Specifications 39
Condition 1 - Normal Operation
Line voltage:
-20% to +15% of nominal
Power factor:
1.0
Frequency:
48 - 62 Hz
Ambient Temperature:
25°C
CT Current:
5% - 100% of rated current
Accuracy:
±0.5% of reading
Condition 2 - Low CT Current
All conditions the same as Condition 1 except:
CT Current:
1% - 5% of rated current
Accuracy:
±1.0% of reading
Condition 3 – Very Low CT Current
All conditions the same as Condition 1 except:
CT Current:
0.2% - 1% of rated current
Accuracy:
±3.0% of reading
Condition 4 - High CT Current
All conditions the same as Condition 1 except:
CT Current:
100% - 120% of rated current
Accuracy:
±1.0% of reading
Condition 5 - Low Power Factor
All conditions the same as Condition 1 except:
Power factor:
0.5 (±60 degree phase shift between current and voltage)
Additional Error:
±0.5% of reading
Condition 6 - Temperature Variation
All conditions the same as Condition 1 except:
Ambient Temperature:
-30°C to +55°C
Additional Error:
±0.75% of reading
Measurement
Creep Limit:
0.067% (1/1500th) of full-scale. Whenever the power or reactive power for a phase
drops below the creep limit, the power or reactive power for the phase will be forced to zero.
Also, if the line voltage for a phase drops below 20% of nominal Vac, the output power for the
phase will be set to zero. These limits prevent spurious readings due to measurement noise.
Update Rate:
5.0 seconds. Internally, all measurements are performed at this rate.
Current Transformer Phase Angle Correction:
1.0 degree leading. Current transformers (CTs)
typically have a leading phase angle error ranging from 0.2 degrees to 2.5 degrees. The
WattNode meter is normally programmed to correct for a 1.0 degree phase lead to provide
good accuracy with typical CTs.
Over-Voltage Limit:
125% of nominal Vac. Extended over-voltage operation can damage the
WattNode and void the warranty.
Over-Current Limit:
120% of rated current. Exceeding 120% of rated current will not harm the
WattNode meter but the current and power will not be measured accurately.
