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H8025 TYPICAL METASYS SETUP
1. Define a hardware object
Type "N2 Device", Device type: "VND"
2. Add kWH Accumulator (Consumption) Point
Directly map BI point 1 to an accumulator (ACM) object at Metasys.
Refer to the Range/Value column in the point map (page 4) for the
"pulse constant" which corresponds to the CT size used. The correct pulse
constant must be used to obtain accurate data. The "Rate Constant"
should be "Hour".
3. Add kW (Instantaneous Demand) Point Directly map AI point 2 to an Analog
Object. Do not use alarm or warning limits (see below). Alternatively, the
CS model file H8025.DDL may be used.
4. Add kWH AI Point (optional)
Directly map AI point 1 to an analog object. Do not use alarm warning
limits. Alternatively, the CS model file H8025.DDL may be used. This AI
point provides direct kWH accumulation display.
SPECIAL METASYS SETUP OPTIONS
Setting Alarm or Warning Limits
The H8025 and H8026 do not support alarm and warning status reporting
for AI points. If alarm and/or warning limits are required, first define a CS
object. Then map an AD object to each CS object AI point value attribute.
However, alarm and warning limits may be used with the accumulator point.
Resetting the kWH Accumulator
Point BO-1 provides a "reset button" that will cause the kWH accumula-
tor to reset when commanded to "1". This point will automatically return to
"0" immediately after the kWH accumulator is reset. BO-1 should be directly
mapped to a BO object defined with the auto restore flag set to "N". This
will prevent an accidental kWH reset if themeter goes off-line and returns.
BO-1 should not be defined with a CS Model, because the CS Model would
automatically set the auto restore flag to "Y".
Using Multipliers to Scale Data Points
High voltage installations where the meter is powered by a potential
transformer will require the data to be multiplied by the ratio of the
transformer used. Most of these applications use pre-installed 5 amp output
current transformers, with the 5 amp line wrapped many times through the
H8025/H8026 meter. Two multipliers exist, one for the voltage, and one for
the effective current ratio. For example, a 300:5 amp CT is pre-installed and
the 5 amp loop is wound 20 times onto the H8026 meter; effective current
ratio would be 3. If a 20:1 potential transformer is used, then voltage points
would need to be multiplied by 20, current points would need to be multiplied
by 3, and power points would need to be multiplied by 60. Power factor points
do not use multipliers.
The kWH accumulator may be multiplied by changing the "pulse
constant".
To apply multipliers to AI points, use a GPL process to do the math and
write the multiplied value to a pseudo-point.
H8026 TYPICAL METASYS SETUP
Define a hardware object
1.
Type "N2 Device", Device type: "VND"
Add kWH Accumulator (Consumption) Point
2.
Directly map BI point 1 to an accumulator (ACM) object at Metasys.
Refer to the Range/Value column in the point map (page 5) for the
"pulse constant" which corresponds to the CT size used.
The correct pulse constant must be used to obtain accurate data.
The "Rate Constant" should be "Hour".
3.
Compile the CS model file (H8026.DDL) to add the CS models for
the H8026 to your Metasys database. Type "DDL H8026".
Add CS Object using the model "H8026A"
4.
This allows access to the first 16 AI points.
Add CS Object using the model "H8026B"
5.
This allows access to the remaining AI points.
Displaying kWH
Use totalization to display kWH values. When displayed normally, the
accumulator will show kW instead of kWH. The kW value associated with the
accumulator should agree with AI-2, but it will respond slowly as Metasys®
counts kWH over a period of time to compute kW. Alternatively, AI-1 provides a
direct view of the accumulated kWH. For large values, BI-1 will provide better
precision than AI-1.
Presetting the kWH Accumulator
In some cases it may be necessary to preset the kWH accumulator to
a specific value. This can be accomplished by writing to ADI-1 and ADI-2.
Computing the values to write to these points is not simple. Divide the desired
kWH value by the kWH/count constant that corresponds to the CT size of the
meter (see the point map), and round off to the nearest whole number. This is
the "raw count". Divide the raw count by 65536 and round down to the nearest
whole number. If the value was greater than 32767, subtract 65536. This is the
value to write to ADI-2. Take the raw count, divide by 65536, subtract out the
integer portion, leaving only the part to the right of the decimal point, and then
multiply by 65536. If the value was greater than 32767, subtract 65536. This
is the value to write to ADI-1. Both points should be written when there is no
power (AI-1 reads zero) to prevent the values from changing unexpectedly
as they are written.
Using the Avg/Min/Max Points (H8026)
The Average Real Power (AI-5), Minimum Real Power (AI-6), and Maximum
Real Power (AI-7) points measure their respective data during a period of time.
They begin after BO-2 is commanded to "1". A typical usage would be to read
these points at a regular interval, such as every 15 minutes, and then command
BO-2 immediately after reading them. BO-2 should be directly mapped to a BO
object defined with the auto restore flag set to "N".
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