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8-10
IB02601006E
www.eaton.com
Chapter 8:
Programming the IQ 250/260 IQ 250/260 Meter
Configuring Energy, Power Scaling, and Averaging
Use this setting to configure:
• The display of Power in the meter
• The display and storage of Energy in the meter
• The interval over which Average values are computed.
Functional Overview of Energy Settings and Averaging
:
Energy Scaling
Energy Setting
includes:
•
Digits
(the number of digits in the reading)
•
Decimals
(the number of decimal places in the reading)
•
Energy Scale
: the scale of the reading – unit; kilo (number times 1000); Mega (number times 1 million).
Energy settings allow you to balance the resolution (or accuracy) of the energy stored, with the interval over which
energy rollover occurs.
For example
, the maximum resolution for a k scale reading is: 99999.999k.
To calculate the speed at which the energy will rollover, you must know the
Energy Full Scale
, which is computed
from the CT and PT Full Scale values (see Section 9.2.4.1). The
formula
for calculating
Energy Full Scale
is:
Wye system
: CT Full Scale x PT Full Scale x 3
Delta system
: CT Full Scale x PT Full Scale x 3 x √3
For example
, for a CT Full Scale of 2000, PT Full Scale of 14400, Wye system:
2000 x 14400 x 3=86400000
In this example, the energy will increment at 86400000 Watts per hour, or 24000 Watts per second.
This value allows you to determine the number of digits, decimal places, and energy scale you want to configure for
the Energy settings, when you take into account the rollover time. To determine the number of hours before rollover,
use this
formula
:
[Max Resolution]/[Full Scale] = #Hours, where Max Resolution = maximum digits and decimals for the Energy scale
in use.
Using the
example
from above, with an energy scale of Mega, the formula would be:
99999.999 M/86.4 M = 1157.4074 hours or about 48 days until rollover.
NOTE
:
To increase the number of days until rollover,
you can:
• Increase the number of digits (to 8)
• Decrease the number of decimal places (to 0)
• Increase the Energy Scale (to M).
Demand Averaging
Demand
is the average rate of energy use over time. The IQ 250/260 supports two types of demand averaging:
Fixed demand
and
Sliding demand
:
•
Fixed demand
records the average demand for time intervals that you define (usually
5
,
15
or
30
minutes).
•
Sliding demand
functions like multiple, overlapping Fixed demand. You define the subintervals at which an
average of demand is calculated.
An example
of Sliding demand would be a
15-minute Demand block
using
5-minute subintervals
, thus providing a new demand reading every 5 minutes, based on the last 15 minutes.
Summary of Contents for IQ 250
Page 2: ......
Page 22: ...3 6 IB02601006E www eaton com Chapter 3 Mechanical Installation IQ 250 260 Meter...
Page 38: ...4 16 IB2601006E www eaton com Chapter 4 Electrical Installation IQ 250 260 Meter...
Page 104: ...A 6 IB02601006E www eaton com Appendix A IQ 250 260 Navigation Maps IQ 250 260 Meter...
Page 134: ...A IQ 250 260 Meter Appendix B Modbus Mapping www eaton com IB02601006E MM 28...