4-12
IM WT5000-01EN
The held null value is cleared under the following circumstances.
• Operations that cause the null values of all inputs to be cleared
• Turning on the power (the null values are not backed up when you turn off the power)
• Initializing the settings
• Loading a setup data file
• Operations that cause the null value of the input whose settings were changed to be cleared
• Switching between direct current input and external current sensor input
• Changing the Sense Type setting for the Speed or Torque motor evaluation input signal
Null Values
When you enable the null feature, the following measurement values are used as the null values.
• Udc and Idc (simple voltage and current averages)
• Speed, Torque, and Aux signals (on models with the motor evaluation option)
Measurement Functions Affected by the Null Feature
All measurement functions are affected by the null values.
• If there are no previously measured values for Udc, Idc, Speed, Torque, or Aux, because for example the
null feature has been turned on before any measurements have been made, the null values are set to
zero.
• For measurement functions that are computed based on an element’s voltage and current values, the null
values are subtracted from the sampled voltage and current values.
• For motor evaluation measurement functions and auxiliary input measurement functions, the null values
are subtracted from the computed numeric data.
Enabling and Disabling the Null Feature (Null, NULL)
• When you tap Null or press NULL, the null feature is enabled. The NULL key illuminates.
For items that null states are set (Target Element), Null indicators illuminate to the left of the elements, motors,
AUX inputs that are set to ON or Hold.
Null
Indicator
• If you tap Null or press NULL while the null feature is enabled, the NULL key light and Null indicators turn off,
and the null feature is disabled.
4 Input Settings (Advanced/Options)
