Electrical O&M Data Requirements

Engineered Systems, March, 2001 by Timothy Coyle

Don't leave the O&M staff "in the dark."

Most equipment specifications include a requirement that the vendor or contractor provide complete operations and maintenance (O&M) data for the equipment to the owner following shipment and prior to project closeout. General requirements for O&M manuals are probably familiar to you and already addressed in your specifications. Keep the following specific requirements in mind when reviewing O&M data for the electrical systems and components of hvacr equipment.

MOTOR DATA

Accurate data on the motor(s) that operate the equipment is critical. A minimum standard should be indusion of a data sheet for each motor listing all of the basic parameters that appear on the motor nameplate such as manufacturer, type, frame, horsepower, bearing part numbers, etc. Nameplates on installed motors often become worn, damaged, dirty, or inaccessible and the presence of this information in the manual is invaluable.

Larger motors and motors in special applications such as high-inertia load or plugging duty have additional performance parameters that should be included in the data sheet. These may include efficiency and power factor, minimum time between starts, maximum stall time, acceleration time of the motor and load, minimum terminal voltage during starting, and many others.

Much of this information was used by the electrical engineer during design to select fuse or circuit breaker ratings, determine starting method, and size the electrical system, and may be needed to troubleshoot problems within the motor controller or the facility electrical system.

SCHEMATIC AND WIRING DIAGRAMS

Following motor data, the most important electrical item is complete and accurate schematic and wiring diagrams. Schematics show the electrical logic of the power and control circuits and are used to identify the cause of failure. Wiring diagrams show the physical connections of the wiring between components and terminal boards. For simple systems, these may be combined into a single diagram in which wire and terminal numbers are shown on the schematic diagram.

Electrical diagrams should be specific for the model of equipment and the options or accessories furnished. Universal diagrams that include information for multiple models and for all possible options increase the amount of time required for troubleshooting. All wire, terminal, and component labels on the drawing must correspond to labels provided on the equipment. A legend or bill-of-material should be provided when acronyms or abbreviations are used. Field wiring should be discriminated from factory wiring, typically by dashes and solid lines, and all field wiring connections should be clearly identified.

Ensure that schematic and wiring diagrams are completely legible. The format of most O&M manual submittals is bound 8 1/2- by 11-in. pages. Reduction of large drawings to this size or even folded 11- by 17-in. size often results in text and details that are too small to read; the original drawing size is preferred.

COMPONENT DATA

Provide catalog data and the original manufacturer's instructions for all out-sourced electrical items like starters, switches, relays and control transformers. These will be needed if an individual component requires repair or replacement. This information should be cross-referenced to the electrical bill-of-material or the component labels used on the electrical diagrams.

THE FIELD SERVICE REPORT

The final piece of the electrical O&M puzzle is the manufacturer's field service or startup report. This should include not only the usual checklist verifying correct installation and operation, but also list the startup values of equipment operating parameters such as voltage, current, temperature, etc., and the "as-left" settings of protective devices like overload relays or temperature switches. The results of acceptance tests, such as motor winding insulation resistance (Megger(r)) or bearing vibration, that establish baseline values for future predictive maintenance testing should be recorded.

WORTH THE EFFORT

The effort required to obtain complete O&M data for equipment is slight in comparison to the cost in time, and often production, of attempting to troubleshoot or repair a problem without it. You may spend time and effort educating the contractor or vendor's representative as to the specifics of the required data and the reason it is being requested. Common objections include claims that the information is proprietary, the owner is not qualified to maintain the equipment, a service agreement is in place, or occasionally: "We cannot obtain it from our suppliers." However, persistence is usually rewarded, particularly if complete O&M manuals are considered a punchlist item requiring resolution prior to final payment.

Coyle is an associate and electrical group leader with Sebesta Blomberg (Minneapolis), where he oversees utility design and electrical commissioning.