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 ELECTRIC METERING
CHAPTER 9.
Section 1. REQUIREMENTS AND USE
1. INTRODUCTION. Metering electrical energy involves use of many types of
meters and associated devices. In many cases, totalizing of kilowatthour
(kWh) usage during a time interval is adequate for studies and billing
purposes. Many more parameters of electric power can be measured to provide
insight into electrical demand requirements. Some parameters measured to
complete a more accurate and informative analysis of an electrical system are
as follows:
Mid-peak kW demand
q Voltage
q
q Offpeak kW demand
q Ampere
q Phase angle
q Time-of-use
q Power factor
Kilowatt
q
q Real power
Kilowatthour
q
q Apparent power
q Onpeak kW demand
2. IMPORTANCE OF METERING. Metering electrical energy serves three important
purposes: provides energy audit data, identifies distribution of costs to
users, and sets standards to be used to evaluate performance. Meter
installation can be costly, but the return in savings usually is worth the
investment. Based on data from 1980, the cost of installing a kilowatthour
meter ranges between $300 and $1,000.
2.1 Audits. To obtain useful information for an audit, a survey requires a
metering system and a formally standardized method of collecting and reducing
data. Percentages of energy efficiency and pinpointing inefficient equipment
are results that an audit will produce. An energy profile will do the
following:
q Aid
in establishing and refining energy use by department or area.
Establish and improve accountability.
q
Measure cost reductions.
q
q Determine
equipment capabilities and load factors.
q Help
in planning facility modifications and expansions.
Provide data to analyze variance from standards.
q
Identify successful energy management projects.
q
2.2 Accurate Charges. Accurate distribution of charges to energy users is
needed. Contrary to limited metering of the past, sufficient and discriminate
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