic tree in order to determine the effectiveness of maintenance tasks for the FMEA
7. Determine servicing and lubrication analysis
8. Set maintenance requirements
9. Draft and evaluate maintenance procedures
10. Define the maintenance tasks
11. Determine tasks for inactive equipment
12. Develop corrective maintenance processes and specifications
13. Develop and prepare procedures and specifications
14. Utilize continuous improvement of the RCM process, such as the Backfit process.
Step 1: Set Boundaries for the System Being Reviewed
Set a system for setting boundaries within the facility being reviewed. This is important, as the RCM process moves forward, to ensure that there is no duplication of effort.
Step 2: Generate a Functional Block Diagram
The purpose of the block diagram is to provide guidance through all of the following steps. It involves noting all of the inputs and outputs of the components and any protective devices in the system.
Step 3: Determine the Functional Failure Analysis
First write out a complete description of the function of the system as it is intended to be used. For instance: The pump system is designed so that 480V, 60 Hz, 100 Amps is made available to an electric motor which operates at 1780 RPM. The power is transferred via direct shaft coupling to a pump which provides at least 200 gpm to a height of 100 ft.
The next step is to identify the internal and external interfaces. Then identify the functional failures of the system.
A Functional Failure exists when a system or subsystem ceases to provide a required function; Whether the function is active, passive, evident, or hidden. MIL-P-24534A