kitControl-SlidingWindowDemandCalc

This component is available in the Energy folder of the kitControl palette. It simulates a demand meter (see, About demand meters) and calculates the sliding window demand for 5, 15, and 30-minute demand intervals based on an accumulative pulse counter input. It also calculates the total kWh since last reset and the hourly and daily kWh values.The hourly and daily kWh values can then be logged using a standard history extension setup to execute on-trigger only. The SlidingWindowDemandCalc object fires the hourly and daily triggers to align the kWh data correctly to actual clock values. The pulse input into the object is assumed to be accumulative (not delta pulses) that roll over after reaching the 16 bit limit (65535).The SlidingWindowDemandCalc object can be configured to reset all the calculated accumulative values on a preset interval such as at “noon on the first Sunday, every month”.

For more information about demand meters, see About demand meters.

About demand meters

A demand meter measures peak demand using electromechanical components, and provides a pulsed contact output in proportion to the rate of electrical consumption over a interval such as 15 or 30 minutes. The utility meter will record the highest average interval rate (kW), which will be billed as the “Demand Charge.” At the end of the billing cycle, peak demand will be read and the demand will be rest to zero for the start of a new billing cycle. The total consumption (kWh) is also totalized by the meter to determine the “Usage Charge.”The SlidingWindowDemandCalc object can simulate the demand meter by calculating the average value over an interval. On a normal update frequency, the kW data from the oldest sample is replaced by the kW data from the most recent sample. This constant updating of the kW information every scan is called a “Sliding Window Demand Value.” The highest “Sliding Window” demand reading may be higher than the utility demand since the calculation updates average demand every 2 seconds and the utility meter may be resetting on a fixed or discrete 15 or 30 minute interval.

Setup of the SlidingWindowDemandCalc object involves the following properties:

Consumption Facets

This property allows you to set the facets for the consumption output property:
- units
  
  Select the desired units from the drop-down option list. Default units are energy and kilowatt hour (kW-hr).
- precision
  
  Type in an integer to set the precision level for your data (how many decimal places to display).
- min
  
  Type in a value for the smallest allowable value of the output property (default is -inf)
- max
  
  Type in a value for the largest allowable value of the output property (default is +inf)
Demand Facets

This property allows you to set the facets for the demand output property:
- units
  
  Select the desired units from the drop-down option list. Default units are power and kilowatts (kW)
- precision
  
  Type in an integer to set the precision level for your data (how many decimal places to display).
- min
  
  Type in a value for the smallest allowable value of the output property (default is -inf)
- max
  
  Type in a value for the largest allowable value of the output property (default is +inf)
Current Pulse Count

Displays data from a link to a pulse counter input object indicating the running total of pulses.
Time of Reset

Displays the date and time of the last reset.
Demand 5

Displays the demand (kW) for a five minute window.
Demand 15

Displays the demand (kW) for a fifteen minute window.
Demand 30

Displays the demand for a 30 minute period.
Kwh

Displays the running kWh (consumption) value since the last reset.
Kwh Hourly

Displays the running value since the last hourly reset.
Kwh Last Hour

Displays the kWh (consumption) value for the last hour.
Kwh Daily

Displays the kWh (consumption) value since the last daily reset.
Kwh Last Day

Displays the kWh (consumption) value for the last day.
Kwh Per Pulse

This field allows you to set the value per pulse. It is usually noted on the meter or provided by the power company. It is how much energy each pulse represents.
Enable Reset

A true value in this field allows recurring automatic resets to happen at a frequency based on the following properties.
Reset Day of Month

Allows you to set the day of month for recurring automatic reset (if enabled) to occur.
Reset Day of Week

Allows you to set the day of the week for recurring automatic reset (if enabled) to occur.
Reset Time

Allows you to set the time of day for recurring automatic reset (if enabled) to occur.
Meter Rollover

Specifies the maximum value the meter provides before it rolls over to zero (0). The default value is 65535, the data type is a long (up to a very large number, 9223372036854775807).

An example SlidingWindowDemandCalc property sheet is shown in Figure 47:

Figure 47. Example SlidingWindowDemandCalc property sheet