Measuring Errors And Accuracy - WAGO -I/O-SYSTEM 750 Series Manual

WAGO-I/O-SYSTEM 750
750-495 3-Phase Power Measurement Module
Tamper Detect
The function 'Tamper Detect' may be used to detect a fault current caused by a
defect machine or equipment.
In general, the sum of the 3 actual phase currents Lx is equal to the neutral wire's
current in a faultless supply network. Therefore the I/O module calculates the sum
of the 3 actual currents Lx
and subtracts the actual neutral wire's current. The result is the fault current
If it is higher than the set threshold (WAGO-I/O-CHECK or Parameter 32/33),
signaling is carried out in the process image (PI).
Type of current transformer!
In order to achieve correct results all current transformers must be of the same
type!
Limits
The I/O module also offers limit monitoring. Limits (thresholds) for undervoltage,
overvoltage and 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).
4.4

Measuring Errors and Accuracy

The measuring errors of the I/O module are specified in the table below. The
values already take into account the errors caused by the differential connection
method (0.1%) and the calibration tolerance (0.1%). They apply to the entire
temperature range of 0 to 55 °C and to frequencies of 45 to 65 Hz. Outside this
frequency range, the error is max. 2%.
'Rogowski' coils generate a frequency depending signal which increases with the
frequency. This effect is corrected however by the 'Rogowski' variant 750-
495/000-002 for the coils RT500 and RT2000.
Manual
Version 1.0.0
i (t) = i (t) + i
SUM Lx L1
i (t) - i (t)
SUM Lx N
(t) + i (t)
L2 L3
Function Description 33