Measuring The Average Active Power; Max Hold (Max Hold) - YOKOGAWA WT1800 User Manual

If an operand in an equation is undetermined, the computed result is displayed as "-------" (no data). This
occurs when a delta computation measurement function is in the equation, but delta computation is turned
OFF, or when a measurement function of an element that is not installed is in the equation.

Measuring the Average Active Power

The average active power can be computed for devices, such as intermittent control devices, whose power
fluctuates. Use a user-defined function to specify the equation for computing the average active power.
Average active power =
Use the equation above. For example, to determine the average active power of element 1, set the equation of a
user-defined function as follows:
WH(E1)/(TI(E1)/3600)
The unit of TI values is seconds.

MAX Hold (Max Hold)

Selecting Whether to Hold the Maximum Numeric Value (MAX value) You can determine the measurement
functions whose maximum values will be held using a user-defined function. The different types of operands are
listed below (measurement function: operand).
Urms: URMSMAX( )
Umn: UMEANMAX( )
Udc: UDCMAX( )
Urmn: URMEANMAX( )
Uac: UACMAX( )
U+pk: UPPEAKMAX( )
U–pk: UMPEAKMAX( )
To hold the maximum value of the Urms for element 1, enter URMSMAX(E1) in the equation for a user-defined
function, and enable MAX hold.
• For information about the parameters that you can use with each operand, see appendix 6 in the getting
started guide, IM WT1801-03EN.
• The maximum values of the data above are held while the MAX hold function is enabled.
• The D/A output values, the values in the data lists printed by the built-in printer, and the communication values
all reflect the held maximum values.
• When MAX hold is applied to measurement functions that have positive and negative values, the WT1800
compares the absolute values to determine the maximum value.
• To reset held maximum values, turn MAX hold off, and then turn it on again.
IM WT1801-01EN
Integrated power
Elapsed integration time
Irms: IRMSMAX( )
Imn: IMEANMAX( )
Idc: IDCMAX( )
Irmn: IRMEANMAX( )
Iac: IACMAX( )
I+pk: IPPEAKMAX( )
I–pk: IMPEAKMAX( )
P: PMAX( )
S: SMAX( )
Q: QMAX( )
–––
–––
P+pk: PPPEAKMAX( )
P–pk: PMPEAKMAX( )
8 Computation
8-5