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 2.4.7 Availability and Compatibility. PSRs of various capabilities are
available in the commercial q arketplace. Prices and accessories vary
considerably. When renting, leasing, or purchasing equipment, ensure that all
components needed to undertake a complete survey are obtained. Additionally,
ensure that survey equipment components are compatible with each other.
2.5 Tape Recorder Meters. A tape recorder meter is used often for periodic
monitoring because it provides a graph that is easy to analyze. Tapes offer
immediate data for use in comparing actual power demand with rate schedule
provisions of the utility. These meters are portable and do not interrupt
service when connected. The meter uses clamp-on type current transformers and
may use battery power or 100 volts alternating current (VAC).
2.6 Time-of-Use Meter. Time-of-use meters have not changed for many years;
improvements to them have been evolutionary rather than revolutionary. With
availability of integrated circuit processors and electronic digital memories,
tasks performed by these meters that were originally difficult or impossible,
are now easier. This meter is based on a standard watthour meter structure
with pulse output to an integral microprocessor-based register. With a
precise internal clock it can be programmed to handle any time-dependent
provisions in a rate schedule, such as time-of-day and time-of-year rate
changes. The reduction of meter data can provide the following types of
information:
Total kWh
Onpeak kWh
q
q
q Offpeak kWh
q Mid-peak kWh
q Mid-peak kW demand
q Onpeak kW demand
q Offpeak kW demand
2.7 Power Factor and Negative Sequence Meters. Power factor and negative
sequence meters are available to meet specific needs.
2.7.1 Power-Factor-Meter. A power-factor meter indicates either a single or
three-phase value leading or lagging. It requires both potential and current
connections much the same as a wattmeter. Most power-factor meters are
single-phase devices and are not accurate on either imbalance voltage or
current on a three-phase system. Some electronic meters respond to zero
crossings and, in the presence of distortion, are not accurate.
2.7.2 Negative Sequence Meter. A negative sequence meter indicates the
presence and magnitude of negative sequence voltage or current, usually
associated with system imbalance, fault conditions, or both.
OTHER ELECTRICAL METERING COMPONENTS
3.
3.1 Pulse Device (Digital). A widely used method of demand metering is the
block interval, so called because a kWh measurement is totalized over a block
of time, typically a 15- or 30-minute period. The most flexible and easily
computerized block interval metering technique is pulse totalization. Each
pulse represents a specified amount of kilowatt hours read by the meter from
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