WAGO 750-494 Series Manual

Contents

38 Function Description WAGO-I/O-SYSTEM 750750-494 3-Phase Power Measurement ModuleManualVersion 1.2.0LimitsThe I/O module also offers limit monitoring. Limits for undervoltage, overvoltageand overcurrent can be set for each phase (WAGO-I/O-CHECK or Register 36-38,parameters 23-31). Signaling is carried out in the process image (PI).Pos : 75 /Serie 750 ( WAGO-I/O-SYST EM)/F unktions beschr eibung/Funkti onsbesc hrei bung 750-0494 - Mes sfehl er und M essgenauig kei t @ 24\mod_1446714888787_21.doc x @ 194992 @ 2 @ 14.4 Measuring Errors and AccuracyThe measuring errors of the I/O module are specified in the table below. Thevalues already take into account the errors caused by the connection method(single-ended 0.1%) and the calibration tolerance (0.1%). They apply to the entiretemperature range of 0 to 55 °C and to frequencies of 45 to 65 Hz. Outside thisfrequency range, the error is max. 2%.Table 16: AC Measuring ErrorsAC Measuring Errors 750-494 and750-494/000-001750-494/025-000 and750-494/025-001Voltage <= 0.3 % of full-scalevalue<= 0.5 % of full-scalevalueCurrent <= 0.5 % of full-scalevalue<= 0.5 % of full-scalevalueActive power <= 0.5 % <= 0.5 %Phase angle +/- 0.3° +/- 0.3°Frequency 0.01 Hz 0.01 HzThe harmonics components are determined on the basis of a number of individualvalues measured within the current curve shapes for voltage and current.Calculation is performed to yield the components included in the actual basefrequency (45 to 65 Hz) and their integer harmonics. The accuracy of thecalculation results is typically within a range of around 1%."Leakage effect" with the harmonics analysis!Harmonics components in the actual curve shapes for measured voltages andcurrents with non-integer multiples of the base frequency can affect the accuracyof the calculation results for "neighboring harmonics" (so-called "leakage effect“).The measuring accuracy of the I/O module falls when an RMS voltage falls below45 V. This state is called ZC limit and is displayed via the "D" LED (SAG LED).The following conditions can also degrade the measuring accuracy of the I/Omodule:1. If only one or two phases of the three-phase supply network are connected,higher measuring errors can occur in the voltage measurement (+0.1%).2. In AC networks only:If all phases fall below the ZC limit, accurate measurement of phase angle,