Yosemite Watthour Meter
Three Wire, 120 Volts to Neutral, 240 Volts Line to Line
The Yosemite watthour meter is used to measure the power used in most homes in North America, 240 volts between the two hot wires and 120 volts between either hot hire and neutral. It consists of an electronics module, two current transformers (CTs) and an electro-mechanical counter that displays the accumulated power used.
Available
Configurations
The Yosemite meters are available in a variety of configurations. Check the options
in the Part Numbering Guide at the bottom of this page for details.
Current
Capabilities
Meters are rated by the maximum current that can flow through the
current transformers. Generally speaking, the meter should be
rated at or above the rating of the breaker that will protect the
circuit to be measured. Meters using solid-core CTs are
available in 20, 100 and 200 amp versions. Meters using
split-core CTs are available in 200, 500, 750, 1000 and 1500 amp
versions.
Resolution
Meters of 200 amps or less usually have a resolution of 0.1
kwh. Meters over 200 amps usually have a resolution of 1.0 kwh. A test
mode forces a resolution of 0.01 kwh. Meters can be ordered with any of these
reolutions or a special low current resolution of 0.01 kwh normal, 0.001 kwh (1
watthour) test. The California approved meter has no test position and always runs
in 0.01 kwh resolution.
Automatic
Meter Reading (AMR)
In addition to stand-alone meters that must be manually read, the
meter is available with the following AMR options.
KYZ Pulse - An optically isolated output
toggles between open and closed every time the counter advances.
These meters are frequently used with radio data collection systems in
apartment buildings.
50ms Pulse - An optically isolated output that
closes for 50ms then opens every time the counter advances.
Dedicated Twisted Pair - A local meter network
that communicates over a twisted pair of wires. Any number of
meters can be connected to an RS-232 interface. The RS-232
interface can be connected directly to a Windows compatible computer,
to a telephone modem, or to a TCP/IP interface module. You can
use the free Microsoft Access application to read the meters or write
your own custom application. See the
documentation section for more info.
Power
Line Carrier - This system is the same as the Dedicated
Twisted Pair except that communication is via the power line instead of
separate wires. Because of interference from nearby ground fault
interrupters and switching power supplies, this system works best in
marinas.
Enclosures
The Yosemite meter is available in a variety of enclosures, either for
a single meter or multiple meters. See the enclosures page for
more info.
OEM Versions
The Yosemite meter is also available in an OEM version so that it can
be installed in a third party NEMA enclosure. This is usefull
when the meters are to be installed in power pedestals in a marina or
RV park. A stainless steel mounting plate is available for
mounting the display counters in the enclosure.
Alternate Configurations
The Yosemite can also be used with just one CT if desired.
If the meter is not to be mounted
in a permanent location, buying a three element meter now gives you the flexibility to use
it anywhere in the future.
Accuracy and Safety Certifications
Davidge Controls certifies that all our watthour meters meet or exceed
the accuracy standards of ANSI C12.1(2001), the national standard for
watthour meters that applies to all the utility companies in the
country.
The California Division of
Measurement Standards has tested the 100 and 200 amp versions of the Yosemite meter and
approved them for use in revenue metering within the state. Each meter must be
tested and sealed by the local Weights & Measures office. Be sure to read about the
California regulations.
All models of the Yosemite meter
carry an Underwriters Laboratories Recognized Component mark.
All models of the Yosemite meter
carry an Underwriters Laboratories Recognized Component mark.
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