The lead-acid battery is a commonly used chemistry. The flooded version is found in automobiles and large UPS battery banks. Most smaller, portable systems use the sealed version, also referred to as gel-cell or SLA. The lead-acid chemistry is commonly used when high power is required, weight is not critical, and cost must be kept […]
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Out of sight, out of mind does not or, at least, should not apply to a facility ground system. Grounding is a crucial element in achieving reliable operation of electronic equipment. If a ground system has been buried for 10 years or more, it is due for an inspection. Soil conditions vary widely, but few areas
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All too often, ac power switchgear is installed at a facility and forgotten until a problem occurs. A careless approach to regular inspection and cleaning of switchgear has resulted in numerous failures, including destructive fires. The most serious fault in any switchgear assembly is arcing involving the main power bus. Protective devices may fail to
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Maintenance of the facility electrical system is a key part of any serious energy-management effort. Perform the following steps on a regular basis: • Measure the current drawn on distribution cables. Document the measurements so that a history of power demand can be compiled. • Check terminal and splice connections to make sure they are
Conserving energy is a big part of the power bill reduction equation, but it is not the whole story. The peak demand of the customer load is an important criterion in the utility company’s calculation of rate structures. The peak demand figure is a measure of the maximum load placed on the utility company system
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The kilowatt-hour (kWh) usage of a facility can be reduced by turning off loads such as heating and air conditioning systems, lights, and office equipment when they are not needed. The installation of timers, photocells, or sophisticated computer-controlled energy-management systems can make substantial reductions in facility kWh demand each month. Common sense will dictate the
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Be familiar with first aid treatment for electric shock and burns. Always keep a first aid kit on hand at the facility. Figure illustrates the basic treatment for electric shock victims. Copy the information, and post it in a prominent location. Better yet, obtain more detailed information from your local heart association or Red Cross
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Advantages of liquid fuels over the solid fuels The following are the advantages of liquid fuels over the solid fuels: (i) The handling of liquid fuels is easier and they require less storage space. (ii) The combustion of liquid fuels is uniform. (iii) The solid fuels have higher percentage of moisture and consequently they burn
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THERMAL CONSIDERATIONS The losses in the windings and the core cause temperature rises in the materials. This is another important area in which the temperatures must be limited to the long-term capability of the insulating materials. Refined paper is still used as the primary solid insulation in power transformers. Highly refined mineral oil is still
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The term load losses represents the losses in the transformer that result from the flow of load current in the win dings. Load losses are composed of the following elements. Resistance losses as the current flows through the resistance of the conductors and leads. Eddy losses caused by the leakage field. These are a function
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